Cracks in tower mounting plates...What should I do?

[barefootinjimmy]

A few years ago I had the cracks in my 2005 SAN rear tower mounting plates welded.
Now the rear starboard tower mounting plate cracks have returned just beyond the welds.

What is the best way to fix these once and for all?

I have been told to use a thicker plate, but I am concerned it might be difficult to align the new thicker plate to the surface of the boat.

Any suggestions?

[BrickBrock]

Jimmy, please post photos of the cracks.

[Tryathlete]

Pics are a great call. If your tower is FCT 1, Gen 2 with flat mounting plates (guess), assume the weld is failing on the plate edge and not on the round tube portion of the weld. If that's the case. A heavier plate will help. Don't worry about alignment--additional thickness is not going to do anything as far as alignment goes. As a matter of fact, I would even cut 1/2" off of the tube to get away from the heat affect zone of the old, failed weld. It helps to have this weld performed by a skilled welder because aluminum is not as simple or robust to weld as other materials. You'll need lots of good shielding gas, proper feed material and a good TIG welding setup. Most of all you need a skilled welder.

I personally like the spherical cap ends and threaded 3/4-10 hollow studs on Gen 3 towers that fit into a CNC cup/base on the gunnel. The stress distribution is way more uniform than those base plates, but going to a thicker plate, getting to fresh, non-HAZ tube and welding properly should get you where you want to be.


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[Tryathlete]

Pics if you can. Might change the answer


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[barefootinjimmy]

To Make a long story short. I replaced the rear 1/8 inch mounting plates with harder thicker (5/16") mounting plates. No more problems.