mactech's valueProject Description
A major Great Lakes ship construction and repair operation needed to convert a ship’s stern tube bearing lube system from oil to water cooled. To accomplish this we shortened the 10” thick stern tube by 5 ¾”, faced off the end of the stern tube, and bored ¾” of material out of the stern.

Mactech’s Value Added to the Project
Mactech was contracted to work on the project based on quality, timely, and on-time work done in the past. Mactech had a solid understanding of the job in place and what the customer was trying to accomplish.


1. Set-up 6″ bore bar and rough bored 3/4″ x 44″ of material out of stern tube
2. Welded a 3/4″ x 6″ x 36″ diameter rolled ring to end of stern tube
3. Mounted Mactech’s 843 Clamshell onto rolled ring and severed 5 3/4″ off end of 10″ thick stern tube.
4. Re set-up 6″ bore bar with facing attachment and machined a weld prep groove on end of stern tube for weld repairing a crack.
5. Faced end of stern tube perpendicular to centerline of tube
6. Finish bore ID of stern tube

Equipment Used
To go about this project we custom built sever blades that were made to be used with the 843 Clamshell to sever 10″ wall stern tube as well as a 6″ x 8′ bore bar with facing attachment.

The repower was completed on time and within the budget.
The customer is very happy with new water cooled lube system.