I have just purchased a new mast hinge and bearingand disk set. On the casting that the bolt turns into to hold the bearing on, is the bolt supposed to show threads if th ebearing is not on. I'm not sure if i have a lot of corrosion around the bolt or if that is part of the casting.
Also where does the little disk go? does it actually go up inside the mast hinge? or under the bearing?
Dave
The disk (a hobie 16 mast bearing chip with a hole punched in it) goes under the bearing.
Not sure what you mean about the bolt showing threads... The bolt should tighten up without tightening up the bearing. The bolt/screw should bottom out before the head pinches the bearing down in any way to prevent it from turning. The bearing should float on the disk and rotate with the mast. That help?
If you tighten the bolt and it prevents the bearing/chip combo from freely rotating then install the bearing without the chip. The new 18's come without the chip (according to my Hobie dealer). The chip is included as a spacer for older boats or boats that have the dolphin striker post adjusted differently.
I installed without the chip on my '89 Hobie 18. With the chip the bearing wouldn't turn at all.
-Todd
TheMightyHobie18 in MN - Sailing season over. 28F tonight 
thanks
Just wondering about the casting that sits on the front cross bar? If you turn the bolt out would it be flat?
Todd,
The water's still soft, what are you complaining about? Put on your wetsuit, and get out there man!!!
Tim
If I want to extend the season I have to buy 2 dry suits. One for me and one for whoever else I can convince to come out when there is frost on the pumpkins.
I wouldn't want to impose on you and your brother again... The help is still appreciated.
Dave, I'll check the casting when I get home. I think it's flat but I don't remember for sure.
-Todd
Todd,
You only need one drysuit, I've already got one, and am probably crazy enough to sail with you when there's frost on the pumpkins!
Tim