Bottom exposed!!

runner · #1 (**permalink**) 09-13-2008

This is the bottom of the aluminum dinghy I bought. Everything has been sanded and wire wheeled from the top of the chine rails down.

I need to seal the keel that has old decayed crud trapped under it. I need to fill the pits to fair the hull. I want a bottom safe to drag up on a gravel bar so I want at least a hard coating. I am thinking about a coat of Gluvit on the keel and badly pitted areas first. Then sanding that down and putting over lapping thin sheets of glass or carbon fiber so that they both overlap the keel and extend out to cover the bottom to the chine rails. Epoxying that down with another coat of Gluvit. Adding about a 15inch strip of cloth over the keel from end to end and epoxying that down with Gluvit. Sanding then applying a third coat of gluvit. Epoxy paint over that.
Will that fix my problems and be strong enough for use on a boat that will get nosed into the bank or gravel bar a lot? Should it have wooden keel and chine strips added for added protection? Is that too heavy of an answer if I use fiberglass?
Thanks in advance for any help given!

jaschrumpf · #2 (**permalink**) 09-13-2008

Is it just me, or is doing all this work on an aluminum boat gilding the lily?

When I was in Boy Scouts we used those aluminum Grumman canoes for the very reason that, being made of metal, you could drag them over rocks and such without worrying about putting holes in them. I really don't understand why you'd want to cover a tough aluminium bottom with all those layers of softer material.

If you want it to look nicer, why not just get some metallic aluminum paint and put a couple of coats on it?

I speak under correction, of course. I may be missing an important point here, but I don't understand glassing over metal as a concept.

Freesail99 · #3 (**permalink**) 09-13-2008

Do you use the boat in fresh water ?

sailingdog · #4 (**permalink**) 09-13-2008

Glassing over metal can be problematic, since the metal generally expands and contract more than the fiberglass can... and it will lead to the two separating.

SVDistantStar · #5 (**permalink**) 09-13-2008

Check out Gflex epoxy from west systems, its made for use on metal boats. Ive used it to do some repairs on my jonboat and havent had any issues with it.

sailingdog · #6 (**permalink**) 09-13-2008

SVDS-

He's not talking about doing repairs...he's talking about coating the entire bottom of the boat by the sounds of it.

Quote:

I am thinking about a coat of Gluvit on the keel and badly pitted areas first. Then sanding that down and putting over lapping thin sheets of glass or carbon fiber so that they both overlap the keel and extend out to cover the bottom to the chine rails. Epoxying that down with another coat of Gluvit. Adding about a 15inch strip of cloth over the keel from end to end and epoxying that down with Gluvit. Sanding then applying a third coat of gluvit. Epoxy paint over that.

BluewaterBruce · #7 (**permalink**) 09-13-2008

Sand blasting is best for metal of it is to be covered, Bar-Rust is a great metal sealer - they use it on oilrigs in the Gulf. The Bar-Rust can be sanded as well creating a more ascetic looking dingy - if you do not stop to sand you can apply all layers without sanding including a hard bottom if you do them all in the same day. It will still look beat-up if you drag it on the rocks but most often, the fish don't mind.

sailingdog · #8 (**permalink**) 09-13-2008

Bruce-

I don't know how much use Bar-Rust is going to be on an aluminum hull. Sounds like something more designed for steel hulls.

runner · #9 (**permalink**) 09-13-2008

The reason is I don't want it to sink. The hull has two pits all the way thru and the keel leaks like a sieve. It has to be sealed or it is a pretty flower pot! Short of having it welded, sealing the keel and then glassing from chine to chine was the best way to put an end to the leaks, add support the the keel that has saltwater corrosion under it, and to fair out the better than eighth inch pits on the bottom. I could drill the keel and inject epoxy into it and then just fair the bottom in some way.
Not doing this for something to do. The old boat has to be repaired, and i just want to repair it right.

Yes I am going to use the boat in fresh water.

The Gluvit is supposed to be self etching for use on aluminum. It makes some pretty strong claims, but when I asked people here that had used it, all the responses were positive.

If I was set on the best way to proceed, I would not have asked. I did not ask if I should proceed, but instead, the best way to proceed. I don't think I will have it sand blasted, but I may use one of the aluminum cleaning products before the first coat of epoxy. If someone else knows of a better way to repair and support the keel on this boat, please let me know. The way I have planned is right at 200$ and a lot of time to do it right. That is before paint. Believe me, I am open to suggestions!

ws6fiero · #10 (**permalink**) 09-15-2008

Mobile home roof (cool) seal it & call it good...