I promised in an earlier post to update you on my re-bottoming project.
I purchased this 17' Tatman and it's in excellent shape, except it was 18 years old and the UHMW plastic on bottom was getting very brittle. The screws were working loose and the plastic had to go. There was even a slow leak along one row of the screw holes where they missed the framing member.
I decided that instead of replacing the UHMW sheeting on bottom, I would instead try a slick bottom treatment called Wetlander.
To make up for some of the protection and strength I was giving up, I decided to try a single layer of Kevlar fabric (11oz) and multiple coats of WEST system epoxy.
I removed the plastic and this is what I found:
So I filled each hole with WEST system epoxy and a dowel or matchstick or toothpick, depending on what would fit.
When all that was set up, I sanded and then cut a single piece of 11 oz Kevlar fabric to fit the bottom. In retrospect, I would have been better off to put the Kevlar on untrimmed and then grind off the edges. But it didn't go too badly.The photo above shows the Kevlar after it has first been laid. WEST system, then this piece of Kevlar, then a good soaking / rolling of WEST system.
Below is a closeup of the edge, which I grinded off and sanded to taper down a bit.
And below is after I have coated with the Wetlander primer and top coats. As you can see I also used the Wetlander on the little side panels just for a design accent. The plastic piece leaning against the stem is a UMHW polyethylene product called Tivar 88.
In addition to the stem piece, above, I had two 10-foot strips cut of 1/2" Tivar 88, with angles for securing to the chine battens along the middle of the boat on each side. One of these pieces is shown below:I'll bevel each end down before mounting these to the chine battens.
These go on with the large flat side (bottom as shown) up against the chine battens, with the sharper angle (45) down when mounting — up when the boat is turned up right. The 30 degree angle works nicely coming off the bottom.
I'm planning to use 1" stainless steel wood screws, counter-sunk just below flush. The screws I have are threaded all the way up. I'm not sure that's best, because I'd like to leave a little wiggle room around the screws where they pass through the plastic. This is because of the expansion and shrinkage of the plastic that occurs with temperature shifts. My thinking is I need a slightly oversized hole through the plastic, then a taper into the wood of the right size for the screw, with a small counter-sink up top.
What do you fellows (& ladies?) think?
Also, I'm thinking of using gaffers tape or gorilla tape to just tape these plastic strips up and drill the whole hole, as it were, with one bit at one time. Anyone have advice on this? If that works, it looks to me like I could tape it up, drill and screw, one at a time, starting at center and working out both directions. I have to map my holes ahead of time to look out for existing screws plus the plugged holes from the screws previously holding plastic in place.
Also, another cry for help:
I'm thnking of, just prior to putting each screw in, squirting a little bit of 3M 5200 marine sealant in the hole...to put a little flex-quasi-seal around those screws through the plastic... what do you think folks?
Thanks in advance for any suggestions...