Anchor Locker Fiberglass Repair – Boston Whaler 13 Restoration – Part 3

One aspect of this Whaler 13 restoration that I’ve been anticipating is repairing the large hole in the anchor locker. This is a medium to large endeavor in fiberglass repair. I’ll be using epoxy resin to lay down the fiberglass mats. I’ve also already used “excess” epoxy resin from other repairs to create a solid epoxy bed underneath the fiberglass repair I’ll be laying in. This is not really part of a fiberglass repair, but in this case, it adds a substantial base to the repair. Any future anchors bouncing in this locker shouldn’t cause any serious damage!

Fiberglass Repair – Cutting Out the Soft Spots

The first thing I did was to mark of the surrounding areas that are weak. Pressing on the fiberglass in these areas revealed weak fiberglass or missing foam underneath. I carefully marked the these areas. After that, I drew a perimeter around the weak areas. The next step I took was to cut away the areas with an oscillating multi tool. Next, I sanded the entire area where the Fiberglass patching would be applied.

Cutting Away Bad Fiberglass
Sanding Anchor Locker Fiberglass Repair

Filling In the Gaps with Expanding Foam

Once I had all of the weak areas cut away, it was time to add some expanding foam. I used the stuff they sell at the Home Improvement stores to insulate cracks and openings. Whatever you do, wear gloves, this stuff is like super glue when uncured. I lay down a layer of this over the opening I created when cutting away the fiberglass. I let this sit overnight so that it would have a chance to cure.

Once the foam is cured, it’s time to cutaway the excess and shape. And there was excess! The stuff expanded to several times its original volume! I used the multi tool to cut all the excess away and then rough shaped it with the sander. After that, I sanded the entire surface where the fiberglass mats would contact and a bit beyond.

Prepping the Fiberglass Repair Mats

First Cut Out the Mats

I am using several thicknesses of fiberglass to fix this hole. My plan was to use two layers of woven fiberglass cloth as a base. After that, two layer of 1.5 oz chopped strand and finally two layers of .39 oz chopped strand. To get this fiberglass repair done, I used a slow setting epoxy resin rather than polyester resin. Less smell, and I find it easier to work with. Interestingly enough, I am using epoxies for the entire boat restoration.

Before doing anything else, I cut all of the fiberglass mats I would need. I started with the smallest first, this one would overlap the hole by about an inch and a half on either side. So I measured the hole (accounting for the curve as well). I added three inches to that measurement and cut the first piece of fiberglass cloth. 

Authors Note

Although I cut these mats to fit a tight space, the best practice is to tear the fiberglass around the edges. Tearing will give it more of a tapered surface to blend in with the existing fiberglass.

After that, I added three inches to each successive layer and cut them. As I cut them, I lay them down in reverse order. So the first mat to be put down is at the bottom of the pile. When I am ready to lay down the fiberglass repair and resin, I’ll flip the pile over. That will insure they are in the correct order to lay down.

Fiberglass Mats in Ascending Size Order

Getting Ready to Patch the Hole

Now that I’m ready to start laying down the fiberglass. I want to make sure I have all the tools on hand that I’ll need for this. One of the key tools I’ll use for this is a finned fiberglass roller. I’ll be using a small one since this is a fairly confined space. Of course I’ll also use a chip brush and mixing paddle as well as a small mixing container for the resin. Last but not least, the slow setting epoxy resin and hardener. I used the 5:1 epoxy from Total Boat. One pump from each container gives you the right proportions of resin to hardener.

Before starting, I wiped the entire area down with acetone. You want to make sure the surface is squeaky clean to give the resin a good base to adhere too. Next, I mixed up a batch of epoxy resin. I used just a few pumps of each to start. You could of course use a lot more, but I prefer to use less and mix more up as I go. Just a personal preference on my part. It insures I have fresh resin for the work I am doing and helps in not making too much and wasting any.

Laying in the Fiberglass and Resin

Now for the fun part! I began by brushing on a nice layer of resin on the area the first sheet will go on too. Next, I laid the sheet on to it and used the fin roller to press it into the resin. After that, I generously brushed on resin to the fiberglass repair and rolled it in. Rolling is important for two reasons. First, it gets all of the air bubbles out. Second, it helps distribute the resin evenly. Make sure you are generous with the resin as the next layer will need it to stick to the first.

Once the first layer is on, you can place the second layer on top of it. Make sure that the edges overlap and extend beyond the edges of the first layer. Use the roller to press it in place. Once again, brush a generous amount of resin on to it and roll any air bubbles out. After this second layer, simply repeat the process for each subsequent layer.
When you reach the final layer, once again be generous with the resin. You don’t want to leave any gaps or pinholes. You want just the right amount to saturate all of the fiberglass and fill in the small gaps. But you don’t want the resin to run either. As you work it in with the roller, you’ll get a feel for how much you need.

Letting the Fiberglass Repair Cure

At this point, you’re done with the patch. Let the resin cure before doing any further sanding or shaping. You’ll want to sand this down and start working in fairing compound to smooth the surface. I’ll be covering that in later articles so stay tuned!

Finished and Cured Fiberglass Repair in Anchor Locker

Check out my affiliate links to materials used in this project below:

Here is a link to an article on fixing fiberglass delamination: Delaminated FIberglass Repair

There’s also a YouTube video of this Fiberglass Repair here: Anchor Locker Hole Fiberglass Repair

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