Mast Paint Flaking Off - What's Below It?

[Sean Engle]

A question:

My boat has a few places on the mast where the paint is "bubbling up" - that is, the paint has sort of blistered up, and is/can flake away.

One of the places this is happening is down below, near the cabin sole. I assume this is from water running down the inside of the mast - but what concerns me is that behind the paint there is a chalk like substance that I can pick away at - what is that stuff? The mast is aluminum - so it's not supposed to be corroding.... What is that stuff - and can I just sand it down and paint it - or is there cause for real concern?

Thanks,

 

[Geoff Johnson]

I have that at the very bottom of my mast (1985 32-3) I assume that there is some corrosion due to perhaps an electric potential between the mast and the step (as there is around SS fittings). I am hoping to have my mast Awlgripped next winter, if I can afford it.

 

[Sean Engle]

Have you had a rigger look at it? Mine is in spots around the base - perhaps 2" here and 2" there... It's on both sides though - enough to worry me...

Thanks,

 

[Geoff Johnson]

Not specifically, although the mast has been removed a couple of times (once to change the standing rigging). The yard does a good job of pointing out defects and has never mentioned this. Have you suffered metal loss/thinning or is it just a white powder on the surface where the point used to be? If the latter, I wouldn't worry about it.

 

[Sean Engle]

It's white powder - but it seems very chalky. I'm sure it's probably ok. I'll have a rigger look at it sometime soon.... I just need to add it to the list of things I need to have done....

Thanks!