Dacron Mainsail Rot

[maxingout]

How long sails last on an offshore yacht depends on many things. If you carry large amounts of sail in high winds, you may actually blow out your sails. That obviously is a greater risk with lighter sails than it is with the heavy nine ounce mainsail found on Exit Only. We never blew out a sail during our circumnavigation. Now that more people are going to roller furling mainsails that may not be as heavy, blown out mainsails may be more of a problem.

Chafe is a great sail destroyer. For those who sail wing and wing downwind, you need to have chafe patches on your mainsail to protect it where it may rub against aft swept spreaders. On Exit Only, our cap shrouds were an obstacle to running wing and wing - you couldn't get the boom far out without the sail chafing against the cap shrouds. It would take large chafe patches to protect the mainsail against cap shroud chafe. Because of this problem, we rarely ran wing and wing. Instead we used a double headsail for running downwind, and we did not raise the main.

Chafe and blown out sails were never a problem on Exit Only. Dacron sail rot was our biggest enemy. After eleven years, our mainsail started to fall apart from rot. The stitching along the seams never was a problem. The dacron fabric itself began to disintegrate starting about 1 meter from the leach. That was the part of the sail that was continually exposed to ultraviolet radiation when the mainsail was uncovered and lying in the lazy jacks with the sail down. It's a fact of the cruising life, that the mainsail is often down for significant periods of time, and it's not appropriate or convenient to immediately place the sailcovers on the boom. The result is that the leach of the sail gets more UV light than the rest of the mainsail. After eleven years, the leach area began to disintegrate. Vertical slit like tears along the fabric weave began to emerge in the sail. I applied patches to cover the tear, and the dacron fabric would tear along the edge of the patch. I tried patching the tears with contact cement and new dacron, and when I rubbed the patch in place, a new tear would instantly appear adjacent to the patch. By the time we arrived in the Med on our eleven year circumnavigation, the mainsail was finished.
The rest of the mainsail appeared strong.

In contrast, the genoas on board Exit Only survived without dacron rot. They had covers sewn along the leach so they didn't have ultraviolet exposure to the leach as much as the mainsail.

Probably if we had immediately covered the mainsail every time we dropped it, our mainsail would still alive and well. We probably would have gone crazy putting the mainsail cover on and off a bazillion times in 11 years.

A nine ounce dacron mainsail that lasts eleven years is good service for a sail on an offshore catamaran. By that time, the sail material is stretched out as well, and most people would like to have a flatter mainsail unless they spent their time running downwind in the trades where it doesn't matter so much.

How long have your sails lasted before you had dacron rot?

[Joli]

Since we live in Ohio with a very limited season we can go a loooong time, unless we are racing then 3 years or so.

11 years for your main is very good service, you must have covered it more then you realize.

[barnakiel]

Our sails are 8 y.o. now and we only got damage in stress areas. However, judging from the type of damage it is from UV. Call it an aggregated stress/UV damage.

We had them up for about 500 full sailing days, mostly tropics, the rest of the time under Sunbrella covers.

Dimension Polyant cloth, polyester, plain.

b.

[maxingout]

Originally Posted by Joli

Since we live in Ohio with a very limited season we can go a loooong time, unless we are racing then 3 years or so.

11 years for your main is very good service, you must have covered it more then you realize.

I am not sure how well we did in covering our mainsail. I can definitely say that not covering the mainsail was the main source of boat guilt during our circumnavigation. Whenever I didn't do it promptly, I felt guilty. I knew better,and I could have done better.