[quote=Edchris177]The wishbone is a mast rotation device, it was optional on the boomless models. Murrays sells the part, $39
[img]http://www.murrays.com/mm5/graphics/00000001/25-304.jpg[/img]
You may be able to find a used one from a parts boat, email Dan berger, he usually has lots of stuff for sale in the classified section, & is a good guy to work with. You can also ask for the cleats to mount to the front beam.
Nacra says on boomless boat the rotator is to induce rotation. I've never raced, so I'm not knowledgeable about getting every last speck of speed, but the rotation certainly does help. If you ever forget about it & have it on the wrong side, you suddenly find yourself flat on the water when all your instincts say you should be flying. The photo above is old, I don't have it rigged like that, one of the guys here,(Philip, or Ron B?)told me to tie a line to the eye strap on the beam,(just inside the cleats)then out to the end of the rotator, then back through the cleat. This gives a 2:1, & you need it. I was surprised how much force there is trying to turn the mast. In very light air I cleat both sides, it prevents the mast from banging to & fro & shaking the wind out of the sail.
[quote]The bottom of my mast looks like yours in the pic, except it doesn't have the sides cut out, or any holes for pins. Likewise, the ball looks larger than that, and doesn't sit anywhere near that far in the hole. About half the ball is captured under the bottom of that necked part of the boom.[/quote]
Does it look like this?
[img]http://www.thebeachcats.com/gallery2/main.php?g2_view=core.DownloadItem&g2_itemId=72515&g2_serialNumber=4&g2_GALLERYSID=d49983b083fec5dafcac9c38edd24491[/img]
This from G Amicks boat, a 5.2 that he resurrected, he has lots of pic, look in members albums, scroll down to Amick, he did a fabulous job.
Dave, I'm pretty sure he has the old style non captive base. With the ball only 1/2 in there is no way to drill & insert a pin that would hold anything. Mine is the 1 1/2" newer system. It is hard to tell size from the photo, I should have put a tape measure up against it.
Measure your ball, but be sure to measure from side to side. The ball will wear on the top where the mast works against it, the top may look a bit flattened & top to bottom measurement won't give you an accurate picture. Dave is right, the rig tension keeps the mast in place when capsized. The advantage to the newer captive system is it prevents the mast from jumping off the ball when raising or lowering. I don't know what oyur budget is, but if Dan B doesn't have a new style base for sale, Murrays sells the whole conversion kit, part 01-8002 for $160
<!-- editby --><em>edited by: Edchris177, Sep 14, 2010 - 01:15 PM</em><!-- end editby --> [/quote]
