The Blasphemy Project

[Peter Jacobs]

I'm STILL thinking of building a glued clinker plywood Folkboat, and have outlined my ideas at http://www.islandnet.com/~pjacobs/tbp.htm

Feedback anyone? ... as he runs for the fall-out shelter smile.gif

-Peter-

[imported_Steven Bauer]

Sounds pretty good to me. Can I come for a sail when you're done?

Steven

[ishmael]

APPROVED! ;)

The main disadvantage to this method, as I see it, is its repairability. If you hole it it's going to take considerably more work to repair. If you happened to be off Belize when it happens, the materials might not fall so close to hand.

But that's minor.

Why the ply floors?

Best of luck,

Jack

[john welsford]

Not blasphemy at all, there were quite a few built in the 60s and 70s in the UK from half inch ply planks. At least one sailed out here to NZ which suggests that the construction method works ok.
JohnW


Originally posted by Peter Jacobs:
I'm STILL thinking of building a glued clinker plywood Folkboat, and have outlined my ideas at http://www.islandnet.com/~pjacobs/tbp.htm

Feedback anyone? ... as he runs for the fall-out shelter smile.gif

-Peter-

[Meerkat]

Iain Oughtred's "Grey Seal" at 22' isn't that far off a Folkboat in size and it's done in glued lapstrake alone with some laminated frames. I suspect his rumored "Great Seal" might be similar and that's (rumored to be) 25' or so.

[Leon Steyns]

Sounds very interesting and well thought of!
If I may comment, I'd go for Okoumé ply instead of Meranti. It will be more expensive, but if you'd take Shelman warranty ply (for example) you will gain both weight and strenght. Added value is that this kind of ply is easier to work with. Availability might be a problem, though. Good luck on your project!

Greets, Leon Steyns.

[DavesFlatsBoat]

Cockpit and Cabin Sides: 19mm (3/4”) 13 ply Marine Meranti plywood (BS1088), fiberglass and epoxy sheathed Expecting Naval gunfire? Looks like an armored bridge!

But love the look, so approval here!

[ahp]

After the original JESTER was lost a replacement Jester was built using cold molded construction. She was stored over the winter at the Museum of Yachting in Newport RI a few years ago. I saw her from the outside, but was never in her. Jester used the Folkboat hull lines, but a different rig. Perhaps you should reseach this. If you need some more leads, contact me.

[Peter Jacobs]

Leon:
From what I've been reading Meranti is the heavier, more durable wood, less prone to rot than Occume. Did I get my species mixed up?

DavesFlatsBoat:
3/4" is the thickness specified in the Folkboat plans for cockpit/cabin sides. The cloth and epoxy is to keep maintenance down. Being a frequent border-crosser I guess that might help with Naval gunfire, too smile.gif

John:
1/2" planking, you say. That's interesting. I wondered about using a thinner than spec'd plank as plywood is stronger than red cedar planking.
I'll get expert advice on that one before laying my $ down.

I appreciate all the feedback. If this proceeds I'll be getting professional help. But I've let a year go by already and still can't make up my mind. :rolleyes:

[Keith Wilson]

GREAT name for the project! It should be a really fine boat.

Scantlings at first look seem definitely on the bulletproof side. In my limited experience, plywood planking is usually made about 2/3 the thickness of regular wood. The Meranti I've used is definitely heavier and stronger than Okoume. From what I read, it's less likely to rot, but I'll let you know in 20 years or so.

[ 01-15-2003, 05:17 PM: Message edited by: Keith Wilson ]

[Leon Steyns]

The reason I picked Okoumé over Meranti was that this particular brand gives 20 year factory warranty against delamination (provided the edges are properly sealed) and uses higher quality veneers. Since the construction specifies epoxy/glass, I presume the overall strenght of the hull lies in the composite structure, not the strenght and weight of the wood. But I'm not an engineer nor naval architect, so I just followed the designer's suggestions in my case.

Greets, Leon Steyns.

[TomRobb]

How, exactly, do you plan to glass a clinker hull? The laps will prove awkward, IMHO. Glass is not necessarily the answer to life's problems.
The ply ought to be quit sufficient unless the mentioned gun fire is anticipated :D

[Peter Jacobs]

Tom,
I don't recall mentioning glassing the hull, but it can be done ... one strake at a time. I believe "Alistego" is done that way at http://www.alistego.com/enm_plank.html
It's shown best on the 11th picture from the top.

[ 01-18-2003, 12:13 AM: Message edited by: Peter Jacobs ]

[john welsford]

In my own design work I would specify a boat of the Folkboats size, weight and intended usage in 1/2 inch . Not so much for structural strength but for resistance to puncture against docks , piles and so on. I note that these older boats use an overlap of only about twice the thickness of the ply, and rivet as well as glue them, they are standing up to usage very very well.
I would not use Occume or Gaboon plywood in any boat that was to be moored , the stuff is listed by Richard Jagels in WoodenBoat ( among others) as non durable, and although it seems to survive in most cases that is more a credit to the paint systems rather than the plywood.
One of its problems is that it is so soft that it is easy to dent the surface, breaking the paint film and letting water in behind, water + Occume = rot.

JohnW

[Leon Steyns]

John,

Please note that I mentioned the Okoumé ply as part of the composite structure. I would never build a boat with plywood without epoxy and a supporting (glass)fibre! Plywood as the core material for a composite is no longer equal to wood (although it looks the same).

Greets, Leon Steyns.

[On Vacation]

I don't think anyone markets Okoume plywood as being tough. It has uniform layers and the topcoat is more for the finish job. Whether its tough on docks plays very little if any on marketing issues. In uses that call for the use of it, most of the time it is glassed. Yes you can use lesser priced wood, but many other issues come into play with its use. Remember the lumberyard skiff job?

[ 01-18-2003, 07:00 PM: Message edited by: Oyster ]

[Hwyl]

There was a boat built in the 70's and early 80's in Holland called the Waarschip 740.(7.4 meters) that is multichine lapstrake. It would be interesting to see how these held up. I sailed one and ended up losing the mast and cabin top (a long story including three kinds of bar, better suited for another post and for when I am more comfortable with this forum)all in all though they were fairly seaworthy and fast and much bigger feeling than a Folkboat. I'm sure that as they were built in Holland the ply was Bryunzeel (hope I spelled it correctly). There is a nice link here http://home.wanadoo.nl/f39/pionier/pionier.html .
One thing to remember about clinker ply is that you are only gluing to one face of the ply (on the non chamfered sheet (unless you have a plan to plane or rabbet both mating surfaces), so ultimately you are depending on the glue apllied in the factory. It seems from the Waarschip construction pictures that there are stringers inside the laps, with mechanical fasteners. Then you run into the problem of the stringers being water collection gullys

[CK 17]

I think a clinker ply hull may be glassed by using cab-o-sil and and epoxy applied in a radius under each lap. I would use a popcicle stick for this, or maybe even a tonge depresser. The outer edge of each lap can be rounded. I think glass will go around a radius of as small as 3/16 of an inch.

What do you think?

Joe Schena

[ 01-18-2003, 09:48 PM: Message edited by: joe schena ]

[Tomcat]

I am really not all that happy about the idea of clinker plywood boats of size, that aren't glassed, because I just don't trust those edges to stay sound. once the water gets in it isn't good whether the boat rots or not. Grey seal is trailerable to some extent, so in that size at least maitenance is a posibility, but I would prefer not to bother.

The edges could be glassed, but unless the glass is actualy continuous, it isn't going to really seal, fillets will pop within a few years, unless the glass overlaps them. By the time the boat has all this junk on it, it is likely to look like a GRP boat anyway.

I would either build it all original woods, or go for composite. Strip planking would be far and away the fastest, and probably cheaper than the gigantic amounts of ply you would need to bend those curves.

Let me also say from long and happy association with scarfs in ply that they have a way of acerting themselves. The wood looks weird in a clear finsih, since it is veneer, not sawn, the scarfs stick out in a natural finish, because the feathers pick up a different hue. Under paint, or glass they print through, and on frosty mornings they show up in the pattern of frost or condensation.

When I tried to get Nigel Irens moving on Roxanna plans, he mentioned that he was against my replacing the engineering of the metal keel with that of a lead one. I was surprised for my part that he had speced the keel in cast iron, since he is a big time fast boat guy, and in my mind the cast is old fashioned. He felt it offered overwelming advantages, in terms of structure, grounding, and hanging the CB. An education for me. There may also be some of this in his WB article.

[Seppo]

Hi

Sometime in '70s and/or '80s some people over here built quite a few folkboats in cold molded way, so keeping the hull shape etc but having no lapstrake structure... I have no idea how the boats fare nowadays, IIRC they were built and used in lake areas, I haven't seen (or noticed) any here on the seacoast.

So if you think of building a folkboat lookalike, would cold molded be a possibility? It would be a lot easier to glass over, anyway.

BR
Seppo