Monday, November 20, 2017

Ever Wonder What Happens with Laminate Sails When They Get Old?

Like us, they just fall apart.

In its defense, this sail is 1996, and until it's last day maintained perfect shape and would go to windward like a banshee. It was, however, showing signs of delamination. When going to windward, if you pinched up the inside lay we would often bubble to windward in spots, demonstrating the pressure differential between one side and the other. About 80% of the sail overall was disconnected, one side from the other. Only the sewn seams ever 2 feet were holding the the taffeta and Kevlar in alignment. The UV cover (polyester--not Sunbrella) could be torn between the fingers more easily than office paper.

Then one fateful fall day, with gusts topping 40 knots, the upper portion of the leach was blown open just a littl. The delaminated sail ballooned, air driven between the layers, followed by more delamination, and tearing. Within an hour there wasn't anything left worth repairing. Actually, there really wasn't anything worth repairing before the damaged.

Interestingly, the furler line did not slip, the sheets were around the sail several times. In fact, the sail had actually furled itself an additional turn, leaving some slack in the furler line. Weird.

 Only the top portion unrolled at all, and only a little bit. The delamination and the tear ran during the lowering process, which took less than two minutes and did not include flogging (I maintained sheet tension).

The fabric is polyester tafeta on both sides with Mylar and Kevlar strings bonded inside. Once the glue starts to go, the Mylar and Kevlar just float around inside. Once something starts  tear, it's over in a hurry. In yet the leach did not tear and none of the Kevlar actually failed.
But everything disconnected from everything and there is nothing left to glue, sew, or patch.

I'm sure modern laminates are better. I know this one was ancient. And yet, I have a certain fondness for polyester.

We'll see. However, what remains of this isn't even suitable for making into totes.

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