So here's the deal- I've found another paddler to race the Cheat with me in my Old Skool end-hole C-2 (actually, it might be from before they even had Skool...), but I've realized that the cockpit rims are so gunked up from repairs to get skirts on and off easily, and fairly rotten to begin with, so I'm thinking my best bet is to grind them off and build them from scratch. I've done a cockpit rim of a boat before by shaping a piece of minicel foam and glueing on and laying up the rim that way, so I don't feel like I'm in over my head in doing this, but I've also read that you can do it by using a piece of 3/4 in plastic tubing, and I'm wondering how well this works? It seems like a much simpler way of doing it. How do you get the top of the rim to be flat? Also, what are considerations for releasing the tubing when it's done (wax, PVA, or is it good to go on it's own? Also, what layup would you reccomend? My last cockpit rim came out a little bit light in some spots. Any other advice?
Thanks
Jeremy
Cockpit Rim repair/rebuild for the boatbuilders out there
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RodeoClown
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I did one with tubing. It was the PVC? stuff from the plubing aisle at Home Depot. The only problems I had was where I joind the ends the excess hot glue made a bump and i got some air bubbles in the void that is created by the roundness of the tubing on the deck. maybe this could be filled with some type of putty. The top wasn't round, but flat. It didn't come out the prettiest I've ever seen (first attempt at a rim), but it is strong and holds a skirt well.
Theres my 2 cents
Paul
Theres my 2 cents
Paul
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Sir Adam
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Another way...
If you go to Home Depot or any hardware store you'll find sealing foam - it looks kind of like a hose, except it's solid (as a site note, an actual round garden hose works as well). I hot-glued the hose (or foam the second time-I think it works better, but perhaps my technique simply improved 
) around the cockpit, placed saran wrap over the form (e.g. hose or foam), but not inside the boat (where the glass will be bonding too), letting it instead drape over the outside of the boat (helping reduce resin splatters and other mess). Once the cloth was laid up (and partially cured..e.g. "green" I trimmed the cloth and pulled the foam out (leaving most of the saran wrap. Once cured the saran wrap pulls right out.... Alternatively you CAN get it out (the form...in this particular case the hose) after trimming with some tugging.
Remember to sand down the edge of the glass so it doesn't cut your skirt. Some tape the edges too...not a bad idea, and it makes it look a bit sharper...
) around the cockpit, placed saran wrap over the form (e.g. hose or foam), but not inside the boat (where the glass will be bonding too), letting it instead drape over the outside of the boat (helping reduce resin splatters and other mess). Once the cloth was laid up (and partially cured..e.g. "green" I trimmed the cloth and pulled the foam out (leaving most of the saran wrap. Once cured the saran wrap pulls right out.... Alternatively you CAN get it out (the form...in this particular case the hose) after trimming with some tugging.Remember to sand down the edge of the glass so it doesn't cut your skirt. Some tape the edges too...not a bad idea, and it makes it look a bit sharper...
Keep the C!
Adam
Adam
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John Coraor
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Cockpit coaming
Laying up cockpit coamings over 3/4 in. O.D. tubing was standard procedure for boats built at Penn State when John Sweet was still building there (Nittany Valley Boats).
PREP: I don't recall using PVA or mold release on the tubing, but it couldn't hurt if you have it available as long as it doesn't interfere with attaching the tubing to the cockpit edge. Use a hot glue gun to attach the tubing to the edge of the cockpit cut-out. You want to cut your strips of cloth on the bias (diagonally across the weave rather than parallel to the weave) because it will bend more readily that way. Strips should be 4-6 in. wide and just a little more than 1/2 the circumference of the cockpit. I seem to recall using 4 layers (you don't want a weak coaming), although 3 would probably work. Sand like hades under the deck all around the cockpit several inches deep.
LAYUP: I find it easier to layup one half of the coaming at a time, but to continue with the second half before the first gels. Wet-out each strip on a board and lay them in place one at a time with a healthy amount of overlap under the deck and some cloth extending past where you expect your finished coaming edge to be. Stagger the starting point around the coaming about 1/2 inch for each layer so that you don't have all layers starting at the same point, creating a stress riser. Remember the staggers will also be the point of overlap for the other half of the coaming. Make sure that all layers lie flat in contact with the layer underneath with no bubbles.
FINISHING: Watch carefully as the coaming gels. When it is "green" (i.e. hard enough that the layers don't separate, but not fully cured) is the best time to trim the final coaming edge. The best tool is a curved linoleum knife that has been thoroughly sharpened. At this point in the curing process you can cut through four layers of glass and resin very easily and make a nice clean cut to remove the excess material. The ease of doing it at this stage is well worth it. If you cut before the layup starts to gel you'll know it quickly because it won't cut readily and layers will separate messing up your job. If you wait too long the layup will be very hard and you will probably need to wait until it fully cures and use a sabre saw and grinder to finish the edge. Similarly, it is easiest to pull out the tubing at the green stage when it is still somewhat flexible before being fully cured. Just start at one end, work it loose and then pull the tubing out from under the rim working around the cockpit.
I have to disagree with the previous post. A coaming formed over tubing WILL usually be somewhat circular on top. However, you're going to cut it off before the curve gets more that 3/4 of the way around to the deck. If a flat coaming is REALLY important, then you're going to need to use something other than tubing that gives you a flat surface on top.
P.S. Sometimes we used 3/4 in. O.D. ethafoam tubing instead of PVC. The was even easier to use as it would collapse more reaidly when you go to pull it out.
I hope that this is helpful.
PREP: I don't recall using PVA or mold release on the tubing, but it couldn't hurt if you have it available as long as it doesn't interfere with attaching the tubing to the cockpit edge. Use a hot glue gun to attach the tubing to the edge of the cockpit cut-out. You want to cut your strips of cloth on the bias (diagonally across the weave rather than parallel to the weave) because it will bend more readily that way. Strips should be 4-6 in. wide and just a little more than 1/2 the circumference of the cockpit. I seem to recall using 4 layers (you don't want a weak coaming), although 3 would probably work. Sand like hades under the deck all around the cockpit several inches deep.
LAYUP: I find it easier to layup one half of the coaming at a time, but to continue with the second half before the first gels. Wet-out each strip on a board and lay them in place one at a time with a healthy amount of overlap under the deck and some cloth extending past where you expect your finished coaming edge to be. Stagger the starting point around the coaming about 1/2 inch for each layer so that you don't have all layers starting at the same point, creating a stress riser. Remember the staggers will also be the point of overlap for the other half of the coaming. Make sure that all layers lie flat in contact with the layer underneath with no bubbles.
FINISHING: Watch carefully as the coaming gels. When it is "green" (i.e. hard enough that the layers don't separate, but not fully cured) is the best time to trim the final coaming edge. The best tool is a curved linoleum knife that has been thoroughly sharpened. At this point in the curing process you can cut through four layers of glass and resin very easily and make a nice clean cut to remove the excess material. The ease of doing it at this stage is well worth it. If you cut before the layup starts to gel you'll know it quickly because it won't cut readily and layers will separate messing up your job. If you wait too long the layup will be very hard and you will probably need to wait until it fully cures and use a sabre saw and grinder to finish the edge. Similarly, it is easiest to pull out the tubing at the green stage when it is still somewhat flexible before being fully cured. Just start at one end, work it loose and then pull the tubing out from under the rim working around the cockpit.
I have to disagree with the previous post. A coaming formed over tubing WILL usually be somewhat circular on top. However, you're going to cut it off before the curve gets more that 3/4 of the way around to the deck. If a flat coaming is REALLY important, then you're going to need to use something other than tubing that gives you a flat surface on top.
P.S. Sometimes we used 3/4 in. O.D. ethafoam tubing instead of PVC. The was even easier to use as it would collapse more reaidly when you go to pull it out.
I hope that this is helpful.
Great post John.
One thing I would add - I have had great success using FG cloth cut on the bias (ie:45 degrees to the weave). The edges will not unravel and the bias cut cloth will confirm to any shape.
I usually use 6 layers of 6oz cloth (haven't had one break yet) - but I'll put 2 layers on at a time and work my way around. I prefer to have the boat flat and layup the whole rim in 1 shot.
The tubing found at Home depot is sometimed flattened by being on the roll. It helps to heat the hose a bit to soften it and work it around the rim area.
F
One thing I would add - I have had great success using FG cloth cut on the bias (ie:45 degrees to the weave). The edges will not unravel and the bias cut cloth will confirm to any shape.
I usually use 6 layers of 6oz cloth (haven't had one break yet) - but I'll put 2 layers on at a time and work my way around. I prefer to have the boat flat and layup the whole rim in 1 shot.
The tubing found at Home depot is sometimed flattened by being on the roll. It helps to heat the hose a bit to soften it and work it around the rim area.
F
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John Coraor
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Building a cockpit coaming
My reference to 4 layers was using 10 oz. glass for a total thickness of 40 oz. of cloth, which is comparable to the 36 oz. total thickness of 6 layers of 6 oz. cloth. So we're both recommending about the same thickness coaming.
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RodeoClown
- BlackFly Canoes
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Thanks for all the tips/tricks. In the end, I didn't like the way the tubing was sitting on the boat, so I ended up shaping some strips of minicel (I had some long strips of the right size left over from the last one I did). The tip about pulling the form out while the glass is still "green" was a big help, since I didn't end up with bits of foam stuck to the bottom of the rim.
Then I carried the boat outside on my head and dropped it on the grass and put two decent cracks in it- at which point I decided that it's just too iffy to try and race it- I'd give it about a 50% chance of making it down the river. maybe another time...
Jeremy
Then I carried the boat outside on my head and dropped it on the grass and put two decent cracks in it- at which point I decided that it's just too iffy to try and race it- I'd give it about a 50% chance of making it down the river. maybe another time...
Jeremy