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AeroE

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About AeroE

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  1. The closer the skeg is to the longitudinal center of rotation, the more it affects side drift in a wind. If directional stability is needed, then the size has to increased. Nearer the stern, the area can be reduced to provide sufficient directional stability, plus a smaller degree of lateral drift. (I'll have to read up on the naval architect's vocabulary for the air vehicle analogs.) Jeff, What you "need" is an experimental mule with four or five skeg receptacles ranging from the boat's design CG to the stern. The construction part wouldn't be to much more difficult if the manual retraction/extension is eliminated. After about 15 seconds of thought and no sketches, I would start with a long trunk from just behind the cockpit all the way to the stem, either with a series of slots where a skeg could be slipped in and secured with a wedge, or build skegs into the trunk from the start to be deployed one at a time. Some minimal ballast might be needed forward of the cockpit to trim the boat.
  2. I have a spreadsheet set up that allows quick calculation of the effect of changing the shape of the waterline on sinkage. I integrate a fourth order polynomial equation to get the waterline area, then calculate the volume required for a particular displacement. I'll post a typical example if I can figure out what I need to do to host the picture(s). I'll put the example I intended to post into words. Waterline length: 15 feet, beam: 20 inches, location of maximum beam: 0.55(15) feet from the bow, entry angle: 7 degrees, required displacement: 50 pounds, water density: 62.4 pcf. The slope of the water line plane is zero at the maximum beam. The resulting equation for the waterline shape (half shape along the centerline) is buttline, y = 0.000 000 029 71x^4 + 0.000 014x^3 + 0.000 884x^2 + 0.1222X. Multiply the integral by 2 to get the waterplane area. The waterplane area is 15.81 square feet, so the sinkage to support 50 pounds is 0.61 inches. Not much. But, the perimeter length is 30.23 feet, so the added wetted area is approximately 1.5 square feet (using a constant area cross section). This squares with a bunch of layout work I made last summer; these little boats have wetted areas that are very sensitive to minor changes. (I was working on minimum wetted area shapes for the E340 race which requires solar power and battery storage with no other motivation for propulsion, so the power required to move the boat has to be extremely small in order to complete the long race. Or even get to the end of the first day of the race!) Fooling with length in addition to the beam can screw up the stability simply due to the loss of volume along the length of the boat even though that volume might be relatively close to the centerline of the boat, it's still contributing small righting moment. This is the reason long boats with beams and reasonably similar cross section shapes equal to a shorter boat can yield more rolling stability. It's also the reason very short kayaks get fat, the volume and stability has to come from some place and there ain't much place to get it from lengthwise.
  3. I have made some sketches of a SOF surf ski, but after paddling a V8 (owned by the dealer in Olathe!), I'm way less enamored by the idea unless the seat includes drainage. If I want to sit in a puddle of water, I'll get a wash tub. The bailers work pretty much well enough to keep the cockpit from completely filling, but the boats are light years from "dry" inside. That's probably okay for skiing in surf for short periods, but not for cruising, floating in the Ozarks, or racing. In my humble opinion. Seats with drainage and floor boards go a long way to cure that problem.
  4. Avoid any sealer containing silicone at places where a permanent patch follows. It won't be permanent.
  5. I caught the error when I lofted the boat in a graphics program, but it's so obvious that there's no doubt.
  6. Tie the noodles in before skinning. Access for replacement is a good reason for two piece skins. Noodles alongside the cockpit exclude water at the widest part of the boat to aid stability if the boat is full of water, besides excluding as much water as feasible. Those are easier to remove and replace.
  7. Build a finished boat and a bare frame to raffle or auction to help fund the project. The bare frame would be either for the buyer to finish or as a display as art. Several paddles, too. I think I would build one boat to start and use that one as the training aid and for development of patterns and fixtures, then pile into the 20 boat project. Man loading on a single boat will be a little bit of a problem as every kid needs to get hands on and not just observe, but the lashing should go quick! Maybe two training boats, slightly staggered in the schedule. Standardize the boats and limit the customization to finish and decoration.
  8. Make a little "dollar" patch to cover the tear. Borrow your wife's pinking shears to cut out a circular patch to cover the hole. Bond it on with heat bond tape from the fabric store; the wife might have some of that, too. You'll need to remove the paint at the bond joint. Iron the edges down tight, then repaint. The repair will be hard to find from more than a few feet away. If anyone is bending over to inspect your boat, give 'em a boot in the butt.
  9. I'll bet the bonded fabric will release with heat if it's ever necessary to reskin your boat. I guess there will be an aftermarket for good clothes irons now. An iron sold for aircraft fabric might be required for progress in boat building.
  10. Boiled linseed oil is just about the worst choice possible for any wood project and particularly a boat. It offers no moisture protection, and requires days and days to reach anything like a cured condition. It looks great for a while, but there are better choices, such as one of the polymerized versions. Linspeed and Birchwood Casey's Tru Oil are two, although not in the quantity required for a boat frame.
  11. A sail is about useless in the head wind that seems to favor this race. The MR 340 is an endurance race. Not a Saturday night dosey doe with a pretty gal. Whether the Missouri River is too dangerous is a matter of opinion from an assessment of one's personal risk tolerance and is not a universal opinion. Or particularly defensible. The first two legs check in times designed to push the paddlers in order to eliminate racers that will be too slow to complete the race. This year a new record time was set; 35 hours, 58 minutes. Pretty cool, that team earned the record. I have no idea about how the sponsors arrived at the 88 hour limit, but it's a practical limit on the demands from the race volunteers, and it's obvious that there's no point in a longer period, 88 hours is sufficient for every paddler that wants to complete the course but isn't interested in being the first boat to finish. Finishing the race is a considerable accomplishment.
  12. When I was active in Scouting, we learned a suite of lashes for different purposes. Old scout manuals included tables and chairs, albeit more rustic than necessary. That idea does make wheels start turning ...
  13. Thanks. I'm not necessarily looking for "free" per se; I've made a 3D model in which I modified the 12 foot boat's off sets to ~14 feet overall length in order to understand how a boat based on the 12 footer's parts might look. I think I kept one part unchanged in the second or third pass.
  14. A linked .pdf file can be found with a search, but the file is corrupted. If there is a direct link from the Kudzu Craft web site, it's more than well hidden. I've looked through every page of this forum for information with no luck. Please advise if they have been pulled for use.
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