I need a little help

[H-bomb]

Im building a boat out of plywood to test a design could i seal it with caulk?

[hansp77]

Hey H-bomb,
what exactly do you mean by caulk?
There are of course many ways to seal your plywood (is it marine grade?) epoxy being probably the best (and most expensive).
for a test model, I would think you would want to go cheap.

probably the easiest way to seal it would be to use some regular exterior house or decking enamel paint (oil based).
If you don't have some already, then probably someone you know would have an old tin sitting in their shed somewhere, or just buy some (sometimes paint shops have cheap tins where someone has returned something or they have stuffed up the colour).

Thin down your first coat with turps and let it penetrate right in, then once dry apply as many coats as you want. One topcoat would do it.
Pay extra attention to all your edges and end grain, to completely seal it, as this is where the water penetration and damage would be the worst.

What is the design?

[Wynand N]

Simplest way to work with plywood is the "glue & stitch" method. BTW, I'm busy building a prototype 4.5m open daysailer myself using this method.

Check out this link: http://aboatbuildingjournal.com/feb24-03.htm

[H-bomb]

hansp77 it is based of off the higgin design or the landing craft vehicle personnel(LCVP)

[timgoz]

H,

The store I worked at would sell all gallons of paint with a screwed up custom tint for $5.00 US each. When you consider that decent exterior oil starts around $25 a gallon, thats a good savings.

If your price is a concern, get all of the same type, they will each be an individual color. You might luck out and get several the same. Mix it all together for a consistent tint. This assumes that appearance is not a concern. The store may be able to place it all in one 5 gallon bucket and shake it mechanically. It is real critical to mix oil-based thoroughly.

How large is this landing craft?

Take care.

TGoz

[H-bomb]

Its 8ft long 4ft wide and the sides are 2 and a half feet high

[timgoz]

H,

For one complete coat of paint, inside & out (excluding seats or any decking) on this hull you have approx. 184sq feet. Check the paint can for expected coverage and your good to go.

Sounds like a cool project. Are you going to couple the two electric motors together to steer or mount them rigidly forward and place a rudder between them? If the former you would probably have a lot more manuverability, but it would be more complicated. KISS (Keep It Simple) has alot going for it, and this approach would favor the later option.

Take care.

TGoz

[bilbo]

Plywood is an effective boat-building material and is relatively long-lived - provided its surfaces and edges are sealed to prevent the rapid absorption of water.

'Flow coating' ( see Gougeons' book ) in epoxy resin is well-regarded, but relatively expensive. Perhaps next best is polyester resin. Both these materials act as bonding and sealing agents.

You get a very strong and light skin structure where you fasten together two or more layers of thin plywood strips, laid at cross-angles to each other, where each layer is 'flow-coated' in a resin product and effectively glued together. These layers can effectively be mechanically fastened, and bonding pressure applied while the 'glue' goes off, by liberal use of staples set by a staple gun. For temporary duty, ordinary ( rusting ) steel staples will suffice. For permanent duty, staple through a 4" strip of packing tape and pull/remove after the glue has set - or use Monel staples. These are not cheap, but do not corrode in place, so can be left in - saving $100s in 'making good' the surface....