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Today there was a most important convergence: It was not raining, and I was home while it was light. So I took another look at the mast boot.

Having given up on everything else, I cut a new one. Because I had the old one, I didn't have to go thru the patterning exercise - I just traced the old one onto the Naugahyde and cut it out. But first, of course, I had to pull the old one. It was instructive.

Here's the inside of the old one, showing clearly where water had been coming in. (Because of the way I laid it out in the cockpit, that's the bottom of the boot at the top of the picture.)  There are a couple of (dried) streams to the left in the picture, and one gigantic wet stream to the right of center in the picture.  When it was installed, this was at the back, where the sail track is on the mast - a tough place to seal.

The smoking gun

And look what I saw when I turned up the edge and looked closely at the boot where it went over the track.  Yep, the vinyl coating on the fabric had cracked, twice.

Some interesting gel-life growing inside the old boot

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Update:

Looks like someone is running a hose
on the deck above, doesn't it?

And wouldn't you know?  Mother Nature delivers a test storm not long after I get the new boot installed.  Perfect timing... and it's not just any storm - in fact it is a deluge of Biblical proportions - any minute now I expect to see pairs of animals lining  up out there on the dock.  It's been going on now for 24 hours, and there is no end in sight.

So far?  One drop. 

Yeah.

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Update #2:

Sunny and dry today (but cold).  This allowed me to inspect the new mast boot more closely than I was able to during and immediately after installation.  What I found was incomplete adhesion of the polysulphide I had used to seal the seam where the ends overlapped on the boot.

Drop explained.

And fixed.  (Replaced the polysulphide with 3M 5200.)

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