Junkyard Dog
19 May 2015 | Bodkin Inlet/Chesapeake Bay
Capn Andy/hot and humid
More little details are on order, mostly from Defender Marine in Connecticut. There are other online boat supply stores now, shop and save. I did stop by West Marine, who is no longer as convenient, having closed their Pasadena store. Now it it a further drive of 10-15 miles to get to the nearest store.
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West Marine had a cheap looking shackle made of stamped stainless steel by Harken. It has about the same working load as a more substantial and expensive shackle made by Wichard. Either shackle would break long before any of the other components in the running back stay, where it will be used, would break. I was glad I brought the Ronstan double block with becket with me to the store and could find out that I had got the model number of the block wrong, it took the next larger shackle. Still the weakest link in the chain.
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New Dynema was ordered to make new lashings for the shrouds. Against a lot of advice.
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The outrigger canoe project is a lot like my new cat. It lays almost in my path, beconning me.
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Some correspondence brought me back into some of the outrigger design and it was enjoyable to relearn some of the techniques I used when I designed the boats which now exist and await completion. I went back into the design software because I read that someone had evidence that waterline beam had a bit more effect on performance than wetted surface. That is, a narrow hull that has a bit more wetted surface might be faster than a hull with minimum wetted surface but a bit more beam.
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The Kiribati style vee hulled canoe hull could be roughly approximated by an equilateral triangle for the underwater cross section. The other hull that was built is a sharpie style hull with a flat bottom and vertical sides. The underwater cross section is a rectangle. I arbitrarily decided to make the beam two times the draft, so it came out something like needing 7 inches of water to float and had 14 inches of beam. These hulls are aiming at about 500 lbs of displacement at design water line, which results in a total cross section area amidships of about 100 square inches. Using this convenient number we can find out how much hull surface would run from waterline to waterline in the minimum wetted surface, a semicircle cross section, and the answer is about 25 inches. The sharpie hull comes out about 28 inches and change, and the Kiribati hull comes out about the same 28 inch range.
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So, we expect the two hulls we have built to have similar resistance at low speed paddling. What happens later when the hulls speed up depends more on wave making resitance. At this point I expected a redesign of the sharpie hull to a more square cross section would result in less cross sectional area, less resistance. A simple square shape cross section at 100 square inches would result in 10 inches of draft and 10 inches of beam, and 30 inches from waterline to waterline. Can't be. Intuitively it didn't seem right. This shape would have more surface than the rectangle. It turned out by looking at this problem using calculus and also graphing the different cross sections, the original stab in the dark 7 inch draft and 14 inch beam of the original sharpie hull was remarkably close to an optimum for a rectangular shape, that is, beam twice draft will work very well.
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Down at the dock I decided to work on the bails for the headstay and inner forestay. These are stainless steel straps that came along with the aluminum mast and had been tangs for lower shrouds. Now they are up at the top of the mast, wrap around forward, and are bolted with the eye of the stay in between. To get them wrapped around the mast I could just run 1/2" bolts through the end of both tangs and cinch them together. The headstay meets the mast at over 40 degrees and the inner forestay at about 18 degrees.
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Up at the boatshed I began the search for 1/2" bolts. There is a lot of stuff there and it has been growing more and more disorganized. I began to sort things out while I was looking. Then I began removing more and more stuff, clearing out space, cleaning, organizing bolts, nuts, pins, sailing gear, tools, and soon there was a huge pile of gear outside the shed. I was glad to come across things that I had looked for in the past. I began then to put it all back together, boat style, everything in its place.
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Dottie the Safety Officer arrived along with Bev Rocco, ship's artist, to find me covered with grime and surrounded by piles of grimy sailboat gear.
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The picture is called "Junkyard Cat" from Saatchiart.com by Kathleen Rice. It is available for purchase.