The following part numbers are for the bearings used in the Accusteer WaveBlaster steering system. If you can, pay the difference for some Chinese Stainless bearings. With these bearings the cases are stainless and you can reduce the concerns about rusting of the bearing cases which will cause discoloring in the hull and the headache to clean and replace a rusty bearing.
Qty 2: R12-2RS [Dimensions: 3/4 x 1-5/8 x 7/16]
http://cgi.ebay.com/SSR12-2RS-Stainless-Steel-Bearings-3-4-x-1-5-8-R12-RS_W0QQitemZ260194630463QQihZ016QQcategoryZ31485QQcmdZViewItemQQ_trksidZp1713.m153.l1262