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.
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
