Ok Keith:
Here are the extension tubes:
I ordered mail order 6160 T6 aluminum 1.5" dia (1/8" wall thickness), 4 pieces pre-cut to 18 inches long (they were around $24 bucks total). What I didn't realize before starting is the tubing Hobie uses has flat spots on the top and bottom (inside) to make the AKA's stronger (sides are 1/16 wall and the top and bottom are 1/8" wall). Before starting I had to beat down the ends of the rods with a ball peen hammer to make them oval shaped, I could then sculpt and file the ends (freehand) so they fit inside the tubes. The flattened ends stick into the AKA bar 3 inches per side, you kind of want the fit and roundness to be within a couple thousandths (really time consuming to do free hand), if you have access to a machine shop ( I don't, so everything was done freehand with a disk sander and file), it will save a bunch of time. Final dimensions on the ends are 1.498 dia +0.000 -.002, and the flats was 1.285 +0.000 minus .002" 3 inches long flats on mine anyway. In retrospect, I could have used solid rods instead of tubing.
I then measured from the centerline of the hinge on the AKA joint out 32" inches and cut the bars. The finished bars slide easily into the tubes.
On the rear AKA bars I had to drill out 2 rivets where the bungy for holding the AMA's in go, those same holes were then used with two 8/32 screws threaded into the new extension bar to hold the extension bars on.
Here is a pick of the completed AKA bar with the extension installed, like I said the extensions are removable but you would need to make up shortie extensions for when you don't want to use the extended ones (I haven't made the shorty extensions yet, I may not bother based on my first tests), those crazy extensions are probably staying for good now.
I started talking about extending the AMA's a couple years ago, ordered the aluminum a yr ago , and finished them up last summer, but was reluctant to install them because I couldn't figure out how to do the mathematics (the flotation and heeling moment mathematics),
I still have no clue how to figure the math, but figured if I make them removable, I wouldn't be out much if the extensions didn't work.
I strongly doubt anyone else will bother with this crazy mod, you don't need to do it on a stock boat obviously.
FE
EDIT:
My reasoning behind the mod is if you look at Randy Smythes SewSew rig which has about the same floatation as our TI's (a little better L/W ratio though), and you look at his AMA's they likely have similar flotation to what we have on our TI's. I think I read somewhere he is running a sailset from an F18 (with the very top lopped off because it got ran over by a truck or something). I'm just guessin here but he is likely flying 500 sq ft of sail on a boat not too different from our TI's (flotationwise), look at the pic Keith posted, the stance on his boat is around 14 or 15 ft wide, I've seen some really fancy foiling tri's that are even wider. I can't do the math, but I figured why not try widening my boat and just see what happens.
Now I'm out looking for an F18 sail set that's been run over (just kidding).
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