Shaft Cladding – Welding Heat will Cause a Bend

We were recently approached by a captain from a 112 foot Westport who we have done business with in the past. The boat was purchased by a new owner when an engine vibration was uncovered and the captain asked us to check the shaft and alignment to remedy the problem.

One of the first steps our technicians at High Seas Yacht Service took was to remove the shaft to check for potential problems such as a bend or bad coupling fit. Once the shaft was removed, it was sent to our machine shop – Straight Line Marine. On the straightening table we found that that the run-out showed that the shaft was .001” or within straight tolerance – obviously not the cause of the vibration.

However, what we did find was some fairly significant pitting around the Tide Marine Lip Seal that was causing the seal to leak.

Cladding process

Given the pitting on the shaft and the resulting leaks, we recommended a procedure called shaft weld-over or cladding, a process of repairing a worn or damaged area on a shaft through the use of welding and a lathe. Our machine shop is ABS Certified for Aquamet Stainless Steel Shaft Cladding and was the first machine shop in Florida to hold this designation.

For this particularly job, we welded an area approximately 3 inches long or 10 minutes of continuous welding to address the issue. Welding of this intensity can generate extreme heat of up to 700 degrees Fahrenheit. This type of heat can cause the shaft to bend so after a cooling off period, we re-checked this shaft and found that it indeed had a bend of 0.020” at the coupling end. After putting the shaft through the straightening process and returning it to 0.001″, it was ready to be re-installed in the vessel.

Finished shaft

The lessons learned from this particularly job – when investigating the cause of one problem, another may come to light. Finding the pitting and corrosion on the shaft that was causing the leaks was the result of good diagnostic practices, delivering a solution that saved the captain thousands of dollars by cladding a shaft instead of replacing it was possible due to the combined experience and expertise you get from High Seas Yacht Service and its sister company, Straight Line Marine. The lesson also reconfirmed that cladding does cause a bend – so make sure the machine shop that performs this type of welding is qualified to straighten shafts.