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| Anyone know what Hobie fiberglass rudders are filled with? http://www.hobie.com/forums/viewtopic.php?f=45&t=70436 |
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| Author: | ChuckC [ Mon Nov 14, 2022 9:14 am ] |
| Post subject: | Anyone know what Hobie fiberglass rudders are filled with? |
So, Hobie fiberglass rudders aren't hollow, for obvious reasons, but does anyone know what they're filled with? They are 2 clam shells of a mold reattached, but I can't recall if it's just a mix of resin and micro-balloons or some kind of special filler. It's not expanding urethane foam... Ideas? |
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| Author: | Hammond [ Sun Dec 11, 2022 5:51 pm ] |
| Post subject: | Re: Anyone know what Hobie fiberglass rudders are filled wit |
Ok, this is from memory long ago… … the process starts with a “cookie” of dense foam that had random glass fibers throughout. The A & B clam shell molds were gel coated and glassed, then foam was poured into the glassed molds, the cookie inserted, the parts clamped, then after the foam cured, the flashed excess was trimmed. The 20 an 21 rudders were made this way. The weakness was the foam in the head that would fracture/fail as the clam shell halves were not glassed over the joint. I have a set of failing rudders on a 20 that I’m going to try to salvage before I am forced to buy EPO’s or build blades. The plan is to grind off the gelcoat around the perimeter, vacuum laminate the fracture, then glass over the joint in the head of the blade. This should stiffen the blade and help to keep the foam from fracturing again. With the 20, the EPO blades are a good alternative, with the 21, you may be forced to build new blades as the EPOs are too small for the 21. If I was to build blades, I would start by laminating two marine plywood outer layers with a couple of carbon inner layers. Then shape, glass, and finish the blades. I would wrap the head and leading edges for strength. |
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| Author: | ChuckC [ Mon Dec 12, 2022 7:38 pm ] |
| Post subject: | Re: Anyone know what Hobie fiberglass rudders are filled wit |
Thanks- a buddy (Bill404) and I built a set, starting with shaped mahogany cores that he expertly carved, then I vacuum bagged with multiple layers of carbon, then finish cleared with uv resistant epoxy hot coat. Very cool, very seedy, but a lot of work, hence wanting to build some molds, but I'm thinking vacuum infusion and can make the hollow molded rudder strong enough, just trying to keep the water out, so I'm guessing poured 8 pound foam or foaming epoxy as a filler at this point. |
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