Painted mast corrosion ...

[Scott T-Bird]

I was a little dismayed when I took my mast down this year and discovered some corrosion under the port spreader. With the difficulty of removing SS rivets, I didn't remove SS components that were on the mast such as this spreader ear. However, other than this area, I had no other locations that were troublesome. This is 6 years after painting the mast with 2-part primer and 2-part Interlux Perfection. My first step was the Interlux 353 Prime Wash Base (self-etching primer).

The Stbd side had no problems at the same location. I'm wondering if I missed that spot with the Prime Wash, or if it had more to do with SS contact to aluminum.

BTW, I've tried to drill out these rivets and I'm not getting anywhere.

I've decided to do a small temporary repair this year and a longer term solution if I see it come back too readily.

 

[tommays]

They look like 3/16 rivets ?

You need a 135 degree split point drill and I prefer the stuby ones

A good quality American black oxide will go right through and I use a low RPM pulse of a few seconds to stop and heat and work hardening issues

When I put mine back together I used UHMW tape on all the stainless parts were they mad contact and this cut down on any reactions

 

[THECUSCUS]

Scott, two ideas to help, if disimiliar metals was the cause of the corrosion. Use a layer of black electical tape between the black and the mast (might not be as critical for yours, since the mast is painted). Put some blue Loctite on the rivets before you insert them. Just two simple things to help cut down the corrosion possibility.

 

[Eddie7045]

Being that this only happened in this one area, I would

suspect that you were on to something in regard to missing a spot during the prep work. Along with that would be condensation forming directly beneath the fitting contributing to the corrosion by constantly bathing the vulnerable area. Salt crystals in ocean air dissolve into the condensation making a solution that is lethal to metal. I would carefully strip and prep the affected area making sure that it is not only clean but bone dry as well before each coat and while each coat cures.