Quick building strategies

[simon]

Hello everyone,

what are the options for building a catamaran and not spending valuable years of your life and lot of your financial ressources doing so. I like the Bob Oram's approach with building pre-cut kits with hard chines. Are there any other designers or approaches in the range of 40 - 50' with a focus on building a catamaran for a reasonable amount of money, in a short time?

The ones I know are:

- Schionning Design
- Fusion 40
- Spirited 380
- D. Dix
- Kurt Hughes
- Wharram

But even so, the projects that are present on the internet seem to take up years.

Does anyone have experience in successful projects that have been completed in a short time?

I have tried to reach Bob Oram, by Email, phone and web, but it seems that there is no way to get in touch with him. Does anyone have his email? Or does he avoid any contact?

Simon

[Freenacin]

It comes down to how much you can afford to pay. The Fusion is probably the fastest boat to build, but it's the most expensive kit to buy. The spirited would be next. ie. Cheaper but slower to build. (There is a similar type of kit to the spirited available from RMK marine too, for a similar price.)

Most of the Schionning designs are strip plank cedar - fairly inexpensive, but huge amounts of work. The flat panel Schionnings are quicker builds, but IMHO Schionning doesn't take full advantage of the building material - he basically builds his Duflex boats the same way as the strip cedar boats - upside - down around the bulkheads. This adds unneccessary difficulty IMHO - you have to use ratchet straps to lift and hold the panels in place, (some of these are very large and quite heavy) and you have to stand on raised platforms to work overhead inside the hulls, with epoxy dripping down on you, surrounded by epoxy fumes.

I feel that Bob Oram has the better building method for flat panel boats - right-side up inside female frames.

[waikikin]

Nice question Simon,I reckon anything thats contact molded with gelcoat finish is gunna be the quickest, anything that needs fairing-epoxy primer & poly-u shot at its gunna wear you down, kinda suck the energy out of you before you get to bolt down the beautiful shiny deck gear & do some nice joinery inside- these things still take plenty of time but they do on the faired & sanded boats too(when your worn out). plenty Knock molded & gelcoated vessels in the multi world(for weight & build quality) but often "have an agenda" - as I do too! Years ago my girlfrend(now wife) & I bought moldings of a Beach Marine(no longer trading) molded cat- probably agricultural compared to some other vessels but fitted with engine first made a great motor boat, later fitted with rig & sails made a fabulous cruising home & we sailed & enjoyed her very much sooner than "building from scratch". Many of the kits on offer seem to be not a lot more than a materials package with some "easy construct" spiel to go with it attached, sounds like your doing the research & aware of this, on your list I'd rate the Fusion & then the Spirited at the top for build speed but the fusion will be much less effort from the start & always worth real money to resell if circumstances change during construction, the spirited will be the quicker boat to sail but at a later date(although I dont know how long kit delivery affects this as they both may have some lead time). My next cat will be an Egan 12.40 thats molded & gelcoat finished, cant rate her for sailing or build speed yet but the pedigree is certainly there. All the best from Jeff.

[simon]

Looking at the possibilities that exist nowadays e.q all the Compute aided tools, I believe that there should be ways to design structures that are very simple to build, with a minimum number of elements to assemble ( hulls, bridgedeck and interior), but still are visibly appealing and performing well (of course a very personal matter). I agree with Bob Oram that length matters and would rather go for longer hulls with less living volume and structural weight. They will be more seakindly and accept more payload.


One problem with the leisure marine industry is the model launching cycles are very long and very few units are build (Compared to the car industry). To gain experience through feedback takes too long and the knowledge is kept by a few people who have been in the business for a long time.

I think the Spirited 380 is a refreshing approach by a younger architect.

Is there anyone out there who has experience in building a catamaran in the range of 40' - 50' in a few months.

Thinking of the old times when bigger wooden boats where built and launched in a few months. In some countries this is still the case. In the south of Chile, wooden fishing vessels (> 40') are ready to be used within 3 Months ( build by 2 people) and do not cost a fortune. Of course the finish is not the nicest, but what matters is being out there on the water. So what happened to efficiency by modern tools and methods?

Simon

[garydierking]

http://www.kelsall.com/

[catsketcher]

Hello Simon

You can build a boat in a few months. I was lucky enough to get on Thomas Covilles 105ft tri which was built in less than a year - but it still had over 30 000 man hours of work in it. You need lots of people.

I guess I will be the bad bloke and say it - you can't get a good big boat quickly. Bob's boats, any Schionning Jeff or Craig , or the Fusions will take time and awful amounts of it around 5-7000 hours for most. The Fusion will be less but is a little deceiving as to build times as it is a shell. If you include the time taken to build the interior then the time balloons.

You can build a shell in a few months. About 15 years ago a guy on the lake built a 38ft Grainger in 18 weeks so that he could motor it home. Then he took over ten years to finish it inside and out. Please don't think that you will be able to get around some concrete fundamentals - boats are big and composites take lots of time to construct.

Even with the kits a boat can take time - my mate I built my little folding cat next to took 5 years of full time - no weekends - to build an immaculate 1320 Waterline. It is gorgeous and he enjoyed the build.

I would encourage you to build something small - even kayaks can take a few months part time and fully understand why these things take time. It will help you become fully aware that building the hulls is only a fraction of the time required for building a boat.

My own preference is to get absolutely all of the boat computer cut. It is the interior of the boat that usually takes the greatest amount of time.

One of the best bits of boatbuilding advice was given to me by a friend. When I asked him about how much his boat had costed I looked quizzical - I has heard lower estimates of the same boat. He said

"Don't go around picking out what you want to hear. At least pick the average of the comments you get."

cheers

Phil Thompson

[Freenacin]

How long it will take really depends on the standard of finish you are willing to accept. But even so, most kits will take 3000 hours and upwards (for a very basic finish).

I met someone who Launched an Oram 40 (an older design) in one year. He had use of a shed for 12 months, and lived in it, and spent every waking hour working on his boat, but he did launch a quite well finished boat in 12 months.

The Fusions and RMK will be quicker, but you pay for that in $$$. Kits like the Spirited will save some time in interior fitout compared to say, the Oram, but you lose flexibility too. I know someone building a Spirited and he HAS to use saildrives, even though he would prefer outboards. Also, much of the Spirited 380 interior kit is made from Featherlight, which has a paper honeycomb core - I would not use this material by choice for any part of a boat.

[kengrome]

Is there anyone out there who has experience in building a catamaran in the range of 40' - 50' in a few months?It takes lots of guys working full time to do this, and the money to pay them consistently so they keep coming to work every day. It also helps if the materials are readily available, the design is simple, and the workers are experienced.

Thinking of the old times when bigger wooden boats where built and launched in a few months. In some countries this is still the case. In the south of Chile, wooden fishing vessels (> 40') are ready to be used within 3 Months ( build by 2 people) and do not cost a fortune. Of course the finish is not the nicest, but what matters is being out there on the water. So what happened to efficiency by modern tools and methods?When people care more about what a boat's finish looks like than how it performs it will always take a long time to satisfy them. At least where my shop is located they can afford the labor ... :)

[northerncat]

build a ply boat like the waller sunseeker or the snell easys, these can be and are put together in 6mths by 2 guys, yes they are ply but ive seen at least 2 where you wouldnt be able to pick it, my next boat might be an oram but my current one an easy has taken only 2 years to build part time by only myself and i work full time and have a family of three kids
sean

[rob denney]

G'day,

Google Scrumble and email Tom and Judy, they handle Bob's web page. They are also building one of his boats.

Build time is about surface area, finish and technique.

Bridge deck cats have huge surface area, much of which is not doing much, most of the time.

If you want a show room finish, it takes a lot longer than if you skip to the finish the boat will have after a season of knocks and bumps, fender scratches and dinghy bashing.

The quickest non moulded technique I have come across is KSS. Even quicker if you get a workshop happening for interested locals. We built two 50' half hulls and a deck in 4 days. Not very good gel finish, minimum weight vac bagged skins and core, very clean, quite cheap materials, little or no wastage and hardware store consumables. Plenty of critics, but very hard to find one who has actually seen it happen.

Regards,

Rob

[Spiv]

Having built a Schionning 12.5m I can tell you that the fairing is the most time consuming and colstly part of the building process.
Boats that have a lot of round surfaces are a real pain to build and slippery and unsafe later on in the water. You drop any thing and it ends up in the drink.
Stay away from pretty rounded decks and choose a design with more flat surfaces.
I agree with Rob about the KSS boats and Dereck Kelsall will help you do it properly.
Also look at the Easy, they are really easy to build and go well.
By the way, my Cosmos took 2y to build in a boat yard: two of us (partners) and a professional boat builder for 10 months solid, 6 days a week 10h/day, then 14 months the two of us with the occasional professional help in fairing and painting. We ended with a nice shiny charter boat, but it took twice what we expected and cost us nearly twice as much as what we were lead to believe it would cost.

[simon]

Thank you all for your replies.

I have never actually seen the KSS technique in action and there are a lot of critics out there about it.

I heard a lot of good things about Bob Oram.

Both designers have specialized on specific looks and also design philosophy what introduces an extra decision difficulty, besides the building technique.

I guess that building of the hull structure takes up big part of construction time. But interior fit out, technical installations and finally the finishing will weigh even heavier. So the hull building technique is just on part in the game of efficient boat building;


****
?What are your experiences about the time spent for the various building phases?


The lesson I learned from the complete interior refitting of my 36' monohull, is:

20% structure
30% detailing
10% technical installation
40% Sanding, fairing, sanding, fairing, painting, sanding fairing.....

My conclusion was, to use as many pre-sheeted elements as possible to minimize the finishing work. ( by the way, what about sheeting hard chined hull exteriors with some tough finishing panels, no painting needed?)

Also I believe that there is a lot to be learned and improved through something like gathering "best practices" for efficient and low cost boat building.

******
What are the experiences and opinions out there for something like "best practices" in efficient and low cost catamaran building?

- for building the structure
- fitting out the interior
- technical installations
- deck fit tout
- finishing

*******

All the best

Simon

[Fanie]

all the Compute aided tools, I believe that there should be ways to design structures that are very simple to build, with a minimum number of elements to assemble

Very possible, you can have the parts pre-cut from lightweight closed cell rigit foam and then fit them together like a puzzle. Couple of small problems though. You'll need a fairly large machine to do the milling and someone has to spend quite a bit of time on a computer to develop the software and to plan the parts, so economy flies out the hatch yet again.

[rob denney]

[QUOTE=simon;166327]Thank you all for your replies.

I have never actually seen the KSS technique in action and there are a lot of critics out there about it.

I do not know of any critics who have actually seen it in action. I have been an ardent strip planker for 20 odd years, been involved in maybe 1,000 of them. I changed my views after a KSS workshop. As did 3 other professional strip plankers.

I guess that building of the hull structure takes up big part of construction time. But interior fit out, technical installations and finally the finishing will weigh even heavier. So the hull building technique is just on part in the game of efficient boat building;

This is true, but it is possible to design a boat which has less surface area, lower loads and consequently is lighter, easier, quicker and cheaper to build. Harryproas are a good example of this. We have a 15m/50 footer sailing in Holland which is cedar strip, has huge accommodation, a covered cockpit for 6, sails at better than wind speed and weighs 2.5 tonnes, sailing. Most of the fit out is structural, most of the loads are concentrated in a very small area. A lighter boat. with less surface must be quicker to build. Add in a deck layout with no fittings except for a winch, a balanced rig with no wires, and 2 oversized rudders replacing the daggerboards and rudders on a cat, and you have much less work to do.

A video of the dutch boat is at http://www.zeilenmetvisie.nl/NL/onderZeilFlash.html

video of a heavy (3.5 ton) cruiser version effortlessly doing windspeed is at http://www.youtube.com/watch?v=8chR6DAFjGA

web page http://www.harryproa.com/visionarry.htm

Regards,

Rob
www.harryproa.com

[Bruce Woods]

Hi, I'm not sure theres such a thing as a quick build. Leaving things out, such as not fairing the structure, basic interior and keeping things simple will certainly speed the building up.

I'm not sure the 50 foot harryproa has many advantages in this regard after reading robs web site. The cruising version is listed as :

3 tons empty
1.7 tons payload
So sailing weight is 4.7 tons
2 queens and one single ( similar accomodation to 30 ft cat)
approx build time 4500 hrs
factory built "Rare Bird" 4750 hours
For sale for $180,000 Aus Brand new. ( wouldn't even cover build cost ex factory )

So if one is prepared to put up with the inconveiniences of a proa you get 20 feet of extra boat length . cheap and quick?????

Regards.

[rob denney]

Hi, I'm not sure theres such a thing as a quick build. Leaving things out, such as not fairing the structure, basic interior and keeping things simple will certainly speed the building up.

I'm not sure the 50 foot harryproa has many advantages in this regard after reading robs web site. The cruising version is listed as :

3 tons empty
1.7 tons payload
So sailing weight is 4.7 tons
2 queens and one single ( similar accomodation to 30 ft cat)
approx build time 4500 hrs
factory built "Rare Bird" 4750 hours
For sale for $180,000 Aus Brand new. ( wouldn't even cover build cost ex factory )

So if one is prepared to put up with the inconveiniences of a proa you get 20 feet of extra boat length . cheap and quick?????

Regards.

G'day,

Cheap and quick compared to any other boat of similar performance and space, yes. If you know of any videos of 30' cruising cats (or 40 or 50 footers for that matter) cruising at wind speed as effortlessly as Rare Bird, please let us know and we can compare prices.

They are not so cheap if you compare the number of bunks, but if we did the cat trick and filled every available space with bunks (2 more doubles in the lee hull), then they are cheap on this basis as well. Reality is, few people cruise with more than 5 people on board, unless they have boats which require extra crew to handle them. We prefer to build the whole boat round this number rather than try to con owners that 8 people can live and cruise on a 40 footer.

The only valid part of your comparison with a 30 footer is perhaps the building time, although the Visionarry did include 600 hours building the mast and boom, it was the first example of a totally new type of boat, so the next one will be quicker.

According to Schionning and Woods, most 30 foot cruisers have about 50% of the payload. None have the performance, sea keeping, safety or internal and external space.

Not sure where you got the price, but a new 50 footer to cruising stage is about $400,000. Rare Bird is for sale (the owner died after only sailing it twice), ready to cruise for $325,000. http://www.harryproa.com/brokerage.htm

Please tell us more about the "inconveniences" of a proa.

regards,

Rob

[Trevlyns]

I think Rob has a some very valid points. I don't think many people have seen the benefits of a larger cruising proa as there simply aren't so many around. I've looked at all manner of sailing craft in depth and am totally convinced that the proa - specifically the modified Pacific proa - is the most efficient and economical.

My wife and I are in our late 50's and I've just started work on a 12 meter proa of my own very basic, ply over frames design. She will be equipped with two double berths, ample saloon, head, galley and office space and a good safe deck area. I have just acquired all the material to complete the longer leeward hull for a little over £100 and expect to complete the boat for under £1000. Costs are of course relative. Just how much boat do you want? Granted, my hard chine flat bottom design is probably not as efficient or professionally finished as Rob's great designs; but my point is that it is totally adequate for our needs - that is a basic safe quick cruising boat built on a shoestring budget. Over the past two years, I've also gathered 90% of the equipment needed mostly through e-bay. Believe me, there are bargains to be had out there if you only look around!

[simon]

When starting this thread, I did not want to discuss specific design approaches ( proa versus rest ), but wanted to find out more about building strategies.

I would like to come back to ways to build our toys in a reasonable timeframe.

As Rob has been convinced by the KSS method, I would be interested in knowing ways to reduce the still huge amount of hours to build his proa design.
Rob, do you have any proposals or experience?


Are there any further methods that will simplify the construction?

Derek Kelsall writes in his website about radius batten to be used for bonding structures together. Any ideas about that?

What about using prepared standard profiles to bond in Bulkheads and assembling structures? Anyone knows about existing solutions?


Simon

[rob denney]

When starting this thread, I did not want to discuss specific design approaches ( proa versus rest ), but wanted to find out more about building strategies.

I would like to come back to ways to build our toys in a reasonable timeframe.

As Rob has been convinced by the KSS method, I would be interested in knowing ways to reduce the still huge amount of hours to build his proa design.
Rob, do you have any proposals or experience?


Are there any further methods that will simplify the construction?

Derek Kelsall writes in his website about radius batten to be used for bonding structures together. Any ideas about that?

What about using prepared standard profiles to bond in Bulkheads and assembling structures? Anyone knows about existing solutions?


Simon

G'day,

The easiest way to lower hours (and cost and weight) is to reduce surface area, concentrate the loads and minimise or eliminate fittings such as the stays on masts, deck gear, daggerboards and their cases. This is why the proa was mentioned. If you want to build a standard bridge deck cat with a good finish and fitout, there are very few cost effective shortcuts.

The "huge hours" are for a superbly finished strip planked boat and include the rig and a lot of messing about as it was a prototype. In KSS it would be quicker.

Derek's deck edge radius is a wonderful thing. It is built with the infusion and just needs abrading, some glue and a little bit of bog to complete the join.

Standard profiles are ok for long straight joins, but are hard to bend. Filletting and tabbing is pretty quick once you get into it. The main tricks are to pre wet the tape and apply it before the fillet starts to cure.

Computer cutting the foam for bulkheads will save a little time, but it is lost when you have to lay them up. Quicker to infuse big sheets and cut the frames from them, either with paper templates or on a cnc machine. Wastage with modern nesting programs is negligible.

After surface area and load concentration, the biggest saving is finish quality and interior fitout. My personal best is 450 hours for two strip planked hulls, beams and rudders http://www.harryproa.com/Newsletters/news1_hg1.htm and http://www.harryproa.com/harrigami/hgtimelist.htm for the time sheet. Pretty rough up close, but from 20' away, it looked as good as any other boat. It has since been sold and tarted up to look brand new. http://www.harryproa.com/harry_proa/NZ/2.htm

regards,

Rob

[catsketcher]

Simon,

The idea of reducing building hours has been with us ever since multis have been built. Probably the best boats to build are old tris - the guy who designed the Easys - Peter Snell - built a 38ft Piver tri in about 6 months. The Piver AA38 makes a good boat and really is pretty simple to build.

There have always been new techniques - quick strip cedar, strip plank itself, vertical strip foam, chined plywood, turbo plank - it has always been thus. KSS is a new technique and like its predecessors will have its advantages and problems. ( No I haven't gone to a workshop but I have friend who did run a KSS workshop at his house. He is not overly enamoured with the technique and we have discussed it a fair bit.)

Hulls take little time to build compared to the interior and fit out. This is why I do not necessarily agree with techniques that compromise the ability to use computer cut components. You will be able to knock up a couple of 12 metre cat hulls in 3 months roughly faired - no kidding. But these hulls could be used in a 12 metre cat could take 3 years full time to complete.

Bunks, cupboards, sinks, lights, floors, bulkheads, fridges, seats, benches, basically anything you want inside a boat will take lots of time to fit - because you have to be careful to build a good boat.

If you want to live in a shell or get rid of the volume and stuff in an interior then you will take less time. Getting a slick boat with a nice interior will take lots of time. There will not be a magic idea to get around the thousands of hours to build a boat.

cheers

Phil Thompson

[waikikin]

Simon, maybe you can incorperate some of the facets of melamine molding to the Oram cat? say like instead of premanufactered panels that need joining on site make a nice big laminating table & mold the full length hull & deck panels to shape with gelcoat & also incorperate some tabbing rebates to perimeter so you dont have to fair out the tabbing across a lot of the panel or use the edge radius to hull chine intersections as well. Like Rob has mentioned you can get pretty quick at tabbing especially if theres 2 on the job but there is plenty of it like 30 metres+ per connective bulkhead x 3 or 4 & often bulkhead edges have some uni glass to install too plus all the longtitudinal joins as well as furniture & tankage thats part of the structure. As has been mentioned fitout style & finish has a great influence on build time & is purely your choice, the super "tight" joinery & 16 coats of clear is gunna suck up heaps of hours, the stippled flowcoat & frontrunner or other monkey fur fabric & some satin finished trims & fiddles backscrewed & stopped short of the bench ends for wipeouts are gunna be quicker overall but will still take time but still look nice if neatly executed. Phils no "magic" idea line is correct on the 1000's of hours but there are still margins to be chased but can impact on finish & eventual resale values(they all get sold one day & I'd say Wharrams suffer the most here), the "panel"(duflex?) style boats seem to at least in Oz have acceptance but I dont know elsewhere how they go. Personally I've invested in some pretty sweet production quality tooling for my hull construction but intend to build a few to spread the cost of over but I 'spose thats my own choice. All the best from Jeff

[Bruce Woods]

Hi,
I'm not as familiar with the KSS method as with stressed ply, but one would have to assume that bending a flat pannel of foam and glass into compound curves and then cutting bending and glassing gussets is not an exact science.

Therefore the final hull shape depends on many unknowns relating to pannel stiffness ( state of cure, resin/glass ratio etc etc), and builders eye. There would be little point in computer cutting the interior if it aint going to fit. If this is the case some of the time gained in a quick Build hull skin is lost.

This system probably still has some advantages if your happy with a hull without topside curvature, flared bows, trying to match gelcoat finish on joins etc etc etc. Being infused ,with its inherent print through problems the finish is never going to be as good as a polyurethane paint finish.

regards

[fhrussell]

Maybe the time saving ideas should be concentrated on the interior. Having built many boats, I always find that so much much of the 'sense of accomplishment' comes from turning a completed hull, but that seems to be only one fifth of the way into the whole project. I believe that the cost of the hull construction is also about one fifth the total project. If this is so, then the time saving tactics are likely found on the interior and outfitting the decks.
Perhaps we should be talking about interior shortcuts instead of hull construction techniques...of course, not discounting the possible time saving ways to build the hull...ie; KSS, tortured-ply, etc.

My .02

[Fanie]

I think what may cause the concern is the sheer size of a hull that has to be glass covered.

[DGreenwood]

Perhaps we should be talking about interior shortcuts instead of hull construction techniques...of course, not discounting the possible time saving ways to build the hull...ie; KSS, tortured-ply, etc.

My .02

Exactly! A 40' boat with a 30' interior is really not very much harder to build than a 30 ' boat...but it sure is a lot nicer at sea. Give me 10 more feet of water line length over a second head any day.

[rob denney]

Hi,
I'm not as familiar with the KSS method as with stressed ply, but one would have to assume that bending a flat pannel of foam and glass into compound curves and then cutting bending and glassing gussets is not an exact science.

Therefore the final hull shape depends on many unknowns relating to pannel stiffness ( state of cure, resin/glass ratio etc etc), and builders eye. There would be little point in computer cutting the interior if it aint going to fit. If this is the case some of the time gained in a quick Build hull skin is lost.

This system probably still has some advantages if your happy with a hull without topside curvature, flared bows, trying to match gelcoat finish on joins etc etc etc. Being infused ,with its inherent print through problems the finish is never going to be as good as a polyurethane paint finish.

regards

G'day,

Your first 8 words sum it up pretty well.

KSS is exact enough for Derek to provide computer generated shapes for the interior, which fit. My windward hull has cantileverd bunks off one side. These, the cabin sides, deck and hull sides were all done from drawings, many with deck radiuses for joining. It all fits together very well.

The state of cure is near enough complete before bending is done, the table infused resin/fibre ratio is consistent and low, certainly far better than hand layup. There is very little eye balling required, much less than setting up a strongback for strip. There are far fewer variables, and much more complex shapes are possible than with tortured ply. One of our clients built a half hull mould and infused a 20m/66' hull and decks. It was far more complex, stressful and prone to errors than the table infusion Derek uses.

Topside curvature can be done (with the new foam compounding technique, a lot of mono hull shapes become possible), as can flared bows.

You are correct about gel coat matching at joins, although as the only one is the hull deck join, it is far easier than fairing and painting the entire hull. A strip can be painted on, non slip can be used, or you can spend a couple of days buffing and polishing gel coat. There won't be any print through if normal vacuuming into mould processes are used (tissue between the laminate and gel, maybe a light layer of csm before the bulk of the laminate goes down). The main problem is getting a perfect table for the gel coat to go on. On my boat, I didn't worry as the finish is immaterial, but if you want a shiny finish, then use sanding gel, and 2 part pu once it is all in one piece.

KSS and table infusion is not the absolute answer (still needs some hand laminating below the waterline), and paying Derek to alter plans is expensive, but it is faster and less messy than anything else currently in use. You and any other doubters should attend a workshop, or at least have a look at some of the pictures and videos on Derek's web site. There are some of a workshop in Toowoomba, where they made a flawless table. The finish on the (curvy) gel coated hull is as good as any you will see anywhere

Fanie, Table infusion takes all the concern away. You set everything up dry, taking as long as you like to ensure all is well. Then mix a bucket of resin, open the tap, have a cup of tea, close the tap and come back the next day and 90% (100% on the deck) of the laminating is complete.

D Greenwood, I could not agree more. And if only one hull needs to be lengthened, it is even cheaper.

Phil, I would be very interested to hear what you and your friend did not like about KSS.
It is not the building of the hulls or the interior that is the problem for most builders, it is the fairing and finishing.
A couple of unfaired strip planked 12m hulls in 3 months (with another 3 months of fairing to go) is pretty good, until you compare it with a couple of 12m hulls and decks, faired and ready for top coat in one month with KSS.

regards,

Rob

[waikikin]

Personally I reckon gelcoat is a fabulous material, matching a hull/deck/transom join with new material probably from the same batch is as good as it gets in that regard- it gets a bit tougher once the boats copped some uv for a few years with different tones apparent on various surfaces but its ussually possible to get close, I've blocked & buffed 20 year old boats that ended up presenting quite nice but of coarse some dont & need a shot of pu. Also I see no reason why there would be too many fit up issues on furniture etc to a kss hull, many years ago I built a Van De Stadt 34 that was computer modeled to give plate developments & all the Knockers & rudder kickers & gunnel leaners said theres no way that'l fold up right but surely enough it did just like stitch & glue style, why not now that the tools of computer modeling & Dereks experience in the technique can work up a nice hull, people have been doing triangulation & working girths to develop hulls for a long time, sounds like he's got a good technique & the talent & experience to back it. The Toowoomba workshop I would liked to have attended, I reckon I could use the table infusion myself for a lot of stuff, I really like the thought of sipping my tea while the job infuses with less stink & slushie action, I think I might order a couple of sheets of infusion foam & resin & have a play around with it. Rob, sounds like the new boats progressing nicely. Regards from Jeff.

[doug kay]

I built my Cat in cedar strip and the hulls of a 12 metre would take,including the hardback, about 300 hours, mine is only 9 metre but the two hulls were built but not finished, ie still in their rough stage in 200 hours. Two people working 10 hours a day will have a basic boat in 9 months.

[northerncat]

i would agree with spiv stay away from boats with large compound curves if you are after speed of build and dont want to lose things over the side, go for a flat panel design for ease of fairing, as for hull construction my ply easy easy hulls were built over 10 weeks part time and this included glassed and fully faired id have to say this was the quickest aspect of the build

[catsketcher]

I really like the idea of having the curved part of the hull very accurate so that the computer cut interior can be easily installed. I also like having the hulls sit right way up and installing the interior before the skin goes on. This is how my little folding cat is built. It allows you to use the mould frames to give accurate elevations and spacings and makes the interior fit out much faster.

If I was to build another big cat I may like to consider a similar approach with some premade pieces like the KSS system. Making the rounded hull bottom (up to 50mm above waterline only) in strip foam would take little time - about 2 weeks on your own for a 38 footer (the little 7m folder takes 1 day to strip foam - 2 days to set up mould). It would then be glassed and the interior installed, then the infused flat topsides and decks installed. The hull bottom would need very little fairing as it would be underwater and painted with antifoul. As the rounded bottom (up to waterline) is symmetrical you would not need to reverse the hull mould and be able to make both hulls out of an identical mould.

This would give you an accurate hull and with glass table infused topsides and decks giving reduced fairing. Strip foam is really fast for curved bits and gives lots of control over the hull shape. It is also nice and sequential with no times when you might stuff everything up - you can also do it all on your own. This approach is similar to the Spirited 380 which I have seen quite a bit of. The ability to remove the topsides to work on the interior saves many tens of hours during fit out.

I already have three boats so will not be trying this approach on a 38 footer soon. I just put it out there for comment and consideration.

cheers

Phil Thompson

[simon]

Hello everyone,

thanks for the many interesting replies. I guess, as usual, there many paths that lead to the goal and there are many choices to be made.

Lots of the posts mention flatpanels for the ease of fairing and infusion is in the favor of many.

The idea of having a round bottom constructed separatedly seems interesting, as taping up several board to form the bottom, probably consumes also time and the difference will not be huge.
Producing flat topsides, decks, superstructure, (with infusion?) will cut down time.

What would be the options in technical installations like engines, rudders, daggerboards/keels, rigging and deckgear, to keep it simple, reasonably cheap and efficient for building?

I would be interested to hear from people that have finished the project in a short time and also hear about their choices.

A nice day to everyone

Simon

[doug kay]

I like the strip cedar constuction for the hulls, it's easy and it's quick. Building the hardback took about 30 hours for my 30 footer. Laying up the strips needs some preperation to avoid a lot of sanding later by designing some method of alighning the strips along their length, they tend to spring. I simply cut the heads off copper nails but some builders use round and cove others tongue and groove but try different methods before you procede. You should have a hull in the rough after 20 hours or so. You then apply glass cloth, I used bi-axial and epoxy resin which resulted in an enormously strong hull.

[rob denney]

I really like the idea of having the curved part of the hull very accurate so that the computer cut interior can be easily installed. I also like having the hulls sit right way up and installing the interior before the skin goes on. This is how my little folding cat is built. It allows you to use the mould frames to give accurate elevations and spacings and makes the interior fit out much faster.

If I was to build another big cat I may like to consider a similar approach with some premade pieces like the KSS system. Making the rounded hull bottom (up to 50mm above waterline only) in strip foam would take little time - about 2 weeks on your own for a 38 footer (the little 7m folder takes 1 day to strip foam - 2 days to set up mould). It would then be glassed and the interior installed, then the infused flat topsides and decks installed. The hull bottom would need very little fairing as it would be underwater and painted with antifoul. As the rounded bottom (up to waterline) is symmetrical you would not need to reverse the hull mould and be able to make both hulls out of an identical mould.

This would give you an accurate hull and with glass table infused topsides and decks giving reduced fairing. Strip foam is really fast for curved bits and gives lots of control over the hull shape. It is also nice and sequential with no times when you might stuff everything up - you can also do it all on your own. This approach is similar to the Spirited 380 which I have seen quite a bit of. The ability to remove the topsides to work on the interior saves many tens of hours during fit out.

I already have three boats so will not be trying this approach on a 38 footer soon. I just put it out there for comment and consideration.

cheers

Phil Thompson

G'day,

With KSS at least some of the shape of the topsides comes from the bending of the area below the topsides. You would get less shape in your topsides if you table infused them seperately. You are also making extra work, for no real gain as the interior of the KSS hull is very accurate above and below the waterline.

You did not tell us what your friend disliked about KSS?

regards,

Rob

[catsketcher]

The bloke who ran the workshop here had to spend a long time time fairing the boat after the workshop finished and the hulls were not exactly identical. I started my first folding cat about the same time as him. I have been sailing two and half years and he is still long way off. This has far less to do with KSS than with the time he spends on the boat. Having said that KSS won't make your boat happen overnight. You still have to put in hundreds or thousands of hours.

The infusion runs very well. I have seen hours of video of the process and my friend swears by it - it looks good.

I think Rob and I will have to agree to disagree over this one. I build cruising cats which have lots of interior even on the simple ones. I like to reduce the build time by leaving sides off and fitting interiors on a minimal shell bottom. It is also what Craig Schionning does on the Spirited 380. This build time will be the major part of the project so reducing interior time is important. Getting a hull done quickly is not going to get you sailing sooner if that method makes fitting the interior longer. Go and have a look at the method Craig and I used for our cats and see how easy it is to fit a floor when you don't have to stand on it and how quick it is to fit furniture when you stand on the shed floor and not in the boat. If a quicker interior method can be coupled with large panel infusion then I think that is a good road to proceed down. I am sure that large infused panels can have slight camber built into them by making the table slightly curved. This approach is old - Constant Camber and Varicam are methods that tried this before and it worked - they didn't use composites like foam and also tried to incorporate the rounded hull bottom into the mould. This forced the designs into certain constraints.

Rob's boats are minimalist and a world away from the cats I build. They (at least the leeward hull) are mostly hull and as such a timely hull building method will work wonders.

The proof will obviously be in the pudding. The only KSS boat I know is still two hulls years after starting. The Space 55 that was the first KSS boat in Australia was not in the water quickly either. All new theories have to be proven before they are accepted by the majority. When a 12m KSS boat gets sailing in less than 2000 hours with a good interior people will take notice and change their ways. Until then there will have to be conjecture and good mannered banter.

cheers all

Phil Thompson

[rwatson]

For what its worth, the KSS method has been constantly on the improve over the years.
Rob Denneys Proa is not a KSS design, he is just adopting the KSS methodology, because he has *done* strip planking in a big way and has nothing to prove his credentials as knowing the better way.
I agree that aspects of the KSS method some years ago had some critics - though none of their comments would have stopped me.
The new methodology is even better, and I am keen to use aspects of it for my next boat (not a cat)
I have never come across a faster method for a quality result than KSS - bar none.
Being close to completing a strip plank smaller boat, my experience is if you want the nice wood effect good luck to you - its a bugger of a way to do boatbuilding. For my money, a self build sailboat has to be either ply, or prelaid panels (like the KSS) or you are a masochist. You might talk me into steel for a big project too.
In any event, all the best for whatever you do - it can be fun.

[Fanie]

Fanie, Table infusion takes all the concern away. You set everything up dry, taking as long as you like to ensure all is well. Then mix a bucket of resin, open the tap, have a cup of tea, close the tap and come back the next day and 90% (100% on the deck) of the laminating is complete.

Hi Rob, I am aware of how the process works, and yes, it is easier than to run around with rollers and buckets of resin. It is not so easy however, if an area gets an air pocket enclosed in resin, ie the resin flows around it instead of through it, you would have to rework that dry area. Any way around this ?

I have also seen a cheap rope 'net' made around the subject to be resinned to better flow. Getting the plastic to seal all round can be difficult sometimes.

I have vacuum pumps I can use. If one can know where the problem areas are going to be it would be easier.

[yipster]

http://www.kelsall.com/methods.html

[rob denney]

For what its worth, the KSS method has been constantly on the improve over the years.
Rob Denneys Proa is not a KSS design, he is just adopting the KSS methodology, because he has *done* strip planking in a big way and has nothing to prove his credentials as knowing the better way.
I agree that aspects of the KSS method some years ago had some critics - though none of their comments would have stopped me.
The new methodology is even better, and I am keen to use aspects of it for my next boat (not a cat)
I have never come across a faster method for a quality result than KSS - bar none.
Being close to completing a strip plank smaller boat, my experience is if you want the nice wood effect good luck to you - its a bugger of a way to do boatbuilding. For my money, a self build sailboat has to be either ply, or prelaid panels (like the KSS) or you are a masochist. You might talk me into steel for a big project too.
In any event, all the best for whatever you do - it can be fun.

G'day,

Yes and no to the KSS proa. Derek reckons he can do pretty much any hull shape, (including monos) but then made a good case to use the shapes he had used in the past (slight V, slight rocker, flat decks). I figured it was worth a try, so went with his shapes. Whether they work or not, time will tell. Having seen the system, there is no doubt that our standard hull shape (semi circular sections, no rocker) could very easily be produced using KSS, in one piece, with very few, probably zero cuts.

The rest of your post is spot on. The knockers have never seen it in action, so can't/won't believe it. Derek's latest trick with torturing the foam takes the system to a new level.

regards,

rob

[rob denney]

Hi Rob, I am aware of how the process works, and yes, it is easier than to run around with rollers and buckets of resin. It is not so easy however, if an area gets an air pocket enclosed in resin, ie the resin flows around it instead of through it, you would have to rework that dry area. Any way around this ?

I have also seen a cheap rope 'net' made around the subject to be resinned to better flow. Getting the plastic to seal all round can be difficult sometimes.

I have vacuum pumps I can use. If one can know where the problem areas are going to be it would be easier.

G'day,

This was one of the highights of the workshop. There was an area where there was an air leak (hole in the plastic) near the edge, so the resin was not being sucked. Derek took a vacuum line, cut a hole in the bag and shoved the line in. It wet out immediately. Remove the hose, tape over the hole and the job is done. He also reckons he has never had a failure wetting out and bagging dry spots post infusion. Guess it is debatable whether this is more or less strong than cutting out the dry bits and patching them. Was not an issue on any of 4 hull sides, 2 decks and a pile of smaller parts.

The wet out is pretty uniform across the job, and air pockets are unlikely. This is not the case with in mould infusion, particularly with segmented core on tight curves. It is also very easy to follow the wet out and ensure it is complete. After your first test piece, you will be an expert. After your first hull, you will be ready to write a book on the subject.

Sealing the perimeter is easy as it is all on a flat shiny table, with no resin, unlike conventional vac bagging, which can be a nightmare. We used brown packaging tape and masking tape for most of it, vac tape for the rest. It is important that the bag has plenty of slack, but this is much easier on the flat than on a mould, particularly a female one. And there is no rush, unlike conventional vac bagging.

We used scored perforated foam on the lee hull. Worked well, but is expensive and the scores were too big so we have a bit of extra resin. On the ww hull, we used cheap shade cloth and perforated foam. Worked superbly.

Definitely easier. Also cheaper, lighter, quicker, more uniform, cleaner and there is no contact with smelly resin.

regards,

Rob

[Bruce Woods]

So most seem to agree that the hull skin is only a very small portion of a completed cruising multihull. Yes I understand Rob has a vested interest in pushing the KSS system so only highlights the positives and sells the possibles as do-ables. After reading the Mark Giles article on the recent Australian KSS workshop one is left wondering what the system advantages actually are. Quote .... Derek (kelsall) confirmed that a good paint system is essential for a lasting and attractive job. unquote. (topside print through and kerfmarks require fairing out)

Rob quoted in a post as saying the system adds substantial cost through licence payments and design mods to Dereck.

So one gets a limited hull shape at extra cost that still needs fairing and painting.

Having a commercial back ground in infusion moulding I must question the advantages for the first time back yard builder(you get to stuff up a lot of expensive materials quickly if things dont go quite right like a power failure during infusion for instance). Even using this technique you are still going to get covered in the sticky smelly stuff, Gelcoating, surface tissue application to try and stop print through , glassing the darts, hopping in the hull to glass the keel join , bulkheads, furnature etc etc etc...... And then theres the pile of consumables that end up in the trash can ( read money)

Regards

[rob denney]

Phil
The bloke who ran the workshop here had to spend a long time time fairing the boat after the workshop finished and the hulls were not exactly identical. I started my first folding cat about the same time as him. I have been sailing two and half years and he is still long way off. This has far less to do with KSS than with the time he spends on the boat. Having said that KSS won't make your boat happen overnight. You still have to put in hundreds or thousands of hours.

Rob
You denigrate the system, then blame the builder. Nobody said KSS would give you a boat overnight, just many months less than any other method.

P
I think Rob and I will have to agree to disagree over this one. I build cruising cats which have lots of interior even on the simple ones.

R
Sorry, this is a contradiction. Simple boats don't have lots of interior.

P I like to reduce the build time by leaving sides off and fitting interiors on a minimal shell bottom. It is also what Craig Schionning does on the Spirited 380. This build time will be the major part of the project so reducing interior time is important. Getting a hull done quickly is not going to get you sailing sooner if that method makes fitting the interior longer. Go and have a look at the method Craig and I used for our cats and see how easy it is to fit a floor when you don't have to stand on it and how quick it is to fit furniture when you stand on the shed floor and not in the boat.

R I may be wrong, but i can't see the time saved in installing the floor making up for the time spent planking, glassing and fairing the bottom of the hull, then attaching the topsides. And fitting the interior to the floor means you then have to fit and bond the hull sides to all the edges, and cut away the interior to bond the topsides to the bottom. Apart from the floor, this cannot be as quick as dropping the precut, prefinished pieces into the complete hull, filletting them in place, then gluing on the deck using a premade deck edge radius. No idea how Craig does it, but any labour savings don't seem to be reflected in the selling price.

P If a quicker interior method can be coupled with large panel infusion then I think that is a good road to proceed down. I am sure that large infused panels can have slight camber built into them by making the table slightly curved.

R Sure, you can build a curved table (with difficulty), and you can strip below the waterline, then join the two together. But why bother, when KSS does it all in one hit, in much less than half the time, with much less than half the hassle.

P This approach is old - Constant Camber and Varicam are methods that tried this before and it worked - they didn't use composites like foam and also tried to incorporate the rounded hull bottom into the mould. This forced the designs into certain constraints.

R Derek reckons, and I agree, that there are no cat hull shapes (and not many mono ones) that KSS cannot produce.

P Rob's boats are minimalist and a world away from the cats I build. They (at least the leeward hull) are mostly hull and as such a timely hull building method will work wonders.

R My boat is minimalist. The rest of the harryproa range are comfortably fitted out cruisers, designed to be easily built, so much of the fitting out is structural, and modular. This also keeps the weight down.

P The proof will obviously be in the pudding. The only KSS boat I know is still two hulls years after starting. The Space 55 that was the first KSS boat in Australia was not in the water quickly either. All new theories have to be proven before they are accepted by the majority. When a 12m KSS boat gets sailing in less than 2000 hours with a good interior people will take notice and change their ways. Until then there will have to be conjecture and good mannered banter.

R Phil, you are a bright guy, with a very clever boat, and I don't want to get into a pissing contest with you, but you are kidding yourself on the KSS vs other methods argument. You have blamed your mate for his boat taking so long, and the Space 55 was built by a bunch of Gold Coast clowns 10+ years ago. KSS has improved a lot since then. It ain't conjecture. Do yourself a favour and give it a go.

regards,

Rob

cheers all

Phil Thompson[/QUOTE]

[rob denney]

So most seem to agree that the hull skin is only a very small portion of a completed cruising multihull. Yes I understand Rob has a vested interest in pushing the KSS system so only highlights the positives and sells the possibles as do-ables. After reading the Mark Giles article on the recent Australian KSS workshop one is left wondering what the system advantages actually are. Quote .... Derek (kelsall) confirmed that a good paint system is essential for a lasting and attractive job. unquote. (topside print through and kerfmarks require fairing out)

Rob quoted in a post as saying the system adds substantial cost through licence payments and design mods to Dereck.

So one gets a limited hull shape at extra cost that still needs fairing and painting.

Having a commercial back ground in infusion moulding I must question the advantages for the first time back yard builder(you get to stuff up a lot of expensive materials quickly if things dont go quite right like a power failure during infusion for instance). Even using this technique you are still going to get covered in the sticky smelly stuff, Gelcoating, surface tissue application to try and stop print through , glassing the darts, hopping in the hull to glass the keel join , bulkheads, furnature etc etc etc...... And then theres the pile of consumables that end up in the trash can ( read money)

Regards

1) Try telling anyone who has glassed, filled and faired 2 cruising cat hulls, decks, cabin top and bridge deck (all of which can be built with KSS) inside and out that it is "a very small portion of a completed cruising multihull".
2) I have no vested interest in KSS. Or any reason to push it apart from trying to make life easier for other builders. The license fee goes direct to Derek. All our plans are for strip plank timber. I strongly resent your insult and ask that you retract it.
3) A gel coat finish seems fine for 95% of the boats in the world, but a quality paint job will give a better finish. Check out the gel coated Toowoomba boat mentioned earlier.
4) Hull shapes are not (for the nth time) limited.
5) The cost of the licence is higher than I would like, but is more than offset by the labour, mess and cost savings. If you are that much of a penny pincher, run a workshop and get Derek and a bunch of others to pay to help you build the boat.
6) There is a huge difference between flat table infusing and in mould infusing. Anyone who wastes materials with KSS is not following the very simple instructions.
7) Power cuts will muck up infusion. This is definitely a reason for spending 6 months of your life filling and fairing unnecessarily. If you are this paranoid, buy or hire a genset.
8) Read Mark's article. Nine of us went to dinner at the flashest restaurant in town after 3 days of infusing, in our work clothes.
9) Yes, there is some additional glassing and fairing to do and yes you will have to glass in your furniture, although what this has to do with building the hulls is beyond me. I never said KSS was perfect, just a hell of a lot better than anything else.
10) If you can't see the advantages, buy yourself a dust mask and a Tyvek suit and get started strip planking your boat. Makes no difference to me.

Regards,

Rob

[catsketcher]

The last thing this discussion needs is a long running argument developing. I am going to agree to disagree with Rob in this one and wish him well in his endeavours.

Diversity is a great thing.

Cheers

Phil Thompson

[rapscallion]

I like the idea of using the KSS method with Nidacore; or using a version of cylinder molding with nidacore and resin infusion. Nida is great stuff, and dirt cheap. Sherman Williams has some great marine epoxy that is much cheaper than WEST, and the stuff looks pretty good to me.

[Bruce Woods]

Hi,

Rob states " This is definitely a reason for spending 6 months of your life filling and fairing unnecessarily".

For a couple of cat hulls?

Come on Rob quit the exagerations , It certainly doesn't help. Then again ,after seeing the fairing on a couple of your creations I suspect you simply have no idea regarding fairing so we'll let that one through to the keeper .

Regards.

[rapscallion]

Hi,

Rob states " This is definitely a reason for spending 6 months of your life filling and fairing unnecessarily".

For a couple of cat hulls?

Come on Rob quit the exagerations , It certainly doesn't help. Then again ,after seeing the fairing on a couple of your creations I suspect you simply have no idea regarding fairing so we'll let that one through to the keeper .

Regards.


I bet you post on sailing anarchy... with a rapier wit like that you have to be careful.... you're liable to poke your eye out.

[waikikin]

Raps, dunno if thats rapier wit, just sounds like sh=t bagging to me, probably one of the most unhelpfull aspects of the Oz marine industry & all too easy to get dragged down by, the perpetrators let themselves down by their involvement, rather encouragement & support are much better & more valueable to all involved in my estimation. Regards from Jeff.

[Alan M.]

Most people will push the building method they are comfortable with. I haven't seen the KSS system at work so I can't comment on it, except to say that I wouldn't build using polyester or vinylester resin, which seems to have been the resin used in the recent KSS workshop. For such a small extra investment compared to the cost of the boat I would always choose epoxy.

I do have experience with building in Duflex, using Bob Oram's technique - right side up, in female frames. I can probably reel off fairly comparable hull build times to KSS.

In 8 days after starting from scratch, including setting up a strong back on a sloping dirt floor, and setting up the temporary frames, I had all the Duflex sheets pressed together, and a complete 44 foot bridgedeck catamaran hull along with half the bridgedeck floor built, ready for bulkheads to go in. If I had been pushing to get the hull turned ASAP, I could have done that one day later - after installing a couple of bulkheads.

Duflex requires relatively very little fairing - it naturally bends into very fair shapes, and all the fairing that is needed is to blend the tapes in.

You could have a pair of faired hulls, and a bridgedeck floor joined up, in probably less than six weeks if speed was your aim.

But for a fully fitted out 44 foot cat you are still going to be looking at probably 3000 hours as a minimum. If you want a decent standard of finish and fitout, then closer to 4000 hours for sure.

I would expect that even if KSS saved you some time building the hulls, your'e still going to be up for similar total hours for a similarly fitted out boat - I'm sure it is simpler to fit out a hard chined, flat keeled boat which requires no floors, compared to a round bilge boat.

[Fanie]

Most people will push the building method they are comfortable with
I feel the same as well. If one goes into production I would think the KSS would become much more attractive, and especially on large items.

[rwatson]

We are getting some heated comments here, and pride is always feature of professionals, and I learn a lot by the points raised. But I am a bit put off by the last bit of innuendo "no idea regarding fairing " - I would be much more interested in facts like - "the keel line showed wavy lines on xyz boat" or something concrete. Its a lot more usefull to understand a point of view if specific examples are shown or discussed. I have read one of Robs articles where he specifically spent less time on fairing to get a demonstration hull ready for testing by a certain date, so there is always background info to understand as well.
But back to the subject - quick building, I must admit as an interested observer (potential user of some method or other) the flat panel method makes the most sense so far, based on the hassles of getting any type of "goo" to to stay put on a non-horizantal surface. But the comments on getting the internals in place before putting a hull on impress me too. It makes just as much sense to finish and locate key bulkheads etc before the hull exterior - like the methods that use some of the frames as permanent component. Fiddling around in confined spaces, once again on non horizontal surfaces, sound like something to avoid, if possible.
I am interested in web sites that show a step by step applications of any type of methods for evaluation, but obviously people like to protect their good ideas. So I will keep on getting bits of advice here and there, sifting the discussions - and sifting the rhetoric and the facts.

[doug kay]

Could someone just explain what KSS is exactly, I've googled it but without success. I take it it is building with foam in one form or other. Thanks. I don't think it helps if writers opinions are simply dismissed or ridiculed, let's keep it friendly and we'll all learn something and you may encourage others to take up this wonderful hobby.

[doug kay]

Thank you for that excellent post rwatson. I have an idea which may be useful in cats. and a way to avoid the weather hull lifting and that is water ballast. Suppose a false bottom was built into each hull and filled with water it would weigh nothing under normal sailing conditions but should a hull try to fly then? Discuss please.

[rwatson]

Doug - the info on KSS was dropped in a few pages ago
http://www.kelsall.com/methods.html
compliments Yipster
The water ballast idea is perfectly viable, has been used on many production yachts already - but is probably going to be best dealt with in a new thread on that specific subject, - it certainly won't contribute to fast production of cats.

To take the fast building subject further, I found a site
www.scrumble.com.au
building a Bob Orram 44c, very comprehensive visual description of the techniques, replete with commentsa like "spent days re-fitting panels until it fitted etc"
It reminded me of just about every other building method I have read. Things are better though in that there is no overhead glassing involved , which was certainly a feature of at least earlier KSS techniques.

Both techniques have in common flat panel preparation and then assembly, though the KSS technique of moulding the foam in situ is a swish idea..

I am getting the feeling after considerable research that the fast boatbuilding technique may end up being function of the style and numbers of boats (multiuhull, mono, one off, production). For example - MacGregors would seem to have the asembly line technique down to a fine art, and he is very wary of soft panel foam cores. But for one off builders, doing plugs for GRP would be a waste of time, and maybe weight becomes a bigger issue for some boat designs than others.

Those people that commented on price being a function of ease of build have a great point. The proof would certainly be in the price - to coin a phrase.

[Alan M.]

Doug - the info on KSS was dropped in a few pages ago
http://www.kelsall.com/methods.html
compliments Yipster
The water ballast idea is perfectly viable, has been used on many production yachts already - but is probably going to be best dealt with in a new thread on that specific subject, - it certainly won't contribute to fast production of cats.

To take the fast building subject further, I found a site
www.scrumble.com.au
building a Bob Orram 44c, very comprehensive visual description of the techniques, replete with commentsa like "spent days re-fitting panels until it fitted etc"
It reminded me of just about every other building method I have read. Things are better though in that there is no overhead glassing involved , which was certainly a feature of at least earlier KSS techniques.

Both techniques have in common flat panel preparation and then assembly, though the KSS technique of moulding the foam in situ is a swish idea..

I am getting the feeling after considerable research that the fast boatbuilding technique may end up being function of the style and numbers of boats (multiuhull, mono, one off, production). For example - MacGregors would seem to have the asembly line technique down to a fine art, and he is very wary of soft panel foam cores. But for one off builders, doing plugs for GRP would be a waste of time, and maybe weight becomes a bigger issue for some boat designs than others.

Those people that commented on price being a function of ease of build have a great point. The proof would certainly be in the price - to coin a phrase.

One of Bob Oram's designs (that I know of) has provision for water ballast.
The "Mango" 38.

Regarding the "Scrumble" website - Tom is doing a superb job of his boat, but I don't think a super fast build is his main goal at this point in time, so it's probably unfair to judge how fast Bob Oram's construction method can be based on Scrumble.

I had no difficulty in fitting at least 2 bulkheads in a day - coved and taped on both sides. They don't need much trimming at all, in fact I learned from someone who is currently building his third 44C that if one of the pre-cut panels isn't fitting well, you have made a mistake somewhere.

Neil of Coolcats has got the build technique pretty much nailed down, and he gets his hulls together andfaired VERY quickly. Most of us doing a one-off like me, spend a lot of time thinking about our next step, and I have to say I do take some time to simply step back and enjoy the experience.

[doug kay]

Alan, I suspect it's a matter of whether you're building one boat or several. For production runs it pays to buy the equipment to cut down labour costs but for the backyard builder this isn't viable. I just can't understand why posters get so worked up about it, ya pays ya money and makes ya choice.

[rob denney]

G'day,

Bruce, My fairing cv includes the English 12 Metre Crusader ('87 Americas Cup), Ondine 4, (80' maxi), and more plugs, moulds and boats than I can remember. I have sold tons of bog to most of the gig Australian commercial builders and hundreds of cedar boat builders, then stood back and watched them turn most of it into dust. I was also involved in the development of the Powerboard, the only mechanical fairer I know of that actually does a reasonable job. I have far better things to do with my boat building time than waste it giving my boats a show room finish.

Raps and Jeff, Ta.

Alan M, A huge proportion of the boats in the world are built from polyester or vinylester. Used properly, they are excellent materials. Proper use is using a mould, and ideally infusing or at least vacuuming it. Secondary bonds and hand lay up, I agree, epoxy is best. Speed of cure is also a plus with the esters, you don't spend time waiting for things to cure. However, they stink, and styrene is not good for one's brain. Epoxy, on the other hand, is an allergenic, and once it gets to you, your building days are over.

8 days for a hull and half bridgedeck is impressive, you have my respect. I have seen Scrumble and they are doing a great job, but there is still a lot of fairing in of the tapes required if a show room finish is required. Chined boats are definitely easier to fit out (minimised if the fit out is computer drawn) , but don't perform as well as round ones. Probably not an issue for most cruisers.
rwatson, there are some pictures of the latest KSS build technique on the yahoo harryproa chat group photos section. You will need to join to see them. Any questions, please ask.

doug, few large cruising cats have hull flying problems, so water ballast is not required. If you do fit it, remember that everything has to be beefed up for the max load, resulting in a heavier boat, which will be slower when the ballast is not used.
regards,

Rob

regards,

Rob

[Fanie]

One of the time problems is always the time you take to get the glass wetted and applied quickly. Ideally you'd want to glass a whole structure out before any of the glass started to cure which makes the best structural bonds wether overlapped or layered.

I always had the idea that these old washing machines that uses two rubber rollers to dry the washing out or a similar machine should work perfect for wetting the glass out.

If the bottom roller sits in the mixed epoxy or polyester and the mat is rolled through it, it could wet the mat out as well as squeezing the excess resin back out very quickly.

The pressure of the top roller if adjusted could determine the amount of resin in the mat. The wetted mat can then be rolled up on a wide roller and rolled off on the item to be glassed.

Using a software like touchcad that can draw the mat in shapes that can be CNC pre-cut, it should only be a formality to quickly wet the mat and place it in position.

A CNC machine with a roller cutter (or maybe laser) could pre-cut the glass in the correct sequence and shapes faster than you could apply. Pre-cutting the mat and stacked in the right sequence would of course be better. Software nesting of the pieces would save material losses.

I would imagine one may be able to glass a complete boats structures in a single day this way, using only a small team of people. Ideally something like a hull would be easier to do if it can be turned.

One person keeps the mixed resin on level.

Two feed the mat strips or pieces into the rollers, and rolls it up on a roller as it is fed out, and then rolls the wetted glass onto the surface.

One person co-ordinates the placing of the wetted surfaces according to a worked out sequence and position schedule.

One or two or three people roll the air out of the applied material.

Using a second pair of guys they could also feed and roll the mat up while the first two guys are placing their mat.

[Alan M.]

G'day,


Alan M, A huge proportion of the boats in the world are built from polyester or vinylester. Used properly, they are excellent materials. Proper use is using a mould, and ideally infusing or at least vacuuming it. Secondary bonds and hand lay up, I agree, epoxy is best. Speed of cure is also a plus with the esters, you don't spend time waiting for things to cure. However, they stink, and styrene is not good for one's brain. Epoxy, on the other hand, is an allergenic, and once it gets to you, your building days are over.

8 days for a hull and half bridgedeck is impressive, you have my respect. I have seen Scrumble and they are doing a great job, but there is still a lot of fairing in of the tapes required if a show room finish is required. Chined boats are definitely easier to fit out (minimised if the fit out is computer drawn) , but don't perform as well as round ones. Probably not an issue for most cruisers.
regards,

Rob

regards,

Rob

Rob, the difference in wetted surface area between a multi-chine hull and a round hull is small. Balanced against the fact that to be habitable the round hull will need floors, adding significant extra weight, whereas a flat keeled multi-chine may not, (Orams up to and including the 44C don't have floors) the performance difference is probably too small to measure. It's even possible the floorless multi-chine may have an advantage. We raced a home-built, fully laden Oram 38 Mango against a resin-infused round bilged Fusion 40 (which had a vastly bigger rig, and much higher tech sails) at the recent multihull rendezvous, and absolutely thrashed it. In one race which took us 4 hours we beat them by over two hours. There are photo's and an article in this months multihull world - you can see the huge difference in rig size and sail area, as well as the carbon sails on the Fusion vs our dacron ones. A multichined boat won the division.

It's true there are thousands of poly and vinylester boats around the world. There are thousands of boats with osmosis too.

A friend of mine is building using infusion with epoxy - it's working very well for him. If I were going down the infusion path I would use epoxy too. In fact, the infusion technique would largely eliminate the main concern with epoxy - that of becoming intolerant to it, because of the minimal exposure.

There is also the consideration that the esters release styrene for several years - inside the boat, where you live - and as you say, it's not good for you.

Building your own boat is a major investment in time and money. I just wouldn't use esters - the savings are not worth it IMHO. But everyone has different priorities.

BTW getting one hull and half a bridgedeck together in 8 days wasn't any particular kind of feat - that's just how quickly it happens using Bob's kits.

Oh, and good luck in the solo transpac - I hope you do very well. Cheers, Alan.

[waikikin]

Fanie, what your describing is called a fabric impregnator, have a look at the pro set site, they got a nice 50" model on there, my dad made me one pretty similar & we intend to travel it over our jobs. Your a clever bloke, cause you've independently invented it too. Maybe in our case infusion might be a process that helps in the future too, which hopefully wont disapoint dad after the impregnator effort- should still be usefull on other stuff as well & he hates goo with a passion, & reckons epoxy will cross a room just to make him sticky! All the best from Jeff.

[Fanie]

Hi Jeff, what's the pro set site ?

Traveling it over a job is a good idea. I had the idea one could use a cart with hoist on a track kind of to get you into high places...

[waikikin]

Fanie, Pro Set is a brand for epoxy. Regards from Jeff.

[waikikin]

Fanie, if you google up proset epoxy & get to their site, look for process equipment & its in there. Regards from Jeff.

[rob denney]

One of the time problems is always the time you take to get the glass wetted and applied quickly. Ideally you'd want to glass a whole structure out before any of the glass started to cure which makes the best structural bonds wether overlapped or layered.

I always had the idea that these old washing machines that uses two rubber rollers to dry the washing out or a similar machine should work perfect for wetting the glass out.

If the bottom roller sits in the mixed epoxy or polyester and the mat is rolled through it, it could wet the mat out as well as squeezing the excess resin back out very quickly.

The pressure of the top roller if adjusted could determine the amount of resin in the mat. The wetted mat can then be rolled up on a wide roller and rolled off on the item to be glassed.

Using a software like touchcad that can draw the mat in shapes that can be CNC pre-cut, it should only be a formality to quickly wet the mat and place it in position.

A CNC machine with a roller cutter (or maybe laser) could pre-cut the glass in the correct sequence and shapes faster than you could apply. Pre-cutting the mat and stacked in the right sequence would of course be better. Software nesting of the pieces would save material losses.

I would imagine one may be able to glass a complete boats structures in a single day this way, using only a small team of people. Ideally something like a hull would be easier to do if it can be turned.

One person keeps the mixed resin on level.

Two feed the mat strips or pieces into the rollers, and rolls it up on a roller as it is fed out, and then rolls the wetted glass onto the surface.

One person co-ordinates the placing of the wetted surfaces according to a worked out sequence and position schedule.

One or two or three people roll the air out of the applied material.

Using a second pair of guys they could also feed and roll the mat up while the first two guys are placing their mat.

G'day,

Wet out machines are excellent value, but do not work very well with cut material, partly as knitted material tends to stretch and lose shape when wet and under tension, partly as the cut sides tend to fold over and the wet out is uneven. It is easier to use varying widths of unidirectional and trim the edges for the compound shapes of the hull.

All the wet out machines I have used have had steel, not rubber rollers.
Instead of sitting the bottom roller in resin, you get a better job with the resin sitting between dams on top of the rollers. Means less resin is mixed at any one time, so less chance of exotherm. If you are going to put it on a roller after wet out, you need a very slow resin system. We designed and built one for wetting out the tow when we build masts and other carbon components. Picture at http://www.harryproa.com/building_Vis/building_Vis_5.htm.

Until I saw infusion, a motor driven wet out machine with automatic resin dispensing and mixing was the ultimate way to wet out bulk cloth.

Alan, Great to see long, light boats beating short heavy expensive ones, and you are right about the floors.
There have probably been as many boats with balsa core problems as with osmosis, which does not affect vinylester boats, or polyester boats built correctly. Doesn't stop people using balsa, and done properly, there are no problems.

What rig are you putting on your boat? If it is unstayed, could you drop me a line off list (harryproa@gmail.com), please.

regards,

rob

[waikikin]

Rob, thats a neat looking wet out machine, I really like the rubber wheel drive part(wish we thunk of it), ours has a chain drive & some sneaky geometry to open & nip the rollers & an over centre mechanism to dunk an immersion roller into the resin bath, the bracketing for the resin dams on top look just the same as yours. Regards from Jeff.

[Andy]

I think there are always better and faster ways of building boats. So here are my thoughts...

If you want to do things reasonably quickly, you need to streamline as many of the building processes as possible. I reckon a stitch and glue cat, built in female mold frames and with all parts cnc cut would be an efficient way of building. The money you spend on the machining will probably be paid back partly through less time in the workshop (less heating and lighting bills, less epoxy etc through more accurate fits). Build your interior as a series of modules, to be worked on in comfort outside the boat and completed there too. Buy an HVLP spray gun for much faster finishing, and set up a production line for painting. Hire cheap labor for fairing, or figure out how to run a belt sander along rails which span any hollows in the hull. Plan all your joinery so that you can set up a production line and make it all in one session (e.g. enough stock cut and routed for all wood trim) and standardise as much as possible for the same reason. Create jigs for as many parts as possible, and avoid any fancy finishes (15 coats of varnish will take a lot longer than 3 coats of paint...). Basically, be utterly methodical and efficient in everything you do, and remember that a bit of cheap labour can pay for itself in certain situations by really helping the build along.

[Spiv]

Rob is right, osmosis happened in some gelcoats of the past. Modern gelcoats do not have that problem, actually will last longer than two pack paints.
My partner developed an epoxy sensitivity 6 to 8 months into the project: his skin was falling off him and developed asthma as soon as he came close to epoxy (especially curing) i.e everywhere - something I would not wish to anybody.
Wet layup should, and will soon be, a thing of the past. Infusion, RTM, light RTM and a score of other up and coming technologies will eliminate almost all emissions.
VE is my preferred resin, especially under the waterline as it is even more waterproof than epoxy. Secondary bond on VE is also excellent. Some of the concerns derive from old Polyester formulations and incorrect techniques. At half to a third the cost of epoxy, why waste money?

I would discourage amateurs from strip planking, weather using cedar or durakore, just far too much time consuming, both to build and to fair.

I will not use balsa again, call it duflex, duracore or else. Every hole you drill you must drill oversize, fill with epoxy bog, then drill it again: then one wanders where the time goes.... don't do it properly and the balsa will perish in time.
The plumber or the electrician come on board and drill holes everywhere... a screw comes loose on deck: water finds it way in.. You are at your pen and you want to do some minor mods: get the scales out, weight the epoxy, wait till it sets. If you only knew how often I wished I did not use balsa...

On a technical point, end grain balsa transfers any impact loads straight to the inner skin, delaminating. Foams absorb some of the impact and the inner skin stays put. Anybody not believing try it: laminate a 300x300 piece of foam with 600gsm double bi and do the same on a piece of balsa of the same thickness, put them across two bricks and hit them, gently at first, then a little harder with a hammer. You will see that the balsa will fail much quicker.
If you do what the balsa advocates say and use thinner core, then the results are even worse.
Someone mentioned Polycore, which is similar to Nidaplast; the stuff is even more impact resistant - and much cheaper - than PVC foams. Still, don't think that it is the best core as its flexural strength is less and you need a thicker core, but this is perhaps better discussed on another thread.

One more point: if you want to build a quicker boat look closely at your furniture. Round lounges and seating might look pretty, but they require a LOT more work as well as being utterly impractical as you will not be able to take a nap on them weather you are at anchor in a beaut spot or on a long crossing.
Build all your furniture on the shop floor, fair and prime it, then take it on board, trim the edges and stitch it in.
If you can, buy cockpit and saloon seats, basins, chart table, cabinets even the cross beam from a builder that has molds. Yes it will cost you some money, but how many months of joy will you gain?

[Alan M.]

You need to de-core and seal hull penetrations whether the core is balsa or foam though, so I can't see that being a valid complaint.

I've tried hitting Duflex with a hammer, and apart from being amazed at just how tough the stuff is, I found that it was the side that I was hitting that got damaged - pretty much as you would expect, it eventually dented and then the laminate started to break up. It didn't transmit the impact through to the other laminate by enough to cause delamination or any other visible damage.

[DGreenwood]

Bob Oram
In fact I’ll show you how to build an amazing 50′ pod cat with 3 queen size berths, hot and cold water, toilet system that uses a household loo and will sail at considerably better than 1 to 1.3 wind speed without leaving the cockpit [single handed] for a bit over $200,000 if you have the dedication and about year to spare.

A very interesting statement by Bob Oram from his site. I would love to know how he would pull that off. Anybody ever seen one of his cats like the one described?

[Alan M.]

Bob is currently building a 46 foot podcat for himself. Only part-time, so it will take more than a year, but certainly if you took his approach, which is a minimalist fit-out, and don't try for a "showroom" finish, you could achieve exactly what he describes.

[Spiv]

Alan,
I know you need to decore both, but you don't need to be so particular with foams If you don't need to screw in the hole, you might just leave it as it is; this is a great advantage.

I know that Duflex is tough, I uses $20,000+ in my boat!
For the last 3y I have been consulting in the composite industry and carried out tests on many flat panels with cores such as Balsa, Divinycell , CoreCell, Rohacell, Soteco foams, Nomex, Polycore and more, as well as different reinforcements and resins.
Every combination has pro and cons, but trust me, end brain balsa transmits impact loads to the other skin more than other cores.
Do try same laminate, same resin, same thickness and see. Use 80kg foam (close to half the weight of Balsa) and note the difference.:)

[rob denney]

Alan,
I know you need to decore both, but you don't need to be so particular with foams If you don't need to screw in the hole, you might just leave it as it is; this is a great advantage.

I know that Duflex is tough, I uses $20,000+ in my boat!
For the last 3y I have been consulting in the composite industry and carried out tests on many flat panels with cores such as Balsa, Divinycell , CoreCell, Rohacell, Soteco foams, Nomex, Polycore and more, as well as different reinforcements and resins.
Every combination has pro and cons, but trust me, end brain balsa transmits impact loads to the other skin more than other cores.
Do try same laminate, same resin, same thickness and see. Use 80kg foam (close to half the weight of Balsa) and note the difference.:)

G'day,

Any chance we can see any of those results?

regards,

Rob

[Fanie]

I have a question please -

Do one want the foam to be the structural strength, or the fiberglass - if you build using foam instead of wood ?

If one uses a foam that is structurally not strong enough, but could assist in the initial hull forming, and if blocks of this foam can be removed after the hull is formed so it looks like a big 'honeycomb' that can be glassed over on the inside that should provide structural stiffness. The removed blocks can be trimmed and re-fitted and again fiber glassed over. Should make for a very strong and stiff ie hull, no wood.

Has anyone considered using PCB fiberglass (without the copper of course) ?

[Alan M.]

Alan,
I know you need to decore both, but you don't need to be so particular with foams If you don't need to screw in the hole, you might just leave it as it is; this is a great advantage.



I'm not sure what you mean by this. But if you drill a hole in a foam core you need to de-core and seal it to keep water out - just the same as for balsa. And it really isn't that much of a hassle IMHO.

For internal electrical and plumbing runs I am installing conduit where required. Where a conduit passes through an internal bulkhead I have simply glued it in to seal the core.

A builder of a Schionning Wilderness 1230 told me that he got quotes for the standard balsa cored Duflex kit, and the same kit in foam cored Duflex. The foam cored kit was not only much more expensive, but it was heavier too. Apparently it required heavier laminates and in some places thicker cores to acheive the same result.

Spiv, do you have a source for more information about vinylester being more waterproof than epoxy? I'm sure there are a lot of people applying epoxy barrier coats to vinylester boats who would like to see it.

[captainjsw]

Hi Simon, I agree with almost all that is posted here. Its not possible to build a large boat singlehandedly quickly. You just need help, which can be difficult to get at the right price. I built a 12.8m Grainger and it took me 6 years and I had some paid help over the last couple of years.

I'm currently building a new catamaran, upside down using DuFlex, one hull at a time, I hope to have the first hull turned by the start of Feb 08 - faired and primed, ready for top coat, and then we will be starting on the second hull. I will be able to give you an exact number of hours to get to this point when we are there - if you are in Perth WA you can come and see it :-)

[AndrewK]

Can time be saved by not having to tape all bulkheads and furniture panels?
What size does the glue fillet have to be in order not to requre a glass tape? Has anyone seen any comparative test data for strenghth of glued only versus glued and taped joints?

[doug kay]

I built a 9 metre ground effect and all the bulkheads were epoxied in using a wood flour mix. It withstood Wima in Ft. Lauderdale when 180 Knot odd wind gusts were recorded, my hulls are of cedar strip and after the hardback was set up the two hulls were ready for faring after 9 weeks or about 325 hours. Cedar strip hulls are enormously strong and light and have the advantage of not needing painting. The trick is to prevent the strips from springing, keep them exactly in line and fair this cuts down the fairing time and effort. If I get a any abrasions I simply mix a bit of wood flour and epoxy then sand it, no paint matching, just a touch up with epoxy.

[captainjsw]

Yeah not sure Andrew and have never seen any data. To be honest the time involved taping bulkheads and furniture panels is quite small - I would say a day at most - get your bulkheads in position and the glass tape ready or fibreglass lengths cut, mix your epoxy and what ever filler you want to use or is recommended. Apply the filler and turn it into a nice shape with your favourate curved scraper. Then before the filler has gone totally hard apply the resin and then the glass tape. Jobs Jobbed. If the filler is still soft the additional resin applied smooths out any unevenness. Move on to the next one. Furniture tape can be very light weight and should be. Same proceedure. Filler - say Qcells, resin and lightweight tape - on to the next panel - That was Easy. Check out my site
http://www.johnwatson.net.au

[catsketcher]

Hello AndrewK

I do not want to open a can of worms because no multis tape all the small pieces of furniture in but I do not think omitting the glass tape on all of the furniture and especially the structural parts is a good idea.

Glass and glue are strong but in different ways. Strength as a concept is a can of worms - that is why engineers have to go to uni. Glass gives the structure toughness that glue alone cannot. For example I regularly glue things to the shed floor with epoxy dabs. They stick well and hold onto the floor tenaciously but I can break them with a quick tap with a mallet.

Epoxy is strong but brittle - glass is strong and tough. When you glass an epoxy cove you increase the toughness of the joint dramatically. Try and rip apart a piece of boat that has a glassed cove - it will be a real struggle.

There is scuttlebutt that a cat builder has decided that glass is unnecessary and hasn't used any in his cat. It will be interesting to see how he goes.

cheers

Phil Thompson

[rwatson]

Interesting idea. Thinking about it, I could be convinced. The bulkheads and furniture would normally all be in compression, unless the whole boat filled up with water, and then a bit of filleting wouldnt count for much.
Glues or epoxys are only good for compressive strength, and if thats all that is required, then it sounds good.
Mind you, I am doing watertight bulkheads in a canoe, where I will need the strength of a fillet with glass, in case big feet or a rush of water put shear pressures on the joints. The same would apply for strategic internal watertight bulkheads I would expect.

[simon]

John,

thanks to everyone for the interesting input.

captainjsw: nice site. I would be interested to know more about your current project and what you have learned from your first, technical speaking.

Does anyone have experience with the building process in aluminium.

In an other thread there has been mentioned that someone built a Tim Mumby 48' design in a year. Anyone knows more about this case?

Apparently Owen Eston is building 43' aluminium hulls in around 3 months time with little outside help

I know that aluminium is relatively heavy and just used for larger cats. I sailed on a 48' Tim Mumby and was impressed by the performance.

Advantages of aluminium construction:
- no molds needed
- no paint on topside
- lot can be precut
- relative low price of material

Disadvantage:
- good and experienced welder needed
- insulation adds extra weight and work
- interior lining needed

Simon

[AndrewK]

Simon,
Owen Easton does a great job, 12 months ago $75K and 6 months of your own time working alongside Owen bought you a 43ft Aluminium cat at the lock up stage. No internal furniture.

[AndrewK]

Captainjsw; nice site, will have a further look.

I follow the same procedure as you do with the addition of peel ply at the end. I am working on my second boat at the moment and certainly will take much longer than a day to tape all of the glued and coved panels.
Also there is huge amount of tape that goes into a 12m catamaran, certainly not an insignificant amount of weight to be saved if not necessary.

Personaly I am very inerested to see real test data showing how much additional strength & toughnes tape adds to a join. I would guess that a reasonable sized cove contributes the greater proportion of the joint strength than the glass. But could be wrong.

One downside of omitting the glass tape would be a reduction in stress transition.

[Alan M.]

I would tape the bulkheads and the larger furniture parts in Andrew. I've had joins which were just glued break due to brittleness, whereas the same join, reglued and taped, is massively strong.

[AndrewK]

Alan,
Are you refering to the chine panel joins that cracked during the hull rollover?

I have a couple of friends that heve been building composite boats for a long time and both think that we are all wasting time taping everything. But both continue to do so as they do not want to take a risk with their insurance.
Both have had experiances where they glued in panels and later decided to shift them and almost destroyed the boats in the process of removing them.

[Alan M.]

None of the chine panel joins cracked, Andrew. They were all taped on the inside.

I was referring to a horizontal brace on top of a seat back, that runs the length of the galley. It had glue fillets only on it, which would probably have been fine, except that when I was sanding the saloon roof, I overbalanced and put some weight on it, the brace flexed slightly and the glue immediately cracked. I ground off the glue and re-glued and taped the join, and now I can stand on that brace if I like. (Although it was never intended to be stood on.)

Another area, which was always intended to be taped, was where the rear gussets from the cockpit roof meet the side decks. I had glued them and was planning to tape them both, but ran out of time and resin after only getting one taped - so I left the other till the next day. Well it didn't get done for the next couple of days, and I was always avoiding that side deck, using the side that was taped, until one time I forgot, and put about half my weight on the deck of the untaped side - the glue fillet immediately snapped. By comparison, on the side that was taped, you could jump up and down on the deck with no issue, as you can on both sides now they are taped.

[captainjsw]

I am going to tape everything that is structural, my view is that the bulkheads and panels are not just in compression, when you are sailing the boat is flexing, just about glued only anything will crack in time. Well maybe a day to tape things is a bit on the light side - thats just me though, I always think things can be done as fast as I can think them, which of course is not the case. I do agree though watch the weight, a fair bit can be added without care, like only tape one side of the furniture etc, and use real light tape. One example I can give is that in a couple of places (on my current boat) - where I only glued ply a hairline crack appeared after a couple of years, now the bulkhead is secured top and bottom so structurally fine but the simple flexing of the panels causes the hard glue line to fail - I've since ground out the glue and added a small fillet of glass tape - nice messy job in a fitted out and painted boat.

Cheers John

[doug kay]

Yes I agree with the tape being needed because of the brittleness of epoxy, I also drill holes around the perimeter of the bulkheads etc. and push glass strands through and then soak them in resin this helps the bonding to the hull.