Building Methods

[Manie B]

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...er/updates.htm

[ancient kayaker]

Originally Posted by boat fan

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]

Fairing SMALL fillets is relatively easy Mani....

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.Fairing 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]

Originally Posted by ancient kayaker

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

[ancient kayaker]

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]

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
* 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]

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

[boat fan]

Looks FAAAAST

[rwatson]

Originally Posted by themanshed

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]

Originally Posted by themanshed

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]

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]

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]

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/a...man/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=...id=74&Itemid=9 There are so many variations. http://www.multihulldesigns.com/post...atbuilding.htm

In the end, there can be only one. http://www.yachtworld.com/leaving_yw...w.vicemusa.com Just wood and glue.

Perry

PS This method does work. http://duckworksmagazine.com/03/r/ar...ass/bottom.htm

[themanshed]

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

[themanshed]

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!