Replacing the Stringers

The stringers were in pretty bad shape, but not rotten all the way through. They had not been installed properly- The center stringer was not straight, and it had also cracked at some time during the boat's life. They were made out of a soft wood, I'm not too sure what kind, but it looked like a fir or something to me. all of them had some pretty bad surface rot, and a few cracks, so I removed them.

I replaced the stringers with laminated plywood. The original stringers were 3/4" thick, and the longest of them was 12' long. So, I took 2 thicknesses of 3/8" plywood and glued them together, giving me the required thickness and length. This is the new plywood stringer next to the old, rotten one- Luckily, enough of the old one was intact for me to use it as a pattern-



To make SURE that the plywood won't rot- Hopefully EVER- I coated them with epoxy-


The installation started with the center stringer. I did a dry fit first, to make sure that it fit. After that was successful, I removed it, then laid down a generous amount of epoxy thickened with fumed silica (also known as Cabosil or Aerosil). I thickened it until it's like frosting or peanut butter- it still has a little bit of 'flow' to it, but holds it's shape. Then, I laid the stringer into it. The 2 x 2 and 2 x 4 that you can see in the photos are there to hold everything in place and square while the epoxy cures.

Next I used more of the epoxy/filler mix to build a fillet up between the hull and the stringer, to add more strength. Over the top of that, I put a layer of 3" fiberglass tape, wetted out with epoxy resin. It's put together far better than the original was- So should be much, much stronger.


Once the epoxy on the center stringer has cured overnight, I can install the two other stringers. They go in pretty much the same as the center stringer- Bedded in thickened epoxy, filleted, and then glassed in. I used temporary braces screwed in to the center stringer to hold the other stringers in place and square until the epoxy cured.



The stringers are now in- Better and stronger than ever before. Now for the cross members- Which will be made of well dried treated lumber. It should last just about forever, even in the rather inhospitable bilge environment.

We'll call these cross members 'frames', which probably technically isn't the right term. They are made from 3/4" treated lumber, which was allowed to dry out inside for several months before using it. It's yellow pine- The particular piece tha I seleced had a nice tight grain sructure and no knots. The floor on this boat is not flat- It is slightly raised in the center, so the frames have to curve a bit. The ones I ripped out were rotten fir- and not as thick as what they were replaced with. The thinner material that was in there before probably would have bent relatively easily to conform to the curve, but the thicker and more dense wood that I was using needed to be shaped, as it really didn't bend.

The three frames that are the full width were original to the boat. They are pressure treated yellow pine. They are just dry fit here, they will be epoxied and screwed in to place. I added one additional frame, to support the cover for the bilge opening that I plan to install just in front of the transom. It will be out of the way, under the splashwell and rear seats, but will provide a means of geting to the bilge if I need to, and help dry it out. This, combined with the opening that I am going to have in the floor under the forward deck, will also allow for air circulation, which should (hopefully!) prevent rot in the future.

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