Have I reinvented the wheel again?

[sailorjim]

Hello All
After watching a stitch-and-glue tutorial CD, I thought "there must be a better way"… So I got a 310x155 cm sheet of 4 mm Oukoumé and, instead of cutting it into a thousand pieces and stitching it up again, I cut along about a third of the centerline (long axis) and bent it into a « hull » shape (there’s no other shape it will take if you pinch one end…).
[img]https://plus.google.com/photos/11143...CIuMxdnjhcvbUg[/img]


This is the result.

[img]https://plus.google.com/photos/11143...CIuMxdnjhcvbUg[/img]

[img]https://plus.google.com/photos/11143...CIuMxdnjhcvbUg[/img]



Now, I’m pretty pleased with myself, but I can’t believe I’m the first to attempt this. Yet I’ve found no similar boats on the web, despite many, many hours of searching. Would any fellow forumites be kind or cruel enough to stoke or curb my enthusiasm?

[Paul Pless]

I cut along about a third of the centerline (long axis) and bent it into a « hull » shape

Taking a 'V' shaped cut out of a piece of plywood (or fabric for that matter) then folding it is called a notch. Its long been done in boat building.

[David G]

You're right. You're not the first. But, hey... as far as you knew, it was an original idea. And a good one.

[Rich Jones]

Nice looking little sailboat. How does she handle?
I think the technique is called tortured plywood. It's limited to a few designs. Some catamaran hulls are built like this.
I believe fellow Forumite Wizbang might be doing something similiar with his little powerboat designs.

[Figment]

a.k.a. "dart"

[potomac]

Very nice. You and Wizbang13 have some pretty cool hull shapes there.

[sailorjim]

I think the technique is called tortured plywood. It's limited to a few designs. Some catamaran hulls are built like this.

Thanks for your reply Richard. In fact, I didn't torture the ply, although it tortured me somewhat... Torturing is where you bend the sheet in two dimensions. I just let it take its "natural" form.
As for handling, it's hard to say, cos I've opted for a type of lateen/crabsclaw sail and have only tried it in a F1-2. But it doesn't go backwards

[sailorjim]

a.k.a. "dart"

what Dart is that?

[sailorjim]

You're right. You're not the first. But, hey... as far as you knew, it was an original idea. And a good one.

Thanks David. Have you tried this type of construction yourself?

[Paul356]

The Core Sound boats use a similar approach, although not from one piece.

[sailorjim]

The Core Sound boats use a similar approach, although not from one piece.

Thanks for your reply Paul. From their website, Core Sound appears to use "butterfly" stitch and glue?

[TerryLL]

Standard practice in welded aluminum skiffs. Score, fold, tack. Sounds simple until you try it with a 5' X 20' sheet of 1/4" plate.

[David G]

Thanks David. Have you tried this type of construction yourself?

Nope - I'm not much of a Stitch & Glue guy. I've done a grand total of two boats that way... and am not looking for an excuse to do more - but wouldn't turn away a client who wanted to go that route.

[James McMullen]

My two cents: I've built a kayak and a canoe that way. The problem is its not a very good way to get much initial stability out of your hull form. You are very limited by the limitations of how the wood will bend and curve, and it just doesn't distribute the buoyancy optimally. You end up with a mediocre sectional shape compared to the shapes you can get by developing each panel independently instead of out of a single sheet of origami paper. The only tortured ply hulls that I've seen that actually worked out really well were long, skinny multihull amas, hulls which don't need initial stability because they're multis. Otherwise, you're compromised with your stability curve I think it's an interesting exercise, but ultimately somewhat flawed in practice, which is why you rarely see it. I'm pretty soured these days on designs based on tricksy methods of construction rather than on optimum hull shapes.

[John Meachen]

You can produce a nice boat from a few sheets of ply and they can perform very well.You probably won't be lucky enough to get it absolutely right first time though.Here are a couple of examples,both designs are a bit over 40 years old.

[matoi]

search for
origami frameless metal boatbuilding

[cprinos]

Thanks for your reply Paul. From their website, Core Sound appears to use "butterfly" stitch and glue?

I don't think this would be quite the same effect as cutting a dart and joining the edges because in that case there's still just a single axis to the plywood. On the CS boats, you join the side panels at the bow first, but the bottom and side panels meet in a V shape before unfolding, so the long axis of those panels (the way they bend most easily) is different for each panel. I think I could have stitched it up in 'normal' stitch an glue fashion, but the butterfly technique saved some time. It is a bit awkward with those butterfly 'wings' flopping all over though.

(image on left is from B&B site, on right is mine just after the butterfly was unfolded, but before the rest of the edges were stitched)

[wizbang 13]

I built my first S n G in1978. About the same time Sam Devlin started. The induced compound curve makes for stiffness. James is right about initial stability. I have seen others build boats like this and the bottom was allowed to go where it wanted and the boats were just silly tippy. Thus, the two by four across the middle, with all thread and vice grips.

[wizbang 13]

[Kerry Thomas]

Have a look at Tornado Catamarans.