Hull patchwork repair

[AP0196]

Since it was a thru hull, do you have access to the outside? How does it look out there? Really the best way to do something like this below the water line is to do it from both sides. And people are right -- it's not a hard or time consuming job really. Think of it like painting. It's mostly prep. The painting part goes pretty quick. I'm going to assume (I know, I know) that you're just going deal with the issue inside of the boat, and not do both sides.

You'll need to grind out what's there and back into solid material. I think the ratio is 12:1 or so. You'll have to go back a bit into solid material to get that kind of a taper. As people have said -- prep work will save you from having to wipe down all the surfaces (think about it like sanding drywall, it gets everywhere). A shop vac right next to the grinder / sander (or one with built-in dust collection -- I have a nice Bosch) will help a lot. This is the time consuming part. The rest is hurry up and wait.

Once you've got the area ground down, clean everything. Acetone works in a pinch, Total Boat surface prep is my go-to. Cut some fiberglass circles starting with a small one to cover the hole plus a little bit and increasing the size to the edge of the patch. Depending on what fiberglass thickness you use, you'll need a bunch of pieces. I did it on a Catalina 22 and only had 6oz cloth handy, so I used like 10 - 12 pieces. With something like 1708, you won't need that many (but probably more than you think).

Grab a sheet of plastic (lay a garbage bag flat) and apply some epoxy to the smallest patch then to the hull. Put the fiberglass patch over the hole and smooth it out with a disposable paint brush as best you can. Repeat with the remaining chunks of fiber glass.

Let the epoxy setup, and sand / fair if you want (again Total Boat 2-part epoxy fairing compound) sand again, repeat as needed until it's perfect. Or, until you decide it's good enough. Slap some paint on it and call it done.

The hardest part is the prep and grinding. The epoxy part is a 30 min job and then you wait for it to cure.

Thanks for the detailed response. Yes since the outside is smooth and sounds solid, idk if there’s a better way to test, I’d like to leave it alone if possible. All I really want to for water to not leak into the boat. Right now im not even sure the patch even leaks, but I’d like to repatch it just to be safe.

 

[Foswick]

I mean ... you can just rough up the inside and slap several layers of glass over the area. That would provide a margin of safety over the existing patch. But ... you don't know what you are patching over. There are three areas of concern:

• Voids: Any small air pockets weaken the existing repair - at best. At worst, they invite other secondary problems that could spread to weaken the surrounding area. So, to properly repair this - even for a "good enough" repair, you really should grind away material that helps create a void. That is, any area that is not completely solid glass/epoxy should be removed.
• Weak bonds: Even for areas that do not contain voids, the existing patch suggests that not all of the layers of the repair are completely bonded to the underlying structure and/or each other. If you do not remove any poorly or incompletely bonded layers, you cannot trust the area. It might outlast the boat, but it might fail.
• Lack of barrier coat: Even if all of the above is fine, you don't know how the exterior was treated. So, you don't know how protected it is against osmotic intrusion.

In short, you could probably shortcut the repair and be just fine. But, you won't know until you know. It might be a situation of do it now or do it again later.

 

[dlochner]

Would the job be possible with a rotary buffer and sanding disc? Would wet sanding cut down on airborne debris or would that just create a mess I’d have to wipe up?

For a small area a rotary disc sander like this one from Amazon would work. Use very aggressive paper, 36 or 40 grit and connect it to a shop vac to reduce the dust. Lately I've been using sanding mesh instead of paper. It seems to last longer and is less prone to clogs.

Wet sanding is the last step on the visible surfaces to get a smooth finish.

If it's that poorly done on the inside, who knows what kind of work was done on the outside

This. Open it up to see what you have. I wouldn't trust it unless I removed all of the old repair.

The good news about fiberglass repair is sandpaper fixes all errors. If you screw it up, get out the sander or grinder and try again.

 

[Mitch Witt]

How far do I grind it down?

You must become familiar with "scarfing" to understand how grinding is done. Consult West System website or other resources on small Fbg repairs. Haul the boat for this repair. Laminate must be dry and free of oils and contaminants.

 

[AP0196]

I hear all of your responses and I appreciate all the advice, but I’m not cutting off an arm because a finger is bleeding. If the arm gets infected, I’ll address it then. I’ll keep you updated.