bulkhead hole in js ski will need to be enlarged to fit. I used a 60mm step bit and slowly removed material until the bearing mounted flush to the bulkhead. before installing bearing holder, I waxed the bearing holder and smeared 3M 5200 inside the hole to ensure no water infiltration into hull then bolted down bearing holder and let 5200 cure. after 5200 cures, remove bearing holder and wash off wax. then install bearing holder with some 3M 4200 between bearing holder and bulkhead.