Another way to go, oil bath. I trailer a 27 ft orca over 1000miles one way and no longer have any problems. Change oil once a season, haven't touched a bearing in three years, used to have replace bearings every season, despite use of good grease and bearing buddies. Ranger bass boats all come now with oil bath bearings. Trucks have used it for many years. Company I deal with is:
Liqua-Lube Inc.
PO Box 71
621 East Lake Street
Lake Mills, WI 53551 USA
Phone 920 648 5188
They are great to deal with, and have various sizes. Its a great system.