Has anyone ever installed a self-tacker on a curved beam? Any info greatly appreciated. It doesn't look that difficult but once you drill you can't change your mind. Thanks to Trey I have acquired one from an I-20. My current thought is to have the center of the curve rest on the crossbar and position the legs to support/strengthen the outer edges of the track. How would you install it?
The intention of that particular self tacker is for it to be able to pivot and align itself with the sheet loads. The original Nacra self tacker on the I20 was a molded fiberglass fitting that riveted to the main beam, but because it wasn't able to align itself to the loads it often cracked because of misalignment. In order for that self tacker you have to pivot, all of the pins that hold it to the beam must be in a straight line - otherwise, it will not move once you pin it in place.
I might consider first mounting the self tacker to a straight piece of aluminum angle or tubing and then mount that tubing to the beam...but it would still be tricky. You could cut and bend the ends of the angle to give a mating surface...attach on the bottom on both ends and on the leading face in the middle.
Boy you are sure getting agressive with this Hobie 18! I like to see the innovation you are willing to commit to. You have been treading in a lot of untested waters and still you go on. My applause to you.
As for the self tacker for the jib. It has to be at the same arc as the clew of the jib. So...while the jib is up on the forstay take the clew in your hand and swing it to a fro. Make very exaggerated movements and imagine the the jib has to go way out. You will see the arc angle that you have to pay attention to by doing this. Okay that is the way to figure out the arc you need and the angle that you can mount the track.
I hope you get lucky and find that there is little modification you have to do to the Fiberglass part, if that is the one you got. I am sure you will have to either cut some out of the middle or add some as you go toward the ends.
One thing you could think about is to mount the middle of the track where you think it should go. Then very gently move the traveller car with the jib attached back and forth to make sure you have the right angle to the jib. When this is right then you can attack the ends with spacers of appropriate length for the rest of the track and secure tightly. After all is well then some foam for shaping and glass for a finished product to make it look as though it belonged there in the first place.
We have moved on now, but the very first Blade F16's (australia) used a 49-er track as well. All the Blades still use two glass pilons to hold the track. If you design them robust enough then they will hold and not crack. Both pilons are at the end of the curved track. This setup works especially when the track is relatively short. If you use the 49-er track then that rail is of the I-track type and no modification to the track is needed. If you really want to use the much less tall recirculating ball tracks (I dislike them with a passion) then you will have to bend a piece of rectangular Alu tube and fit the track to that. This footing will make the track strong enough to handle the loads when it is only supported at the ends. But I-track is best, simple, cheap and won't jam with sand or dirt.
I think the earlier nacra glass track base was a little to much engineered to low weight. If you have a round beam then a two pilon setup may well be an advantagious one. You do have to align these well with the arc of the jib though.
I have the new aluminum one from an '06 I-20. Has 6 feet, I believe. They are adjustable. I assume the pressure/pull is at the ends and the center self sustaining due to the curve. It appears I need to get a jib first and then set the tacker up. Anyone got a used F18 jib?
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