Persistence

Persistence pays off in the end, if you don't give up too early.  This is one of those cases...

Remember this post?  In it I talked about using aluminum tape to seal the top of the mast boot to the mast proper...

When it was new

Backspacing at least 10 years, we have been dealing with intermittent leaks at the mast partners.  Each thing that we have done has improved the situation... but the leaks, tho diminishing in quantity and in frequency, have persisted.  Replacing the mast boot, resealing the deck ring, and finally replacing the deck ring altogether with a composite material that won't absorb moisture and consequently change shape and break the seal have all helped.  But even after all this, there was still the occasional drip coming down the mast in heavy rain and wind. (OK, maybe I am a little anal retentive here...)

Looking up from inside revealed that the water was not coming in at deck level - hooray!  That leak is stopped!  Instead it was coming from higher up.  The only place where it could be originating was at the seal between the top of the mast boot and the mast.  However, a brief inspection (because it was raining) did not disclose any flaw there.

But.  The water simply had to be coming in there.  So I pulled the hose clamp off to get a closer look at things.  Lo and behold, the aluminum tape was just plain gone under the hose clamp!  Galvanic corrosion between the stainless in the hose clamp and the aluminum tape ate the tape, and created an opening for rain to find its way in. 

There are two lessons here.  First, galvanic corrosion is evil.  And just as importantly, frequently corrosion is hidden.  Both very much worth remembering.

The fix was easy:  remove the offending hose clamp (it really was overkill anyway - the aluminum tape is more than sufficient to hold the boot up), and apply a fresh layer of aluminum tape.

Persistence