Shaft Crevice Corrosion – Not Good for Tide Lip Seals

Crevice Corrosion on Shafts will Destroy a Lip Seal System

While working on a complete running gear service for a new owner on a 103′ Cheoy Lee we came across a few items that needed repair.  One item was extensive crevice corrosion on the stainless steel propeller shafts.  Crevice corrosion occurs when a vessel sits too long in still water.  It is most often found in the cutlass bearing, seal or exit tube area where water is not flowing.   Crevice corrosion is most problematic in the Tide Seal (Lipseal) area since the seal requires a tight fit on a smooth turning shaft surface.  The pitting in the corroded area immediately leaks and damages the seal.

Fortunately, a crevice corrosion repair is possible using shaft weld-over techniques.  Weld-overs require specific training and skills.  The final product when done correctly is a clean, perfect shaft surface.   Compared to replacing a shaft this is a very economical repair.

A weld-over generates a lot of heat and tends to bend the shaft.  This means a shaft straightening is almost always required.  Of course, with the shafts out of the boat a check with the optical scope on the strut alignments and an overall engine alignment check is always part of the plan.