Someone asked about the differences in the length between the plans and the kit. I'll have to measure it tonight. The tub profile has definitely changed in the front. I'll try and get a pic of it to compare.
I'm planning on using 3/8" carbon booms and turning 1/2" od 3/8" id tubing down to 13/32" which appears to be the dia of the holes in the sponsons and tub sides.
I have built a few of the 90 - 101's from the plans and the sponsons seem a lot longer. I used i/2" heavy wall aluminum booms, but used 5/8" aluminum when I built an OPS 90 powered one.
Tub sides are 43" long so tub will finish up a tad longer with the nose block. Tub width is 3 1/4" on the inside, 3 5/8" on the outside. The tub is also 1/4" higher than the plans. Tub sides are laminated 1/8" on the inside with the tab cutouts for the bulkheads and 1/16" on the outside. Tub top and bottom are 1/16" ply. As you can see from the photo, the sponsons are much larger than the plans!
Well the sides are being laminated. One of the most important steps, making sure you have a right and left side. I turned down some 13/32" plastic buttons to keep the sides in allignment, seemed to do the trick. A piece of 8" channel should be plenty of clamping force.
Finally getting back at it after a delay waiting for 13/32" brass tubing and the carbon booms. Did some mocking up and next step is match sanding the sides of the tub. Need to pick up some hardwood dowls for the turnfin. Going to be making boom supports for the sponsons out of 3/4" aluminum with most of that turned into swarf.
Slow progress, but made some. Finally found my long sanding board to get the tub sides flat and evened up. Turned some 3/4" round stock into boom supports for the sponsons. Joe said the 13/32" brass tubes will pull out from the cornering forces and IMHO a soldered on washer is a bit crude so I decided to take on a bit more work and make billet boom supports. I'll be slitting them and using shaft collars to hold the booms so I can adjust toe in or out as needed. Also a bit more work as after I assemble the sponsons I'll need to bore out the 13/32" holes to 1/2" to glue in the boom supports.
Finally made a tub jig. Next step will probably be the engine mount and figuring out where to locate it before gluing up the tub, or I'll work on the sponsons.
john with two of the gas Jaes the aluminium booms don't glued well and rotated so with the solid section with wood I haven't had any more issues.....I have to agree that using divinycell is another story with zero issues. Gill
At least 20+ boats including at least 8 or more twins built using divinycil sponsons with no tubes pulling whether aluminum fiber glass or carbon fiber.