Wood hulls - to glass or not

I'm building a 15' Phantom sailing dinghy from plans obtained by the designer, and the boat was designed in '71 and was built using sticth and glue construction with fiberglass and polyester resin. I'm using epoxy and glass on my boat however. The plans call for the seams to be reinforced with 4" glass strips, but no glass covering the rest of the hull. Having done some research on stitch and glue, I find that a lot of builders do cover the hull with a layer of glass and epoxy. I'm wondering if I really need the glass cover over the entire hull. I'd like to keep the weight down as much as possible. If I don't use a glass skin over the 6mm ply, what would be a suggested finish technique for a painted hull?

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RE: Wood hulls - to glass or not

I have only one boat under my belt so my experience is limited to my own build. That said, I think it would be OK to limit the use of fiberglass to what the designer's plans call for. I think it might be useful however to give the entire hull a couple coats of epoxy in order to seal the raw wood before painting it. Just my 2 cents.

RE: Wood hulls - to glass or not

If the original design did not call for a glassed hull, you don't need it for structural strength. On the other hand, a light layer of 4 oz glass will protect the wood from abrasion.

I built a dinghy from 6mm okoume for which glass was not specified by the designer. I put a layer of 4 oz inside on the bottom and a later of 6 oz outside on the bottom since those are the areas most likely to be damaged. The rest of the hull is just painted.

For paint, I used the System 3 high-build Yacht Primer and their 2-part linear polyurethane topcoat. The final coat was cross-linked for extra hardness. It worked very well. The Interlux systems sold here also do a good job, but I wish CLCwould start carrying the System 3 paint products.

Good move switching to epoxy, BTW.


RE: Wood hulls - to glass or not

Covering the bottom with glass shouldn't be necessary, and it would certainly add weight -- and expense. It would help some with abrasion, but you'd still want to quickly repair any exposed bare wood.

Finish is personal, and depends mainly on your standards. If you're using all first rate materials then you probably also want expensive paint. But if you're aiming for something utilitarian, people are often happy with porch paint. I'm not kidding.

Cheers, Grant

RE: Wood hulls - to glass or not

I used to have a business building 8 ft dingies, Ply glass,polyester resin.(this was before epoxy resin. I would never ever consider building without glassing the hull with at least 4 oz cloth and a 4 or 6 oz patch down the keel. In the mid 1980 switched to epoxy resin (West systems) and would never ever use polyester again. If you cheap out on your boat that is exactly what your going to get is a cheap boat. Don't wast your time cutting corners, Do it right the first time !!!! Systems 3 2part linear polyurethane is a very good product .!!!

RE: Wood hulls - to glass or not

Thanks for all the great advice! This is my first build and I'm just trying to make sure I don't make any huge mistakes. I think I'll do as the plans call for, and epoxy / tape the seams. I've already done the inside seams. I think the hull will be plenty strong without the outer layer of glass, but I'm going to go ahead and seal the outside with a coat of epoxy. The two part polyurethene is a great reccomendation and I'll go with that as well. I've used it before and had good results with it.

RE: Wood hulls - to glass or not

"I think the hull will be plenty strong without the outer layer of glass, but I'm going to go ahead and seal the outside with a coat of epoxy."

IMO, and that of many, many other experienced builders (but not epoxy suppliers!), you'll just be throwing away your time, money and vast amounts of pointless labor by supposedly "sealing" your your wood with epoxy.

But, if you don't believe that (and many are dedicated to epoxy coating), you should definitely believe that sealing only one side of your wood would accomplish nothing  - except to make for a very expensive primer.

Epoxy is glue. Paint is for painting.

Good luck with your build!

Dave Gentry

RE: Wood hulls - to glass or not

Thanks Dave. As I said, this is my first build, so I'm getting a lot of advice on what to do. I see your point regarding paint vs glue. The plans I have for the boat don't call for sealing with anything. Just tape the seams and paint. I'll do a little more research on this because the epoxy is sure enough an expensive primer.

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