"Hey there,
My two cent'
"Hey there,
My two cent's worth...
Most waterproof greases that are rated for wheel bearings are good. Each person has different useage tho.
Few pointers:
1) Check and adj bearings on an annual basis. Water tends to creep in everwhere...
2) Re-pack the bearing when this inspection is done. If bearing is in good cond, wash with cleaner, rinse and dry before applying fresh grease. Ensure that all exposed steel areas and cap has layer of grease. Do not over-grease the hub, grease will pop out the seal from heat expansion.
3) Always try to ensure that hubs are cold before launching the boat. If the hubs are hot, the cold water will cause the grease to contract and potentially draw water in as the air pocket in hub shrinks.
4) On the grease cap, use a good silicon type of sealer to prevent water from getting in. As most caps are press fitted, a fine hairline gap may be present to allow water in. Remember, the trailer drops into the water by a few feet, water pressure will cause ingress.
Regards!
Benjamin."