Fiberglass on a wood Hull

[O'City Fisherman]

So my father in law gave a a 18' Cuddy Cabin and it needs work. I was thinking after sanding the outside hull of laying fiberglass over it before painting for added support?

Has anyone out there done or seen anyone do this before?

If so then how did it work? [img]images/icons/confused.gif[/img]

[Phish_on]

My boat is fiberglass-over-plywood, I've done a couple of significant repairs. When I was a kid, I "helped" my dad put fiberglass over our 14' wood boat.

You're looking at a huge amount of sanding. For good results you want to get down to bare wood. You might want to start with paint stripper, which is more unpleasant than sanding but a lot more effective.

Applying the fiber cloth is almost delightful after all the prep work.
Then of course you have to sand between layers - I'd go for at least two as long as you're doing it - and then sand before painting to kill the gloss on the resin.

Give yourself about a year [img]images/icons/cool.gif[/img]

[Hoosier Daddy]

If the boat is plywood now, I would definitely put some kind of glass down if you plan on keeping it for awhile. Most all plywood boats came glassed originally anyway. Planked boats are another story -- if its planked I wouldn't try to glass it, thought people do. If its a nice boat (ie worth spending some bucks on) you might look into using West System epoxy sheathing. Its basically fiberglass, but is supposed to be a little better and a higher quality job when you are done. You also hear wooden boat folks talk about "cold molding", which may be the same thing. There are some good books on the stuff, check Powell's for the older stuff. You can also pick up a copy of "Wooden Boat" magazine. Freddies usually has it. Sometimes they have articles on this stuff, but lately just ads for coatings, epoxies, etc. Might be a place to start. I know West System sells a test kit of their materials for around 30$ that gives you an idea of how it works and what it would take to do the job, and some of their products are available at Fishermans Marine. If you do this, I would look around for the fiberglass, Fisherman's seems a little high on their prices for the stuff. My Dad, Uncle, and I did a plywood runabout restoration about 10 years ago. We sanded it all down, replaced some wood, and glassed it over with standard fiberglass and cloth, kind of like Phish is describing. It ain't a whole lot of fun, but its not too bad. He's right, the prep part is the worst, and the most important. It all kind of depends on what you use. Some fiberglass resins produce what they call an "amine blush", which I guess is chemicals evaporating from the resin as it dries. Anyway, on these resins you HAVE to wash the hull down with soap and water between resin coats to remove this blush or the next coat won't bond properly. Also, I believe some of the better (read "MORE EXPENSIVE") epoxy resins don't require sanding between coats if done within a certain time period. Regular glass does require sanding between them. I would probably do it anyway, because it turns out much nicer, but might save you time if that's important. Anyway, we did the cloth, glass, sand, glass, sand, glass, sand thing, then topped it with some body filler where necessary and sandable primer (Dad was an autobody man), and block sanded it just like you would a car, afterwards it was smooth as "glass", and when the paint went down it looked really great. I don't know how that old boat has held up, but since we pretty much built her back from scratch, I'm sure it probably is still solid. Although, since my Uncle ain't the most energetic guy, it probably looks like it hasn't been kept up.

[WaterDog]

I used west systems epoxy on an old wood sled I had a few years back. Worked great! You will need to get to the bare wood for best results.

Here is how it turned out: http://www.sites.onlinemac.com/rspof...oody_page1.htm

Good luck!

[Hoosier Daddy]

Waterdog -- I checked out your site awhile ago. The boat turned out real nice. I would love to take on a project like that eventually, or even build from scratch. If I ever get the time or money to do it [img]images/icons/rolleyes.gif[/img] . I have to ask for future reference : have you bounced it off any rocks? Did it break your heart? Or was all well afterwards? I would like to think I can do something like that down the road, but I'm afraid I would be too paranoid to actually use the thing after I got done. Do the two layers of glass adequately protect the wood? I would love to believe that a wood boat can be every bit as durable as aluminum on a river, please tell me its so!!! I have some ideas that depend on it being true!!!!!

[Roeboat]

A couple of hints:
1. Buy a "hard pad" for your circular sander, and a tube of feathering disc adhesive to adhere the sandpaper. The hard pad will cut well (not as fast as a grind pad, but much more forgiving while learning.
2. Resin has no strength to speak of. The strength comes from the fiberglass cloth. The more cloth the stronger. Buy in bulk. Resin and cloth are much cheaper in quantity.
3. If you are glassing tricky compound curve areas or even upside down, here is a good trick. Squeegee a thin layer of "Hot"(lots of catalyst) laminating resin on first and let it dry sticky hard. Now smooth on the cloth to the resin making sure there are no wrinkles. Wait til the cloth is adhered semi firmly, and now glass it.
4. Sanding resin must now be applied over the glass. Make your own! Commercial surfacing agents are poor at best, meaning they sand very poorly and eat up lots of sandpaper. Grate about 1/4 stick of parafin wax into a pint of styrene. Put out in the sun or heat in a double burner setup til the wax dissolves. Add some of this solution to your lam. resin for a very sweet sand session. And sand while the resin is "green", in other words soon. If you wait a day or two the resin will be much harder to sand.
5. Epoxy resins are always very toxic. Use extreme care with them. They are thick and laminate poorly, requiring extra time for saturation. They are heavy and expensive relative to polyester. They sand easily on the plus side...
6. For impact resistance on a boat give me polyester resin with lots of glass hand layed tightly. Most and I mean about all fiberglass boats use chopper guns to spray mat/resin which is very weak. If you want strength you will have to bite the bullet and spend for lots of cloth and then laminate it tightly by hand with a squeegee and roller.
7. for boats, always use at least two layers for anything...say 2 layers of 8oz. for the sides, etc. That way you will avoid cracks later on from poor sanding, wood movement, etc. I have about 90 ounces of cloth on the bottom of my boats and up one foot on sides. That is about perfect to avoid rock damage.

Thoughts: I glassed the inside of by driftboat with epoxy and have regretted it ever since. If I had it to do again I'd have used polyester there also as it is much more rugged for hard use(rocks, etc.). My drift boat (glass/wood, with no frames or stringers)has bounced happily downstream for years without me making any repairs to the bottom at all. With a finished weight of 180 pounds (without anchor/gear) it is exceptionally light and strong. Fiberglassing takes time and a willingness to get "dirty" but it can be very effective when done well.

[WaterDog]

Chnookie,

I never truly tested the rock bouncing ability. As stated above the more glass cloth the better. I will say that after I finished I wasn’t too worried about poking a hole in it since I knew how to fix it. [img]images/icons/rolleyes.gif[/img] I pretty much treated it as a aluminum boat. I was never afraid to beach it. It had some gouges in it but it never bothered me. Heck, I got gouges in my new boat already! Seemed to be tough as nails as far as I could tell. Mine was built with a 1/2 inch or 5/8” bottom with cedar 2x4 ribs on 16” centers. I was not afraid to take it on any river.

If your thinking about taking on a project like this make sure you don’t rush it and allow LOTS of time! The hours you’ll spend is incredible. Good thing I was between jobs during that project.

I would not epoxy the inside either. I would just use a quality stain and do it every year or so. It’s wood and therefore it needs more care and you really need to store it inside or under cover. You’ll turn a lot of heads with a nice woody. [img]images/icons/shocked.gif[/img] [img]images/icons/grin.gif[/img] Hope this helps. [img]images/icons/cool.gif[/img]

[Roeboat]

Hey Waterdog, your boat sounds beautiful. My driftboat was built with a different concept. It is only 1/4 inch thick ply with no frames. The sides are wired together and glassed. All the strength comes from fiberglass and the bottom flexes over big rocks. The inside is left natural but the outside is green pigment/glass. When I first launched the boat it weighed 130 lbs. but after a nasty low water river float, I added 50 additional lbs. of resin/glass and it is a very tough craft now. I can literally bounce it down a rip rap concrete bank to the river. While the outside requires no maikntenance the inside does. And the idea of using a high quality spar varnish and keeping it covered are both good ideas. Good luck with your projects. Building boats is work, but lots of fun also. And if you build it, you know how to fix it.