Large hole in fiberglass hull. Need to repair.

[Brasshopper]

I appreciate all the advice. The West Marine book recommends epoxy for a repair this large because they say that a polyester repair will shrink. They say that the they have a hardener that won't shed the stuff that peels off the gelcoat. It is the same hardener you would use when you coat wood to prime it for finishing.

Thoughts? If I knew that polyester would not shrink, that would be my choice.

They claim that you can just wash epoxy to remove the stuff that peels the gelcoat, but after listening to the experience here, I don't believe that. But if the special hardener simply does not produce it, well, I don't know. What about the claim that polyester will shrink?

I can see that the crack goes farther than I initially thought. Right now the boat is on 4x4 cribbing, two stacks at the stern, one at the bow. Bit by bit I am cutting the old trailer out from under it. I need to put the new trailer under it once I get the bunks fixed up. Once I do that I will be able to go inside it and assess any hidden damage. I am worried about going on the boat while it is on blocks.

I bought the boat and trailer for $1000. The kicker outboard cost me $650. Prop needed a rehub, $36.

Replacing the trailer cost $400.

To redo the standing rigging with quick releases for the forestays will cost $200 (so that the mast can be raised and lowered in under an hour). I will also need to build a gin pole, etc. There are ideas for stabilizing it as well.

The wood to replace the bowsprit cost $130. I am going to make a lamination, hard outside, soft core.

I will get a local estimate for the fiberglass repair, but over a grand for a repair breaks the budget.

I know I want to look at the electrical system, probably will need dual 12 volt deep discharge batteries with an isolator. Eventually. I want to put a homebrew autopilot on it eventually. I believe I can build one for about $150, linear actuator with position feedback, arduino board and flux gate compass, pushbuttons and LEDs. OK, maybe $175. But that is for the future. And I probably need to replace the old radio, I want to put a GPS/depth finder on it. The depth finder on it now is kaput.

And, yes, I know it will cost me more than I think it will. It always does.

[boatpoker]

Originally Posted by Brasshopper

The West Marine book recommends epoxy for a repair this large because they say that a polyester repair will shrink. They say that the they have a hardener that won't shed the stuff that peels off the gelcoat.

The West book gives good advice. The "stuff" you are talking about is an "amine blush" which is a chemical that rises to the surface in many epoxies and can cause gelcoat or any other adhesion issues if not removed. There are amine free epoxies as West advised. Even so, a two part epoxy primer is advised before adding any other coating. Polyester does shrink and that shrinkage over a larger area can cause disbondment of new from old particularly as the bond of polyester is trictly mechanical while the epoxy bond will be mechanical and chemical ..... i.e. much stronger.

As I said before, if my 13yr. old son can do it so can you or any other reasonably intelligent person. I have have had my 10yr. old grand daughter do epoxy work on my boat. My wife is building a new cockpit deck with epoxy right now. It ain't rocket surgery, pay attention to the West book and do it.

[hellosailor]

Go to your local automotive body supply store. They sell gallon bottles of "3M Prepsolve" and similar solvent mixtures that are designed to remove waxes, polishes, silicones, amine blushes, all sorts of things that can ruin the bond to the next layer, whether that's gelcoat or paint. In the overall scheme of things the cost will be trivial, and you'll know that you've got a professionally compounded cleaning solvent, instead of just stuff from the hardware store that might or might not work as well for almost the same price.


Use it with lots of clean white terry rags, or Bounty brand paper towels, which are damned good at absorbing whatever crud may be on the surfaces. I prefer the paper towels, I'd rather throw them away than wash them.

[HappyMdRSailor]

Originally Posted by Brasshopper

I can see that the crack goes farther than I initially thought.

Right now the boat is on 4x4 cribbing, two stacks at the stern, one at the bow.

The crack and required cutting/grinding out is sure to enlarge at least one or two more times! Just make sure you get that bad glass out...

Get some stout ground stakes like 1" rod or something, drive 'em in deep and ratchet tie down the boat... It will be sturdy as all heck, and the trailer won't get in the way of your repair and hull work...

[Cheechako]

The reality is you should sand epoxy even if you are putting epoxy over it. (unless you do a hot bond while it's still tacky) Using chemicals to remove the blush is possible but I wouldn't trust it 100%. Just me.
The other reality is yards have been using laminating resin for repairs for decades to no ill effect. Just do whatever suits you.
One 10 ft long repair on the side of one of my boats was done in 1993 with normal resin. It passed survey and looked fine/unnoticeable 2 years ago when a third owner since me bought it.

[hellosailor]

From 3M and other good sources: Always solvent clean before sanding! If there are any contaminants on the surface, the sanding will simply "engrave" them into the new material, making it virtually impossible to get them out, and permanently weakening the bond.


FWIW.


A lot of people solvent clean both before and after sanding, just to make Real Damn Sure they won't have one more reason to do the whole job all over again. Solvent is still cheap.