Cutless bearing life

[Tranona]

I'm leaning towards barnacles .There's a lot of them here and they're quite abrasive.The Aquadrive is in good shape and the shaft the same.The P bracket is not loose and the bearings are usually bought from Trafalgar Yacht Services .
The water flow could be an issue.I have a rope cutter that is mounted by necessity only a few mm away from the P bracket.Maby that's not enough for a good water flow.

You need about 12mm for good water flow out of the bearing. Doubt that wear is caused by marine growth if the boat is used regularly. Can happen if a boat is left static for long periods in areas of high fouling, and can also lead to crevice corrosion if it stops water flow completely.

Perhaps you can post a photo of your stern gear.

 

[Neil_Y]

Water flow.
3.00mm is sufficient for water to exit/enter the bearing for lubrication and cooling. ( sorry to disagree with you Tranoma but we haven't seen any accelerated wear with these specs, many being commercial vessels) Pilot boats used as pusher tugs create huge shaft vibrations and forward loads which will put bearings under high loads and reduce P bracket to prop gaps.

This is as a bearing supplier specifying clearances for rope cutter fixings.
Cooling is the most important factor especialy with any bearing materials that are melting as they will soften as they get warmer.

Marine growth.
Small crustacean are very abrasive as others have said, that's why the latest Maritex bearings have a surface chemistry that resists marine growth. A particular problem in warmer waters.

Rapid wear will be one of the suggestions already mentioned, is the shaft worn at the bearing? what is the starting clearance on the new bearing? There are many variables to consider.

 

[30boat]

You need about 12mm for good water flow out of the bearing. Doubt that wear is caused by marine growth if the boat is used regularly. Can happen if a boat is left static for long periods in areas of high fouling, and can also lead to crevice corrosion if it stops water flow completely.

Perhaps you can post a photo of your stern gear.

I'll post a picture soon.