Crack at mast base

[medvinden]

Today I discovered a crack at the foot of my mast. It showed after I had removed the mast base to install a cable canal. I don't know if the crack is new or old. The aluminium mast is 40 years old and keel stepped. The crack is 14 cm (around 6 inches?)
Is it possible to TIG weld the crack in order to get a sufficient repair? Other suggestions? I'm not that keen on buying a new mast...

[chris95040]

One thing to put your mind at ease, the base of a mast ends up being crazy overbuilt for the compressive loads it takes- the dimensions of the mast give it the stiffness it needs to avoid buckling up higher, and this results in a base that is typically way stronger than necessary. I'm no expert and folks here will chime in with superior advice, but I bet simply drilling a small hole at the top of the crack to stop it from continuing would be adequate.

On the other hand, why did it crack to begin with?

[medvinden]

Well, there is a possibility that the crack was born when I or some previous owner opened up the mast by removing the mast base (mast foot?). Some mild violence was required, and even though carefulness has been applied, you can't be sure how 40 year old materials react to that.

I have been given the advice NOT to weld it, because it would have a potential to introduce (new) weak spots in the aluminium. Instead I have drilled a hole at the end of the crack, attached an aluminium plate (with rivets) around the damaged part, and secured it with some long hose clamps.

Coming winter I plan to take the mast down again (it's common routine here in Sweden, when boats are stored on the hard) and make a more permanent repair, consisting of a thicker 316 plate, which will be riveted to the aluminium around the entire mast profile. That should hopefully add the necessary strength.