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I completed the tub reinforcement project yesterday with some help from Dan (RXP'n in MI). Thanks again Dan!!
I pulled the motor and gas tank, cut the 'feet' out entirely, then beveled the edges of the holes where the feet were and sanded the entire tub area with 60 grit on a grinder to rough it up and get it ready for bonding, then cleaned it thoroughly with water, then with lacquer thinner. I put thin styrofoam sheets in the feet holes just as a way to keep the cloth/resin from sagging into the holes and basically re-creating the feet.
I had two yards (x 50 inches) of 5.8 oz carbon fiber, as well as similar quantities of fiberglass mat and fiberglass cloth, and lots of West System 105 epoxy and 205 hardener. I used varying sizes of fiberglass cloth and mat for the first three layers, basically sealing up the holes and building some thickness over the holes, overlapping over most of the tub and up to the sides and top of the tub area. After the 3 layers of 'glass, we switched to carbon fiber, and laid in 4 layers of that, wetting out all layers pretty liberally with the epoxy resin. Each layer of 'glass and CF was a different size and shape ... roughly half of them reached up and over the 'upper shelf' of the tub to help spread the weight and distribute the load over the entire front of the ski. Hopefully you can see in the last pic where I 'anchored' the layers onto the upper shelf, but they anchor between the gas tank brackets, in front of the tank brackets, and in the front middle (big chunk there).
I had cut templates out of plastic sheet for all the different layers of 'glass and CF, then cut the layers of 'glass and CF, trial fit them dry, and re-trimmed as needed, so when we started wetting them out and laying them in we could proceed quite rapidly. I did this so that the entire project would be a 'primary bond' with all the layers chemically bonding due to laying them in on top of each other while still wet. Far faster, far stronger, far easier than laying in, letting it dry, sand it, lay in next layer, etc. Laying in all seven layers took us roughly two hours. We used paint brushes to brush on the epoxy for all the layers, and used brushes and our gloved hands (rubber gloves are a necessity) to smooth out all the layers, and eliminate air and resin bubbles.
In case anyone is curious, the weight of all the materials used is approximately 7 - 8 pounds max, most of which was the 60 ounces of resin/hardener. Approximate cost of materials used was $250; if someone used only fiberglass and typical fiberglass resin the cost would be significantly less (but so would the strength).
In order to do this all in one session I really needed two people ... it would have been extremely difficult to do this by myself, so if you try a project like this, line up a friend to help out.
I will try to attach a few pics ...
I pulled the motor and gas tank, cut the 'feet' out entirely, then beveled the edges of the holes where the feet were and sanded the entire tub area with 60 grit on a grinder to rough it up and get it ready for bonding, then cleaned it thoroughly with water, then with lacquer thinner. I put thin styrofoam sheets in the feet holes just as a way to keep the cloth/resin from sagging into the holes and basically re-creating the feet.
I had two yards (x 50 inches) of 5.8 oz carbon fiber, as well as similar quantities of fiberglass mat and fiberglass cloth, and lots of West System 105 epoxy and 205 hardener. I used varying sizes of fiberglass cloth and mat for the first three layers, basically sealing up the holes and building some thickness over the holes, overlapping over most of the tub and up to the sides and top of the tub area. After the 3 layers of 'glass, we switched to carbon fiber, and laid in 4 layers of that, wetting out all layers pretty liberally with the epoxy resin. Each layer of 'glass and CF was a different size and shape ... roughly half of them reached up and over the 'upper shelf' of the tub to help spread the weight and distribute the load over the entire front of the ski. Hopefully you can see in the last pic where I 'anchored' the layers onto the upper shelf, but they anchor between the gas tank brackets, in front of the tank brackets, and in the front middle (big chunk there).
I had cut templates out of plastic sheet for all the different layers of 'glass and CF, then cut the layers of 'glass and CF, trial fit them dry, and re-trimmed as needed, so when we started wetting them out and laying them in we could proceed quite rapidly. I did this so that the entire project would be a 'primary bond' with all the layers chemically bonding due to laying them in on top of each other while still wet. Far faster, far stronger, far easier than laying in, letting it dry, sand it, lay in next layer, etc. Laying in all seven layers took us roughly two hours. We used paint brushes to brush on the epoxy for all the layers, and used brushes and our gloved hands (rubber gloves are a necessity) to smooth out all the layers, and eliminate air and resin bubbles.
In case anyone is curious, the weight of all the materials used is approximately 7 - 8 pounds max, most of which was the 60 ounces of resin/hardener. Approximate cost of materials used was $250; if someone used only fiberglass and typical fiberglass resin the cost would be significantly less (but so would the strength).
In order to do this all in one session I really needed two people ... it would have been extremely difficult to do this by myself, so if you try a project like this, line up a friend to help out.
I will try to attach a few pics ...
of my ski I see these stress cracks that run longitudinally with the ski, but there is one spot right by the fuel tank foot on the port side. I think to myself "damn, I want to build the engine - not itch for a week from fiberglass. I really didn't want to do the project, but in the end I am glad I did. It doesn't take a pedigree to realize that there is no good reason to put the feet in the inner hull. Damn - the inner hull was 3/8" thick in places. That is much thicker than a boat! Very strong and shouldn't flex that much. I might say that the styrofoam they used is very soft. Bascially the feet will take all the impact. There is an older post where the user completely cut out the tub, but I agree with VERN on this one - that reduces the strength too much. BTW - I did not inject foam after removing the feet because I did not believe it was necessary.
??? You have to fill the void from the cut feet with something. I rough cut the syrofoam and then hot glued them into the hull just to hold them in place. You can see the cut piece in the previous post. I used a wood rasp to form the styrofoam to fit in the hole after roughing it out.
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