Building Methods [Archive] - Boat Design Forums

Manie B

09-21-2009, 11:24 AM

Jeez this is so coooool

Manie - since we are in the righteous majority

i loooove it :P

you and i are still gonna go places :D

fact is i can weld, still do little odd jobs myself, and i will most definately build my own trailer for the microcruiser.
This was the trailer for the chigger, which is still going strong !

Your pics are amazing, just very very sad that many of those factories are closed NEVER to open up again. As you know i am a very optimistic person, with my feet on the ground AND an eye on reality. The world will lose boat building skills like never before. SAD

As you know i am an epoxy man who actually doesn't like steel.
I will reveal a bit more later when i have more facts and figures, but the idea at this stage is to build a composite mast for the micro. I strongly believe that a light floating mast is a huge asset to help in turning the boat upright if rolled over completely. The mast must be filled with closed cell foam.

Herman

09-21-2009, 02:34 PM

I had a dinghy (5 meter, 16 ft) with a watertight mast. Indeed this is a great help righting the boat after a capsize. Actually from all the capsizes I have done (many!!!) I have only been able to turn the thing turtle once. Luckily on Lake Garda, so plenty of depth over there, not to hit something.

It is just a bit fiddly to get the mast watertight. Careful planning and careful use of sealant is needed.

Wynand N

09-22-2009, 02:11 AM

What build method do you prefer and why?

cold molded strip ply on frames and stringers. Light and very strong and not constricted to chine hulls only as with glue and stitch method....

rwatson

09-22-2009, 03:26 AM

I strongly believe that a light floating mast is a huge asset to help in turning the boat upright if rolled over completely. The mast must be filled with closed cell foam.

Oooh - be veeery carefull. Foam is quite heavy, and near the top of the mast can make a little boat a bit tippy. Might be better to use an air filled something - bubblewarp?

Petros

09-23-2009, 12:36 AM

I have built 9 skin-on-frame boats, and also other small boats of conventional plank and GRP. I love the skin-on-frame method for these reasons: It is very light, it uses much less materials (cost much less to build), design changes are fast and easy to execute, it assembles much faster than stitch and glue, it results in a tough and durable hull, usually only simple hand tools are required. And for me, unlike GRP, there is no need to EVER handle toxic materials.

All of the boats I have built were under 20 feet LOA (kayaks and dingys, including a 14' sloop), but I know of vessels as long as 40 ft using the method.

It is a very efficient use of materials so it is both light and less costly since less materials are used, there is not as much detail fitting of panel edges, garboard, etc. so it is much faster.

For example a SOF sea kayak would cost about $100-$200 in material cost, and about 100 hours to build (including ripping your own stringers and gunewales from larger stock). finished it would weight about 25 lbs. An equivalent sized SNG sea kayak would take about $600-700 in material costs and about 300-400 or more hours to cut, assemble and finish. And it would weigh about 35 lbs. Installing bulkheads and cargo hatches is easier on SNG, but these add weight and cost and not really normal in traditional designs (but I have installed water tight bulkheads and hatches in skin-on-frame kayaks).

The disadvantage with SOF over SNG I think is that there is somewhat less interior usable space because of the frame (but no less than conversational plank-on-frame), and you are limited in hull shapes because you can not have hollow or concave surfaces.

I do not know why anyone would not consider the construction method other than ignorance. I like the construction method so much I am considering designing a 20' sloop with a small cabin for weekend sailing trips. It would be fast and inexpensive to build, and very light for trailer and launching.

There are a number of sea kayak builders' forums you should investigate before dismissing the method. Since it is not a conventional construction method for most larger boats, you will not find a lot of people on this kind of forum that are familiar with it. No matter what method you choose, do not dismiss this construction method because of ignorance. There are many ancient examples of skin-on-frame boats in many cultures, not just Eskimos. My favorite story is of St. Brendan the Navigator, an Irish monk who apparently built a 36' skin on frame sailboat and made it to North America and back to Ireland in the 6th (?) century with 6 sailing companions. This was long before Columbus and perhaps even the vikings.

Wynand N

09-23-2009, 02:33 AM

Oooh - be veeery carefull. Foam is quite heavy, and near the top of the mast can make a little boat a bit tippy. Might be better to use an air filled something - bubblewarp?

quite the opposite actually. Expanded closed cell Polyurethane foam only weights about 38kg per cubic meter (1000 liters) and that is a lot of foam that will give positive buoyancy of about 987kg in sea water.

An average 27ft boat as Manie mentioned will have about 145lt volume in mast and the weight of that foam will only be about 5.5kg (12lbs) and that foam will be helpful providing positive righting buoyancy where needed most when knocked over.

rwatson

09-23-2009, 05:24 AM

To itemize the question Manie was asking.
There are three methods in question
1) Skin on frame (hull material built over moulds and /or fastened to frames)
2) Stitch and glue (developed panels tacked then taped together over minimal female moulds)
3) Female Moulds or "basket" assembly (compound curved or full developed panels or a mixture of both in a "hollow" substantial set of moulds.

skin-on-frame method for these reasons: It is very light, it uses much less materials

That doesnt make sense to me. Stitch and glue ends up being the same skin materials, LESS the temporary moulds and framing material.

because, as you state later
"The disadvantage with SOF over SNG I think is that there is somewhat less interior usable space because of the frame "

The material list for the two types of hulls would be identical but for the retained frame.

The time taken to build in a female mould system or stitch and glue is significantly less than Skin On Frame - because you don't have to remove the internal moulds to install furniture and fittings. The furniture and fittings *are* the internal moulds.

The other big time waster in building say a canoe/kayak on skin on frame, (especially stripped plank construction), is the painfull cleaning up of the hull interior after hull turning. It is far far easier to fair and smooth a convex (outer hull surface) than a concave (inner hull surface).

Nor do you have to create a temporary suporting structure to keep the hull fair on SOG construction, (after removing internal temporary moulds), while you complete the interior.

You may be keen and experienced in SOG construction, but it doesnt sound like you have had a chance to try the alternatives. You might be surprised.

boat fan

09-23-2009, 10:45 AM

I think it depends in part on the actual design.

http://thecoastalpassage.com.au/tbcat/1.jpg
http://thecoastalpassage.com.au/tbcat/3.jpg

This is really derived from plywood on / stringers on / frame .

That boat could be built stitch and glue I guess , but the prefab flat panel construction used here looks faster to me.
I would pre finish the interior of those panels while flat on the bench ,
except the glue lines .

http://thecoastalpassage.com.au/tbcat/6.jpg

I would love to see a catamaran built that way .

I like stitch and glue guys , it gives nice clean interiors , but all that sanding in tight spots ....yuk !

http://f1.grp.yahoofs.com/v1/0Bu6Sv-Ey570Kc3Ft8YF5nv48rgm6fCgOPpVH2bnav8MAc3LH-hVR8sbXkpBEpiVo5wFONK0qoCRsEs90wsCG7CmoQ-TgL0Vx7TdnQ/MIcro%20Trawler/psn00007.jpg

http://d.yimg.com/kq/groups/12367100/sn/1817527734/name/n_a

Bolger box boat construction....nothing much easier ..( not all can live with the looks ):D

http://inlinethumb26.webshots.com/33177/2103292840088484686S600x600Q85.jpg

I think glued lapstrake plywood is a real alternative to strip planked construction.

Would love to see a cruising cat built that way .It could look real nice.

hoytedow

09-23-2009, 10:49 AM

Oooh - be veeery carefull. Foam is quite heavy, and near the top of the mast can make a little boat a bit tippy. Might be better to use an air filled something - bubblewarp?

Why not foam the near the ends only so as to keep weight down?

rwatson

09-23-2009, 12:36 PM

I think it depends in part on the actual design.

That boat could be built stitch and glue I guess , but the prefab flat panel construction used here looks faster to me.
I would pre finish the interior of those panels while flat on the bench ,
except the glue lines .
....
Would love to see a cruising cat built that way .It could look real nice.

Derek Kelsall has been building cruising cats and small cats using flat finished pre-fab panels for years, with the stringers attached.

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

He used to use plywood, but now favours foam panel

Manie B

09-23-2009, 01:23 PM

My question was a sailboat of approx 8m and i will add to that, say 5m to 9m just to widen the field a bit more.

I do appreciate the comments on smaller builds such as a kayak, but when you start looking around at the many boats (sail and power) that are built SNG you start wondering why not even more?

What worries me is that there are many "newbies" that haven't got experience and are looking at an endless list of "free" plans, and i think that most of us will agree that 99% of those plans are outdated and hopelessly insufficient for a beginner to build without assistance. One of the mayor problems in the current economy, is for ANY designer to prepare a complete NEW set of plans for a beginner is virtually impossible, as it wont pay. Designers simply cannot make a decent living out of selling plans. When you draw as much as i do on CAD you will soon realise that the prices quoted for plans are generally cheap. Therefore the plans that a beginner should look at are those which have good support online. Unfortunately our popular designers are not spring chikens anymore either and the good designs out there are also a couple of years old already. When you look at the ease with which a HUGE build such as Mas's dream cat http://www.boatdesign.net/forums/boat-building/my-little-piece-peace-25962-40.html is coming together and when you look at the endless stream of SNG projects out there, you start realising that many of the current designs on the market today, should be converted / redrawn as female / basket mould type of SNG / taped seam types of builds. There are many of the popular designs out there that lend themselves to this kind of build method.

I have spent DAYS (100's hours) on FREESHIP looking at and comparing resistance values of round bilge designs VS hard chine boats and please believe me that a hard chine - 5 or 6 panel has so little resistance more that for cruising / club racing it makes absolutely no difference.

I am now on my 5 th build (#five) and i have had the good fortune to spend time in some boat yards with very competent builders working with all materials, GRP, steel, wood - and i can assure you that SNG in a basket is fast and economical and light. I know that some folks regard Epoxy and Marine ply as expensive and problematic (toxic) but it gives a strong and very light build. I am also convinced that for the home builder Epoxy and ply SNG is actually cheaper. One point that i MUST STRESS is that i do not favour ANY build method above the other, if you can prove that YOUR method is faster i will change over tomorrow, but that remains to be seen.

I also would like to see some of the more recent designs REDRAWN and re-engineered where the internals and "furniture" etc. is part and parcel of the "honeycomb" structure as per Oram, as a "basket" female mould type of build. Flat panels SNG. For me there are nice designs out there, but the skin over frame just doesn't do it anymore. The big CATs are fantastic in expensive balsa laminates, pre cut panels. Simple cut out and glue together, but if you dont live in that country you simply cant afford it. Unfortunately there is not enough of that type of build research going on for cruising mono's. The world is cat mad and yet the monos have plenty to offer, show me where can you see a MONO build similar to Mas's cat.

anywaaaaaay enjoy your day, supper time here, hot and dusty, Sydney is covered in dust and so is Pretoria, damn why is the sea so flippen far:(

Manie B

09-23-2009, 01:37 PM

boat fan

09-23-2009, 07:13 PM

I have spent DAYS (100's hours) on FREESHIP looking at and comparing resistance values of round bilge designs VS hard chine boats and please believe me that a hard chine - 5 or 6 panel has so little resistance more that for cruising / club racing it makes absolutely no difference.

Yes no doubt about it.

i can assure you that SNG in a basket is fast and economical and light

The basket is wasteful.
Sanding the fillets to a nice finish is a pain.
It`s slow, dirty, tedious work.:mad:
Careful masking , taping and laying of fillets will help a great deal, BUT.....

Sam Devlins boats have nice clean interiors.
he`s a pro in every sense of the word , yet I bet that he does not enjoy the huge amount of fairing and sanding it takes to produce a highly finished product ( which ) his boats are.

It is light as you say.

I know that some folks regard Epoxy and Marine ply as expensive and problematic (toxic) but it gives a strong and very light build.

Absolutely.As above.

All in all Manie I think your`e right about what you say.

The fairing is still a pain. Take a look here , at the work involved just fairing some steps :http://www.mahnamahna.com.au/May%202009.html

As far as Mas and his Oram ......the boat does go together relatively fast , the panels are obviously a perfect fit .
Lovely boat , good choice.

But I think you will find that to finish that boat to the standard it deserves , there is a huge amount of fairing and finishing yet to be done.

boat fan

09-23-2009, 07:20 PM

anywaaaaaay enjoy your day, supper time here, hot and dusty, Sydney is covered in dust and so is Pretoria, damn why is the sea so flippen far:(

Sydney`s dust......It`s moved to where Mas is building ...last night.:(http://images.brisbanetimes.com.au/2009/09/23/749161/IMG_0409-600x400.jpghttp://images.brisbanetimes.com.au/2009/09/23/749284/Gold%20Coast%20159-600x400.jpg

ancient kayaker

09-24-2009, 12:20 AM

Interesting thread. I looked into a lot of different boat building methods, they all had some disadvantages. Stitch methods leave all those little holes with bits of copper wire, and then there’s all the sanding of the epoxy fillets. The finished boat shape magnifies any errors in the lofted plank developments and cutting, and the individual planks are flimsy.

Framed methods increase the weight compared to monocoque construction. I love the look of glued lapstrake and strip-planked boats but I resent the material cost and effort that goes into any kind of mold that doesn’t form part of the finished product. As my boats are slowly getting bigger (there must be a medical name for that) the handling problems of rollovers are becoming more apparent.

For some years I have worked with prefab flat panels - similar to Boat Fan. I found it was ideally suited to smaller boats, and I am looking into how to adapt it for the larger craft that my medical condition requires me to build. Presently I glue chine logs and inwales to the sheer planks while flat, makes ‘em tougher and easier to handle. Flat bottomed boats are very quick with this method. For five-plank construction I also add chine logs to the bottom plank, attach it to the stem(s) and a mold or two, then plane the edges to fit the bilge planks, which are simply cut to fit. Errors in developments are not very important, very little waste, and I can use cheaper glue for all the joints except the last ones, for bilge planks, which are the only ones exposed to water.

Adding internal construction seems a bit of a hassle. Getting a good fit inside an existing body is more difficult, access can be a problem, and I find fitting a bent panel between bulkheads with really tight joints all round can be a real challenge. More skill needed here than building the basic hull.

Therefore I am working on adapting the prefab method to a larger boat with interior construction such as a cockpit. Briefly, I am thinking of building the cockpit and buoyancy tanks first, using those as a mold around which to bend the hull planks.. It seems to eliminate many of the difficulties and objections I have with other methods. I am also looking at rounded bilges instead of hard chine; these will be cross-planked in a lightweight lumber. No doubt it will be a learning experience just like all the other boats were ...

I must just add this: having a live and accessible designer is a huge advantage especially if you are using a different or unusual construction method.

boat fan

09-24-2009, 02:46 AM

I am also looking at rounded bilges instead of hard chine; these will be cross-planked in a lightweight lumber.
.

I`m trying to visualize this ...are you saying you " cross plank " in the traditional sense , how the original sharpies were built , ( planking the bottom across the beam ) ? but " bending" the planks in a curve ?

http://dieselducks.com/Woodducks/bottomplanks.jpg

You could strip plank the curve at the bilge I guess :

http://www.westsystem.com/ss/assets/galleries/Building-a-woodepoxy-sharpie-GalleryPage/_resampled/ResizedImage360302-sharpie8a2.jpg

boat fan

09-24-2009, 03:28 AM

And just as an after thought

here is my "dream boat"

the ultimate live aboard for 2 world cruiser, small enough, light, fast in moderate winds, Honda fourstroke 20 hp outboard, NO TV and other fancy sh1t but it has to be built as SNG in a basket, Epoxy over ply hard chine :D

http://www.google.com.au/url?sa=t&source=web&ct=res&cd=1&url=http%3A%2F%2Fwww.yachtdesign.com.br%2F02_ingles%2Fplans%2Fmc28%2Fclub28-2.html&ei=wh67SraWH5DasQPng_HoCA&usg=AFQjCNFLlvsMam-Js8HGZNvm8KfVn376Lg

Take a look Manie ......may be of interest , check out the construction .........

May be possible to adapt to SNG .

Petros

09-24-2009, 03:31 AM

That doesnt make sense to me. Stitch and glue ends up being the same skin materials, LESS the temporary moulds and framing material.

because, as you state later
"The disadvantage with SOF over SNG I think is that there is somewhat less interior usable space because of the frame "

The material list for the two types of hulls would be identical but for the retained frame.

The time taken to build in a female mould system or stitch and glue is significantly less than Skin On Frame - because you don't have to remove the internal moulds to install furniture and fittings. The furniture and fittings *are* the internal moulds.

The other big time waster in building say a canoe/kayak on skin on frame, (especially stripped plank construction), is the painfull cleaning up of the hull interior after hull turning. It is far far easier to fair and smooth a convex (outer hull surface) than a concave (inner hull surface).

I have no idea what you are talking about here. The internal frame can also become the furniture and fittings. You build the internal frame and it becomes part of the structure, adding strength, so the skin material is lighter. You do not have a lot of fillets to sand, in fact you do not have to glass the inside at all, just seal and paint it. All the fiberglass prep is done on the outside. But I have built without any skin plywood or fiberglass at all, the skin is heavy polyester fabric with polyeurathane sealant supported by stingers. With an external frame/mold it becomes scrap when you are done with it. All the stitching and glueing and fillet sanding of SNG is very tedious and time consuming, there is no equivalent for SOF.

You are the one lacking experience here, I have built using all three methods. A skin on frame kayak or sailing dingy takes about one third the amount of hours to build, and half the materials, than either stitch and glue or strip built. You also appear to think that strip built is interchangeable with Skin-on-frame, totally different method, different structual design, different process.

boat fan

09-24-2009, 04:01 AM

The internal frame can also become the furniture and fittings. You build the internal frame and it becomes part of the structure, adding strength, so the skin material is lighter. You do not have a lot of fillets to sand, in fact you do not have to glass the inside at all, just seal and paint it. All the fiberglass prep is done on the outside...... With an external frame/mold it becomes scrap when you are done with it. ...... All the stitching and glueing and fillet sanding of SNG is very tedious and time consuming,.......

Agreed Petros , I think you pointed out the major disadvantages of SNG.

The thing I DO like about SNG s the nice radiused clean corners.
Too much horrible , dusty , tedious sanding for me afraid .....:(

boat fan

09-24-2009, 04:52 AM

http://www.boatdesign.net/gallery/data/500/medium/Boat_Hulls_turned_over.jpg
http://www.boatdesign.net/gallery/data/500/medium/hulls_1001.jpg

rwatson

09-24-2009, 07:28 AM

I have no idea what you are talking about here. The internal frame can also become the furniture and fittings. You build the internal frame and it becomes part of the structure, adding strength, so the skin material is lighter. .

No all SOG designs leave all the the framing inside the fininshed boat - there can be a lot of temporary inserts.

Even so, you have to build a very complex and awkward "skeleton" to support the relatively lighter skin.

Much of the skeleton serves no purpose than hold the skin apart, and take up room - as you say yourself.

It is crazy to stick the strength in the internal frame, and leave the bit holding the water out thin. It is much better to maximise the skin strength, because thats what keeps the water out.

Thats why cars no longer have chassis - much more efficiency of materials and labour.

You do not have a lot of fillets to sand, in fact you do not have to glass the inside at all, just seal and paint it. .

If you use peel ply in SNG, that sanding is very much reduced. With SOG you have all the little angles in the interior that are hard to finish (even with only painting), have taken a long time to cut and assemble, sharp angles to capture grit and water, and as you say yourself - take up room

But I have built without any skin plywood or fiberglass at all, the skin is heavy polyester fabric with polyeurathane sealant supported by stingers. With an external frame/mold it becomes scrap when you are done with it. All the stitching and glueing and fillet sanding of SNG is very tedious and time consuming, there is no equivalent for SOF. .

True there is sanding to do, but that bit of sanding is offset with the much more complex framing and internals (stringers and bulkeads) required for SOF. The other benefit of having fibreglass on the inside as well as out, is extra strength, requiring less framing and furniture, but mostly, better weather protection.

For small boats with only paint on the interior, the plywood is far more prone to degradation from moisture.

I have built using all three methods. A skin on frame kayak or sailing dingy takes about one third the amount of hours to build, and half the materials, than either stitch and glue or strip built. .

75.4% of people make up statistics on the spot.

You have not provided any hard figures. You also combine stitch and glue with strip planking - (they are NOT comparable you know!) How you can say that strip planking has the same build ratio as SNG, just doesnt make sense.

How a ... say .. SNG 16 ft finghy uses less material and is less labour than an equivalent 16ft SOF dinghy , just doesnt compute.

I think someone referred to one of the leading SNG builders on this thread - Sam Devlin. he quotes several examples in his book, of the efficiencies of SNG over SOG, including labour, materials, and superior longevity.

You also appear to think that strip built is interchangeable with Skin-on-frame, totally different method, different structual design, different process.

Strip plank *is* Skin on frame - its just that the skin is made up of much smaller pieces.

The similarities are -
Limited access to the interior until rollover
Even more sacrifical frames

But if you want to leave that out, I dont mind for the sake of this discussion.

boat fan

09-24-2009, 10:14 AM

Strip plank *is* Skin on frame - its just that the skin is made up of much smaller pieces.

No , it is not.

After the hull is stripped , the exterior is sheathed with glass / epoxy
or dynel or polypropylene cloth. After that it is usually turned and all moulds and temporary frames are removed.
The interior is sanded and sheathed with glass / epoxy .
what you have now is is essentially a monocoque shell .
The skin is largely self supporting.

It is further strengthened by bulkheads , floors , bunk flats , cupboards
( built in furniture ) and decking / superstructure.

-- --- --

A skin on frame is essentally a hull that relies on a combination of sawn or laminated frames and stringers to support the " skin " or planking.

The " skin " ( or ) "planking " only keeps the water out.

It is essentially NOT a monocoque shell like a stripped hull.

The two are in fact fundamentally quite different.

A hull built using stitch and glue construction is by its nature similar to the stripper hull.

Both the strip built hull and the stitch and glue are further strengthened by the addition of bulkheads , furniture etc as mentioned before.

The skin on frame relies on the FRAMES AND STRINGERS to gain it`s strength.
.
The two are worlds apart .

( It was I who mentioned Devlin ).

Manie B

09-24-2009, 01:32 PM

Ok just to answer a couple of questions

The wire holes left behind of SNG on my little chigger drove me nuts, way too much work and even though i had the panels CNC cut, i hated the "wobbly" construction of SNG. I tried different types of wire - all lousy IMHO. Difficult to get in between the wires to fillet, so you end up doing fillets in stages. You cant go near the boat with wet fillets, so you wait. Extra work - extra frustration, lost of sanding. I experimented LOTS on the chigger with holes, wire, layups, sanding methods, sanding machines, epoxys, and everything else. One thing that worked well from day one was "bedding" the furniture and stiffners down onto the skin, this worked very well. No gaps, where water can creep in and rot. Easy to fillet and sand. A clean job.

With the Jarcat hulls AND the basket frame i was in heaven. Just the minimum of screws thru the panels into the frames to hold it in position firmly, and no where near where i was going to fillet. All panels cut by hand jig saw. CNC cutting is very expensive and after riding back and forth and explaining to the CNC folks what i wanted, i realised that i might as well loft and cut myself - IT WORKS. Bedding stiffners and furniture once again easy.

But i was still not happy with my fillets - too much work - NEW EXPERIMENT

http://www.boatdesign.net/forums/boat-building/manies-shiny-dinghy-26675.html

here i realised that filleting is part ART part SCIENCE part experience
make your own tools - filleting is like welding PRACTICE
i now lay a fillet down ONE SHOT - - NO SANDING !!!
mix paste and put in plastic bag
small hole - squeze out like toothpaste carefully, like "welding" into corners
scrape smooth with "putty" knife
wait 2 hours to "tacky"
paint light coat of epoxy - roll out fibre cloth - saturate, work in lightly with paint brush - roll on peelply
next morning JOB DONE - EASY PEASY
light quick sand to clean up only

that is why i built the Portuguese Dinghy, to prove to myself that i can do it,
one shot - easy - clean and fast. I hate doing things over, so i force myself to come up with things that work fast and easy. I dont have help, work alone, and obviously DONT LIKE SANDING :D

so yes here we are now
the basket holds things firmly and accurately in place
fillets go down easy and fast with the minimum of fuss
install furniture and stiffners and bulkheads
glass inside
roll over - glass outside
sand and paint
get onto the water
drink beer :D

Oh and by the way folks
the basket for the microcruiser is 99 % finished and ready for ASSEMBLY
keep you posted

:D :D :D

Manie B

09-24-2009, 01:44 PM

oh and VERY VERY important

with skin on frame you have a LOTS of screws holding the skin down
they have to be smoothed down and filled, metal expands, bump on surface

with the female mould - basket assembly - NO SCREWS - NOTHING

taped seams - glass inside - glass outside - paint - finished !

Manie B

09-24-2009, 02:37 PM

i knew i had a pic somewhere

here it is - a screw nightmare to me - endless filling and smoothing and sanding
this is that Welshford boat that the guy built and fell asleep on the maiden voyage and crashed on the rocks

i have seen pics of stainless screws that had simply vanished after a couple of years, you think that screws are holding the skin on frame mean time there is nothing

http://www.jwboatdesigns.co.nz/plans/sundowner/updates.htm

ancient kayaker

09-24-2009, 06:49 PM

I`m trying to visualize this ...are you saying you " cross plank " in the traditional sense , how the original sharpies were built , ( planking the bottom across the beam ) ? but " bending" the planks in a curve ?
...
You could strip plank the curve at the bilge I guess :
...

Yes, I plan to cross plank rather than strip plank. The planks will lie on top of the chine logs at each end. This should be stronger than strip planking but heavier of course. The extra strength is welcome at the bilge which gets much of the abuse on water or land, in my experience. The weight penalty is acceptable for a small radius bilge.

However, the planks will be straight not bent; the inside surface will remain straight and the outside surface will be cut to form the curve. The cross section will therefore be an ogive for a circular chine; a 3/4" thick plank will handle about 3.5 " radius, average thickness about 1/2" - about the same weight as 5/16 ply. By adopting an elliptical cross section I can either reduce the weight or increase the width of the bilge. I am still playing with different ideas at this point.

boat fan

09-24-2009, 06:52 PM

Fairing SMALL fillets is relatively easy Mani....:D

With some practice you can get great looking ones that require little
sanding . I ground various larger spoons , pvc pipe and other objects and got good results. just like you say....BUT....

As soon as you get structural fillets in of magnitude like , for example Masalai`s build ....the whole game changes......drastically.

When you lap progressive layers of tape 6 , 12 , and 18 inches wide the
nightmare begins....fairing and feathering taped joins 18 inches into a panel is awful. LOTS of bog ( which you will NEVER lay down ONCE ) but probably three or four times then sand before its fair.

Building dinghies and toy boats is easy.The " big boys" are not.http://www.boatdesign.net/gallery/data/500/medium/P1000848.jpgFairing THIS for eample ....OH BOY !!!!!!

The taping of larger boats with multiple layers of wide tape gets expensive tedious and slow. Peelply helps. It also gives you the best looking boat IMHO . if you put in the time money and effort.

boat fan

09-24-2009, 06:54 PM

Yes, I plan to cross plank rather than strip plank. The planks will lie on top of the chine logs at each end. This should be stronger than strip planking but heavier of course. The extra strength is welcome at the bilge which gets much of the abuse on water or land, in my experience. The weight penalty is acceptable for a small radius bilge.

However, the planks will be straight not bent; the inside surface will remain straight and the outside surface will be cut to form the curve. The cross section will therefore be an ogive for a circular chine; a 3/4" thick plank will handle about 3.5 " radius, average thickness about 1/2" - about the same weight as 5/16 ply. By adopting an elliptical cross section I can either reduce the weight or increase the width of the bilge. I am still playing with different ideas at this point.

O K....gotcha :D

ancient kayaker

09-24-2009, 11:55 PM

It was watching a friend of mine suffer through building a S&G canoe that led me to develop my method. He worried about the plank developments because he knew that the design had not actually been built before, lofting was a pain, cutting the planks was agonizing, drilling all the little holes and trying to get the hull shape right by adjusting the stitches was time consuming, and the stitched boat sat for a couple of weeks before he felt ready to apply resin because it didn't turn out according to the lines. I'll omit his experiences of sanding the fillets because this is, or should be a family web site.

He had built at least 2 boats before! No doubt working with a kit is much easier and less of a bother, but I got the message. I had never attempted boatbuilding before so I researched what other methods there were and put together what I thought, at the time, was a composite. I wanted nothing to do with lofting, stitches, fillets and sanding, and when I found out how expensive epoxy was I minimized that as well. Others have also thought of this method but it was new to me at the time.

He still hasn't finished the boat, he can't decide what to do with it. In the meantime I am finishing up my 5th boat. I worry that I am slowing down in my old age!

masalai

09-25-2009, 12:53 AM

Manie, Just went quickly through your thread, and on my project:
* The build used 6 "female frames" and they were also used for the other side by turning each frame 180 degrees on the same mark along the hull centreline... They are now available to the next builder at a heavy discount. (they are re-usable)... - No strong-back, just a line marked on the concrete, for the centre of the hull and at the appropriate marks, a squared off line to position the frames...
* LOTS of gyprock fastening??? type screws were used to temporarily hold the DuFLEX in place whilst the internal filleting/glueing set and then REMOVED all the screws and to be used again on other parts... (removing them also when finished)
* The 3 main bulkheads were placed at this time (or were there more? - can't remember...)
* The hulls were turned bum up and cloth epoxied in place & immediately epoxy-wet-out the thin underside ply-layer on the "flat bottom" using Gravity clamps, (lots of heavy things), added more epoxied on cloth, then the rest of the external joins were glued, epoxied, bogged, faired - - - then 50% copper dust and epoxy mix applied below the waterline marks, rolled or spatula on, - - - and undercoat for the above waterline area (a quick process that was not very "painful" with no long board slavery, just a quick 'passover' with air driven orbital sanders or the angle grinder with a soft pad and Velcro-ed sandpaper... The bow sections were bogged up using electrical conduit and filled with epoxy/micro-balloons outside, and the bow sections inside were filled with tapered DuFLEX and filleted in whilst the hulls were rolled onto their sides for easy access... The rest is covered adequately in the photographs... The hulls are a lot more accurate than many moulded production builds but the important part is both should be in line with the "keel" centreline and set square across the hulls... Minor variations are not relevant so long as they are not noticed by any "critics" - - (I have seen Monos under 30ft that are about 3 cm out along the centreline, and If they were not being measured at the time nobody would have been the wiser in appearance or cruising performance - except a sometimes curiosity as to why she points better this way than that in some conditions?)...
* All joins were filleted and shaped with a variety of spatulas then taped and epoxied, with peel-ply rollered on using the little metal rollers, bogged and sanded inside and out... The peel ply on the big areas of the DuFLEX was not removed until work was to be done on that area, this kept the surface clean and ready... Likewise all filleted joins etc., were taped and epoxied then recovered with peel-ply and rolled with those little metal rollers (occasionally burn them to clean them up and whilst hot hit with water from the hose to make them as good as new)...
* When the hulls were joined to make a "cat" lots of measurements and "nudging" was done to ensure true alignment (again centrelines were drawn on the concrete, squared off and marked at key reference points...) the internals were flexible and because of the glueing technique, do not "force" the internals into place as that will distort the outside view of the hulls and the glue is best if there is a gap where you can force it in with a spatula... To hold stuff in place use a screw to temporarily align whilst the glue (epoxy & micro-spheres) cures, then REMOVE THE SCREWS :D:D:D
* Later, as you remove the peel-ply, you should be pleased to note that the surface requires minimal touch-up, - - filling screw holes and the occasional careless bit needing a brush with the friendly angle grinder, THEN apply epoxy with a spatula/squeegee to seal the surface then bog/sand and undercoat with hi-build ensuring there are no "pin-holes" PERIOD........ As the paint or other undercoats will never fill these and the build will be leaky.... DuFLEX is never certified as waterproof, It is up to you to ensure ALL micro holes are filled and closed before and after final sanding and before undercoat and then final paint.... NEVER EVER put a hole through without sealing the area by removing the foam/balsa & filling the cavity with a sausage of tape soaked with epoxy completely expelling ANY and ALL air bubbles... when cured, then, make sure the hole is into the epoxied-in tape... and seal that as the screw/bolt is tightened... Better instructions are to be found in the Scrumble Project... It all sounds tedious but as you have seen goes together very easily and quickly, and by having built-in furniture is light, convenient and very robust...

themanshed

09-26-2009, 02:38 AM

New method foam on female 1/2 mold, Carbon Fiber, Vacuum bagged. Building light weight 20' trimaran racer.

boat fan

09-26-2009, 04:46 AM

http://www.boatdesign.net/forums/attachments/boat-building/35478d1253947061t-building-methods-p1010085.jpg

Looks FAAAAST :D

rwatson

09-26-2009, 05:09 AM

New method foam on female 1/2 mold, Carbon Fiber, Vacuum bagged. Building light weight 20' trimaran racer.

Is that just plain foam pegged into the moulds ?

If so, what brand of foam ?

Looks like a great solution to many building problems

rwatson

09-26-2009, 05:13 AM

New method foam on female 1/2 mold, Carbon Fiber, Vacuum bagged. Building light weight 20' trimaran racer.

Is it my eyes, or a bit of a fairing problems ?

masalai

09-26-2009, 05:28 AM

By gosh I think he's got it... I agree seems a bit out, bump and hollow where one should not be? - - Looks like a somewhat slow and expensive process & I hope the effort achieves the foam / carbon result desired... - that you achieve that extra one or more tenths... That technique, to me, is dedication to seek the ultimate fraction of improvement... My desire to race and skill level in sailing could not justify such effort/expense...

rwatson

09-26-2009, 05:43 AM

Well, no. It looks great .... IF

1) You can glue the strips and the glue sets quicker than 6 hours -
2) Cutting of the foam is quick and accurate - like running it past 6 razor blades.
3) You can put a stiffening layer on the foam without deforming the planks.

My guess is that a stiffening layer has been put on a panel if foam, and *then* the strips have been cut and glued.

I am very excited to see this, as this is the technique I have been fretting over for my next project.

Very exciting

Pericles

09-26-2009, 06:04 AM

Manie,

I have assembled a collection of books on the subject of epoxy/ply composite boat construction, including Sam Devlin, http://www.devlinboat.com/stitchandglue.htm Ruell Parker http://www.parker-marine.com/parkerlivro.htm Renn Tolman http://www.amateurboatbuilding.com/articles/design/tolman/skiff.html as well as the Gougeon Brothers tome. http://www.westsystem.com/ss/ There are others. Some of the answers you seek can be found within them.

Like you, I applaud Jacques' work. http://bateau2.com/index.php?option=com_content&view=article&id=173&catid=74&Itemid=9 There are so many variations. http://www.multihulldesigns.com/post_apocalyptic_boatbuilding.htm

In the end, there can be only one. :D :D http://www.yachtworld.com/leaving_yw.cgi?url=http://www.vicemusa.com Just wood and glue. :p

Perry

PS This method does work. http://duckworksmagazine.com/03/r/articles/glass/bottom.htm

themanshed

09-27-2009, 08:47 AM

The foam is Divinycell foam for boat building. It is edge glued and I cut a cove and bead on the edge. The cove and bead allows the strips to follow a curved hull shape and not have large gaps in the seams. The ends are butt glued. The strips are held in place by drywall screws until the glue is dry. The set time is up to the glue you use. I happen to use slow West Systems because I live in the tropics and do not want it to set while working. Once the glue is dry you can remove the screws. I cut the foam into 1.5 inch strips for this projects because of the tight compound curves. The foam comes in 4’ x 8’ sheets like plywood. I treat it just like wood – rip it on a table saw, use routers, sanders, and it could be cut with a razor if you wish.

You work with the foam bare (that is the foam is bare you could be if you wish) then it is fared out and glassed up – no stiffening layer the foam is somewhat ridged but yet flexible in strips and heat formed if needed. The strips can be vertical or horizontal. More costly then even proper marine plywood, easier to work with, compound shapes, will not rot.

In the picture the end has a “run wild” as I had one more station to add for the stern section. The foam would not bend that angle so it was added later. A few wows and hollows perhaps. The great thing is that they get fared out on the foam, a little filler if needed, then glassed over. So you can have a very fare surface with out a compromise of strength and not have to do it by sanding fiberglass. Basically you are replacing the wood with foam. Here is my website if you want to see more http://www.themanshed.net/tms-20-trimaran.html (http://themanshed.net)

themanshed

09-27-2009, 09:16 AM

The first view was a working view of the process here is finished view of the foam ready for bog and glass, and building the stern after cutting off the run wild. As you can see this is a very tight complex curve that the foam can bend to it and only drywall screws hold it in place.

Remember the outside needs to be fared out and glassed also. This method can be done without vacuum bagging and using E-Glass but in case of a race boat vacuum bagging and carbon is best.

Vacuum bagging is not too bad anytime you use more then one layer of glass it is best to bag it to get the air out and less resin is stonger after the wet-out. Anyway I just want to add some food for thought. By the way this is a Kurt Hughes design that I had Kurt modify I like his CM method it just is not for this boat because of the shape.

Cheers!

rwatson

09-27-2009, 10:04 AM

Enjoyed the site. Many thanks for that info. Very interesting.

Couple of things that drove you mad, I found myself.

Get a really good jigsaw (that B&D el cheapo caused a lot of probs - I know) - a bandsaw is even better

Use MDF, not pressed wood for moulds (if you can get it there) so that you dont have to fill the edges with bog.

One thing I am dying to try, is to put glass sheet on the outside of the foam so it is self fairing.

Manie B

09-29-2009, 03:24 AM

Well gents, it sure was nice to get an "update" on current opinions and views. For me it was interesting to see were the different techniques are used and by whom and for what. Thanks for all your input. As some of you have probably realised i am going for the "basket" method which is actually similar to themanshed, just a different core. I will update when i can, and then you will have the opportunity to see first hand http://www.boatdesign.net/forums/boat-building/manies-microcruiser-27869.html my take on the method using locally available materials.

Keep in mind that in our third world country we can only use what is freely available, i simply cannot take the risk of using something and then find out in 6 months time that i have to switch suppliers and/or materials. Irony is that epoxy, marine ply and 2pack paint, comes to the same sort of costs as multiple layers of glass, polyester and gel coat.

enjoy :D