strip plank technique

Hello all
I need advice on the importance of scarfing the strip planks for the 26 foot newfoundland skiff that I am building. I plan to epoxy inside and out 3 coats and have 10 oz cloth on the hull. Can I get away with not scarfing the planks and butt joining them on the temp. frame.
thanks
richard

 

I have, but it is probably only possible or wise if you are using a good gap-filling adhesive. My boat is a 24 foot lobster type, with atlantic white cedar 8 foot strips (3/4" thick, 1.25" wide), glued with PL Premium, and screwed as much as possible with 3" epoxy coated screws. I am following Dave Gerr's scantlings, and using Sam Devlin's approach to integrating the boat's "furniture" (bulkheads, bunks, seats, compartment divisions etc. etc.) into the structure by gluing everything to everything else.

With each butt, I clamp it very hard between metal angle pieces and sheet plastic release material, so the glue is essentially compressed into the butt join. I stagger the butts, obviously.

Since my local cedar is so light, soft and forgiving, there seems no reason to bother with scarfs, when butts are so strong and backed up by solid planks on either side. The glued joints are much stronger than the wood, and my own tests confirm that the glue is completely waterproof. It should, none the less, be properly coated with epoxy anyway.

Like you, I am going to epoxy and fibreglass on the outside, and ditto the bilges inside.

Tony.

 

What's the point?? Scarfs are not that hard to cut...

 

Agreed. But if you don't have any good reason to cut 300-400 or so un-necessary scarfs for a 24 footer, why do it when the alternative is entirely adequate?

Tony.

 

300-400 butt blocks
Chandler

 

No butt blocks used when strip building.
The adjacent strips serve as adequate reinforcement.
Tony.

 

i did see an article in WoodenBoat a few issues back
i believe it was the december 2003 issue
the article discussed scarfing plywood joints
and had some photos and/or diagrams
for setting up a jig that could possibly help you
especially with 300-400 joints
a production method and tool set up may be one answer
that would make your project less daunting

~poetprince

 

Thanks PP, but I don't have any problems! The boat is planked now, and I am at the fairing and epoxying stage. If I had thought that scarfing was necessary, I would have done it (I agree, it is easy enough with a simple jig). The point is, I think, that simple butt joins in strip planks are fully adequate for this particular boat (only 24 feet, rather light conditions of service [displacement speed on inland river and lakes], and pretty soft and weak wood). The scantlings are "respectable" (i.e. I havn't just invented them), see Gerr, "Strength of Boats" for details and reasoning.

Change any of the use parameters, and I can easily imagine that a resulting scantling change might imply a need to scarf plank joins, amongst other things.

Regards, Tony.