Fastener spacing in plywood skin ?

[les45]

I'm fast approaching the time to skin my weekender. I plan to use 3/8" plywood glued and screwed. I will have lots of screws around the edges of each panel, but how often should I screw out in the center. I want to keep the hole patching in the center to a minimum.
Spar spacing is 12" or less (on edge) and I will glue the entire length of each spar and around all edges. The final finish will consist of fiberglassing of all joints and breaks, CPES primer throughout, and a West system boat paint.

[linuxmanxxx]

Glue is stronger than wood so why go to all the trouble of using screws? Just get a finish nailer and glue and shoot the plywood in place and when it dries it is stronger than the wood and very little finishing needed to move on to your next step.

[aggie79]

I used screws as temporary fasteners. Spacing was about 3" on center. I did use scrap 1/4" plywood to help spread out the pressure.

[rowerwet]

my whole td is fastener-less since the whole box is glued at every joint and every joint is put together in a method known in boat building as the inside chine log method, every join of panels has a wood block running inside the inner corner, glued to both panels. In theory my TD should be able to float on it's roof.
If you are using a quality glue, why bother with screws, except to anchor everything until the glue dries.

[eamarquardt]

............ In theory my TD should be able to float on it's roof...................

OK, I'll bite. When is the maiden voyage?

Do you plan to rig it as a sloop, ketch, yawl, cutter, ????

Cheers,

Gus

[Forrest747]

Delted

[Forrest747]

Forget the middle ones keep them at the edges and if your fiberglassing your edges that will make it very strong. one every 12 inches along the edges should be fine. Still put the glue in the middle but using Toms method of using 1/4 inch to spread out the screw force is a good idea and helps preventing dimpling of the screw heads.

[rowerwet]

............ In theory my TD should be able to float on it's roof...................

OK, I'll bite. When is the maiden voyage?

Do you plan to rig it as a sloop, ketch, yawl, cutter, ????

Cheers,

Gus

it is only a theory, though I have built three boats using the same method of construction. (one using epoxy and glass) getting storm warning off the trailer, rolled over onto the roof, launched, wouldn't be fun, and then I think it would take a rather heavy keel to keep it inverted, most likely to heavy for the limited free board caused by the doors being only 5" or so from the roof. I do figure I could sail it much like float plane pilots learn to, using the doors...
I still very much want to figure out how to attach two 17' canoes and take it boating for real. much like that thread about extra receiver tubes on the frame...