Trailering, even a short distance, heats the hubs. When the wheels are submerged during launching, the hubs suddenly cool and the air inside the unprotected hubs contracts, forming a vacuum, which draws in water through the rear seals. There is no such thing as a rotating seal that stays perfect. Water and grit thus drawn into the hubs relentlessly destroy bearings. When properly installed and maintained, Bearing Buddy prevents wheel-bearing failure and eliminates bearing repacking. Boat trailer wheels can be completely submerged.