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Bigjim · 30-08-2019, 10:12

I stepped on my polycarbonate hatch a couple of weeks ago and broke it. So, I scrambled to replace it. A local plastic company, gave me an estimate for $1,400. I thought that was ridiculous. Then, I had to figure out an alternative.

The first issue was building a temporary hatch which I fabricated from a couple of pieces of 1/4 plywood epoxied together in a slight arch. The old hatch had a 1/2 arch over 32 inches. I built a handle on top from strips of plywood and epoxied together. Once that was done, I painted it to protect it from rain and sun.

Next, I had to devise a way to rebuild the hatch. Using plywood would have worked but I didn't think it would be very pretty. So, I figured I'd use plywood as the base and then add cedar strips to the top and epoxy the whole thing.

Below you will see a series of photos chronologically following the build. The hatch is nearly finished. I put the 5th coat of epoxy to the top and it is currently setting up. When that's done I'll start laying on the varnish. So, far the hatch looks beautiful.

I started with two sheets of 1/4 inch plywood. I had to use 1/4 inch because I have a limited amount of vertical space. The total thickness could not exceed 3/4 inches.

I created two forms from 2x4s to create the arch. I cut the arch into the 2x4s and sanded them smooth. I epoxied the two sheets of plywood together and clamped them to the 2x4s so they would set up in the arch.

Next, I bought 4 foot 1/4 inch oak strips and epoxied them to the plywood to form the outside edges of the hatch. I left the bottom strip off to make it easier to add the cedar strips.

Working with the cedar was a bit harder. The strips came with a bead and cove already cut into the wood. But I needed to add beads and coves to my oak edges too to fit them all together. So, I bought router bits from the same company that sold me the cedar.

Routing the cedar and oak was very demanding. Setting the depth of the router bit was tedious and hard to get perfect. I wasted several pieces of wood getting them right. The second hardest part is cutting the cedar to the right length.

Eventually, I had a bunch of strips ready to use. I mixed up a large batch of epoxy resin and wet out the top of the hatch. Plywood can suck up a lot of resin so make sure you have enough and wet out the base well.

I worked in 6 to 8 inch strips sliding the cedar pieces into place. In the center I wanted to break up the pattern by inserting another oak strip. This also allowed me to compensate for length as the cedar came in .75 inch widths. Using the oak strip in the middle allowed me to adjust the overall length without having to trim any cedar strips.

I alternated the strips using darker pieces every now and then to produce a nice pattern. Finally, the cedar strips were in place. I mixed up another batch of epoxy and wetted out the top of the hatch thoroughly so the wood would be glued entirely without any voids.

I cut a sheet of peel ply and rolled it out over the top of the hatch. I smoothed it out and made sure there was plenty of epoxy on the top.

At this point, something happened that I had not expected. The cedar, after being thoroughly wetted out with epoxy, was a bit slippery and it started to pop up from the arch. It turns out that I had cut the strips about 1/8th inch too short and the beads were not holding in the coves. Luckily, I had some extra polycarbonate pieces laying around and used them to help me clamp down the strips. Polycarbonate does not adhere to epoxy. Disaster averted!

The next day I took off the clamps and pulled up the peel ply. Most of the hatch looked fine. But some of the cedar had been chewed up by the router and there were some small gaps in the joints where it met the oak frame.

I mixed up some more epoxy with saw dust I pulled out of the shop vac and filled all the gaps. I had to do this a couple of times because the epoxy had some shrinkage as it set up and a few other gaps appeared in other places.

Once the hatch was mostly finished, I brought it over to the boat to dry fit it. Unfortunately, I discovered the aluminum tracks for the hatch were not completely parallel. So, I was worried that the hatch would bind where the tracks narrowed. Luckily, it all fit perfectly.

I brought the hatch back home and added a layer of fiberglass to the top and bottom. When that set up I painted about 3 coats of epoxy to each side. Then, I epoxied the top and bottom handles to the hatch. The top handle was built using strips of 1/4 plywood. The bottom handle was cut from a single piece of oak. Both were formed into the same 1/2 inch arch to provide additional strength to the hatch. Another oak strip was cut and epoxied to the bottom at the back end for further reenforcement.

With all these features, I don't I'll have to worry about this hatch breaking when I step on it. Once I install it later this weekend, I'll most some more pictures.