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Re: Lee wants a new trimaran design...
Ok guys, I gotta say I am gettin' pretty excited about how the boat is turning out so far. I was doing some measuring tonight. I put my strong back on the tip of the stem, and leveled it up. Then I measured back to the center of where I need my mast to be. I ain't blowing smoke here, but I nailed my dimensions within 1/16 of an inch. My mast position with the jib is going to be right next to bulkhead #3, with the center of effort just a little be forward of the center of lateral plane. Perfect! The bulkhead will help provide support to the partner, and the step. I have a 1/2" piece of marine grade plywood I am going to use for the partner and the step. I still plan on covering them with epoxy, and maybe even a layer of 4oz glass.
I also assembled my center aka housings (cross beams). I still need to cover them with epoxy and glass, but I am pleasantly surprised to find that I won't have to shim them up any to let the akas clear the deck. I was looking at the swing radius in my AutoCAD drawings, and since I was looking at the position of the aka end when folded from the side, it looked like it was going to crash against the deck, so I was planning on having to shim it up 3". Turns out, I don't need to shim at all. It was my eyes playing tricks on me in AutoCAD. I also made some 1/8" thick aluminum plates and bent them to match the angle between the sides and the aka housings. I plan on gluing the aka housings to the decks with epoxy, but I still want that extra warm fuzzy feeling that the akas ain't gonna rip up from the boat. I am seriously thinking about putting some water stays on the forward aka housings to help keep the tension on the shrouds going up to the top of the mast. I think I can get away with just attaching the shrouds to the aft side of the aka housings with a chain plate, and that will give me almost a 90deg swing for the sail boom. I never have swung my current boat's sail out to 90 deg even when going dead down wind because I go faster drawing it in a bit, but I like options. The only draw back is that is with the sloop rig. If I run just the main sail, I need to move to my forward mast position, which is 22 inches forward, and I won't get as much boom swing. But wait, without the jib, I don't really need shrouds... well, maybe. I will have to run the numbers again. I have decided to make the mast a rectangle / oval shape that is 2.5 x 4 inches. That is almost double what the formula's said I need, so I should be well within limits. If you want to see how I learned to do these calculations, go here: http://forum.woodenboat.com/showthre...Mast-Diameters . Everybody was very helpful, especially Tad. Check out the pictures:
Here are the aluminum brackets I am making for the aka housings. I also needed some spacers to shim the rudder gudgeons out a bit cause they were crashing against the transom mount when pivoting. I sawed everything up on my table saw with a metal cutting blade. I got an eight foot long 2" wide 1/8" thick piece from Lowes and cut 4 pieces 8 inches long for the brackets, then bent them in the center with a vise and my hands (not bad for a redneck machine shop, eh?). I will drill holes in them and mount them with 1/4-20 stainless bolts (sorry bout the sideways pic):
20230421_182008.jpg
20230421_182032.jpg
Here are the aka housings. They are not anchored yet, I still need to epoxy and glass them:
20230426_215711.jpg
20230426_215715.jpg
And here you can see the deck doubling plywood, partner location, and step base plate. I drew a rectangle on the plywood just past the bulkhead. If you look just to the left of my measuring tape you can see it. That is where the mast partner will be. I am going to make another piece six inches wide, basically a mirror of the step base plate you can see, and anchor it under the deck between the bulkheads. That will give me freedom to make more partner holes and play with the mast positions until I get her helm balance dialed in. I am also thinking about slotting the foot of the mast, drill a hole lateral through it for a holding pin, then make a rail for it to sit on. The rail would have holes drilled through it, so I could move the mast fore and aft to adjust. I dunno, that may be more complicated that I need:
20230426_215724.jpg
Ok guys, I gotta say I am gettin' pretty excited about how the boat is turning out so far. I was doing some measuring tonight. I put my strong back on the tip of the stem, and leveled it up. Then I measured back to the center of where I need my mast to be. I ain't blowing smoke here, but I nailed my dimensions within 1/16 of an inch. My mast position with the jib is going to be right next to bulkhead #3, with the center of effort just a little be forward of the center of lateral plane. Perfect! The bulkhead will help provide support to the partner, and the step. I have a 1/2" piece of marine grade plywood I am going to use for the partner and the step. I still plan on covering them with epoxy, and maybe even a layer of 4oz glass.
I also assembled my center aka housings (cross beams). I still need to cover them with epoxy and glass, but I am pleasantly surprised to find that I won't have to shim them up any to let the akas clear the deck. I was looking at the swing radius in my AutoCAD drawings, and since I was looking at the position of the aka end when folded from the side, it looked like it was going to crash against the deck, so I was planning on having to shim it up 3". Turns out, I don't need to shim at all. It was my eyes playing tricks on me in AutoCAD. I also made some 1/8" thick aluminum plates and bent them to match the angle between the sides and the aka housings. I plan on gluing the aka housings to the decks with epoxy, but I still want that extra warm fuzzy feeling that the akas ain't gonna rip up from the boat. I am seriously thinking about putting some water stays on the forward aka housings to help keep the tension on the shrouds going up to the top of the mast. I think I can get away with just attaching the shrouds to the aft side of the aka housings with a chain plate, and that will give me almost a 90deg swing for the sail boom. I never have swung my current boat's sail out to 90 deg even when going dead down wind because I go faster drawing it in a bit, but I like options. The only draw back is that is with the sloop rig. If I run just the main sail, I need to move to my forward mast position, which is 22 inches forward, and I won't get as much boom swing. But wait, without the jib, I don't really need shrouds... well, maybe. I will have to run the numbers again. I have decided to make the mast a rectangle / oval shape that is 2.5 x 4 inches. That is almost double what the formula's said I need, so I should be well within limits. If you want to see how I learned to do these calculations, go here: http://forum.woodenboat.com/showthre...Mast-Diameters . Everybody was very helpful, especially Tad. Check out the pictures:
Here are the aluminum brackets I am making for the aka housings. I also needed some spacers to shim the rudder gudgeons out a bit cause they were crashing against the transom mount when pivoting. I sawed everything up on my table saw with a metal cutting blade. I got an eight foot long 2" wide 1/8" thick piece from Lowes and cut 4 pieces 8 inches long for the brackets, then bent them in the center with a vise and my hands (not bad for a redneck machine shop, eh?). I will drill holes in them and mount them with 1/4-20 stainless bolts (sorry bout the sideways pic):
20230421_182008.jpg
20230421_182032.jpg
Here are the aka housings. They are not anchored yet, I still need to epoxy and glass them:
20230426_215711.jpg
20230426_215715.jpg
And here you can see the deck doubling plywood, partner location, and step base plate. I drew a rectangle on the plywood just past the bulkhead. If you look just to the left of my measuring tape you can see it. That is where the mast partner will be. I am going to make another piece six inches wide, basically a mirror of the step base plate you can see, and anchor it under the deck between the bulkheads. That will give me freedom to make more partner holes and play with the mast positions until I get her helm balance dialed in. I am also thinking about slotting the foot of the mast, drill a hole lateral through it for a holding pin, then make a rail for it to sit on. The rail would have holes drilled through it, so I could move the mast fore and aft to adjust. I dunno, that may be more complicated that I need:
20230426_215724.jpg
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