Is this necessary?

My first post... Tried searching thru the posts in this forum but I still have doubts so heregoes:

Im planning to build a wooden 17' cruiser, planing hull with a 25hp outboard. The plan (circa 60's) specified white oak as frame. I live in the Philippines and white oak is not available here so I intend to build the frame out of Philippine mahogany (red lauan) which is lighter than white oak but relatively weaker. Marine plywood will be used for the bottom and sides. The boat is intended to cross the islands so I would be spending hours without a shore in sight.

I need some "assurance for the hull so I intend to fiberglass it (polylite?) and epoxy. The order of material will be as follows:

1. bare wood (lauan and plywood)
2. cover the wood with fiberglass (as additional strength)
3. cover the fiberglass with marine epoxy paint
4. Paint with marine grade urethane (or acrylic?)
5. Top coat for aesthetic reasons

My questions are:
1. Is this necessary? Or will I achieve the same benefit by painting the wood with epoxy only (and not the fiberglass) and then paint it to protect from UV rays?
2. Would the epoxy bond to the fiberglass?

 

To use the luan instead of the White Oak you will need to make the internal structure (ribs ect) a bit thicker.

I would cover the boat with cloth (not CS mat) and use epoxy resin , as it holds onto the wood better than any other.
Then simply paint with normal marine paint for "looks" and bottom protection from growth.

FAST FRED

 

thanks for the fast reply fast fred...

1. so the next question would be how much thicker? say double perhaps? (from 3/4" white oak framing to 1 1/2" lauan)

2. i cannot picture out how to use "cloth" with epoxy resin... i can only imagine fiberglassing (lay out the fibermat then brush with polysterene)... can someone pls enlighten me or give me an overview on how this procedure works?

thanks a lot...

 

more tips

Here are some more tips to add to Fast Freds post. Radius all edges so that the glass clothe will wrap around without forming a bubble. Fillet all inside corners so that the glass will wrap without forming a bubble. Seal all plywood edges w/ epoxy. I can't stress the importance of this enough. Use epoxy formulated for warm climates. Precoat all plywood with epoxy. Any place you cut a hole in the plywood seal the endgrain w/ epoxy.

 

clothe w/ epoxy

The clothe Fast Fred mentioned is simply clothe made of glass fiber just like the fibermat you mentioned. Wet out the the plywood with the epoxy with a roller. Lay out the glass clothe and wet it out w/ the roller. Use a plastic squeegie (plastic blade) to remove excess epoxy (scrape it off) and a grooved rolller to roll bubbles out from under the clothe. You want it to be not shiney and be able to see the texture of the clothe.

 

If you can get it, xynole polyester on the outside will be better as a sheathing. It will drink more epoxy to fill, but it will be substantially more abrasion-resistant than fiberglass.

I am coming to the conclusion that a thin layer of fiberglass set in epoxy on the grounds of strength and abrasion resistance is mostly a feel-good step with no appreciable benefit given the cost and work, especially in light of the super hard paints available now.

good luck