Repair consult for curvy portions of hull?

[feralcomprehension]

Hi all,

First post.... I got a cheap Sunfish ('71?) a month or so ago and am working thru its issues. The cockpit floor was badly cracked and then horribly repaired, but that repair, though large, should be relatively straightforward. I could use a little advice on damage to some curvy parts though. Can anyone comment on how best to address glass repair in the areas shown below?

Here's the aft end of the keel. Looks like it was dropped. Even though there seems to be some internal splitting there's no trauma visible on the outside save for the obvious (which I've already ground away).

There's crush damage at one aft upper corner as well. I pulled the trim off and ground out (most of?) the dead glass:

The repair videos I've watched (no experience with this stuff, but pretty handy in general) generally describe repairs to nice big flat areas, with or without access to the back. What do I do with these injuries? It's not in this year's budget to convert to the later rudder style, so cutting out and replacing a big part of the transom isn't particularly appealing.

FWIW my intent is to use West Systems epoxy and some modified twill glass as it's supposed to be more conformable, but at this point I haven't bought supplies so if I need something else, I'd be pleased to hear it.

Thanks in advance for any tips!
Robert
Ferndale, MI

 

[L&VW]

A retired buddy uses West epoxy around boats almost every day, so you're off to a good start. His instructions are copied (in blue), and appear here:

Hull Repair | SailingForums.com

But in short, sand out the damage to 6" away from the hole, leaving the area around the hole paper thin. Build up layers of bi-axial cloth in increasing / decreasing size—preferably in one "go". Allow yourself time for cutting and daubing by using a slow-setting catalyst.

 

[fhhuber]

Possibly get some foam similar to the core of posterboard (water removes the paper) to insert behind the fiberglass patch and support the fiberglass so it doesn't sag when doing the larger holes. You may or may not need inspection ports for installation of the support material.

This isn't for added strength. This is for controlling the shape of the patch material. Glue the patch support material in... let that cure, sand a bit if needed to allow for curvature and then do the fiberglass work

 

[feralcomprehension]

Thanks for the input! I've already sourced and cut holes for a pair of inspection ports (a 6" clear ahead of the bridle mount and a 5" between the mast and the spray guard) and do intend to back up the repairs as best I'm able (I'll use batten-like sections of fiberglass strip for the cockpit floor gash) but this: "...sand out the damage to 6" away from the hole..." is one of the things I'm most perplexed about, especially for the keel/transom repair.

How to sand into the groove for the rudder plate bolt, and will I be able to get wet-out glass to conform to that curve?

 

[fhhuber]

You can get the wet fiberglass cloth (up to 2 oz/sq ft) to conform to just about anything.

To sand in tight places you glue sandpaper to shaped blocks.

Note: I like to apply my fiberglass layers: Heavy weave smallest area, moving to larger area and lighter weaves as I get closer to the outside surface.

Maybe even a thick mat first, aiming for 1/2 oz as the final layer. 1/2 oz cloth is very fine weave and if you plan the patches of fabric right you may need very little filling and sanding before paint or gel coat.

 

[L&VW]

but this: "...sand out the damage to 6" away from the hole..." is one of the things I'm most perplexed about, especially for the keel/transom repair.

The repair will be stronger than the hull material, so tapering-out that large area will keep the patch from breaking out during any future misadventure. Your grinder will work fine; just remember to taper the repair gradually down to the hole.

Use a roller to remove bubbles. Plastic rollers are relatively inexpensive, but are "one-use only". Locate a metal roller and, using a propane torch, burn off the resin after each use.

How to sand into the groove for the rudder plate bolt, and will I be able to get wet-out glass to conform to that curve?

You've explained that you've "got a budget". Your budget might not stand the strain, but now would be a good time to update to the later rudder gudgeon—saving your efforts in the groove area. Personally, since the repair wouldn't be visible, I'd build it up with epoxy to make the gudgeon area bulletproof.

There are folks here on the forum who have acquired "organ-donor" Sunfish. They should be able to get you a good price on used parts. Use the "Inbox" feature here (above, right corner) to exchange information.