I guess one of the reasons for brand new sails to outperform older are
all the wrinkles. (Shape is even more important).

So, I tried on a small surface of a woven dacron sail. First, I marked
a rectangle about 200x300 mm and measured the eaxct size all
directions.

Then I used a household stem iron, set for polyester temperaure. ALL
wrinkles was eliminated and the cloth looked like brand new.

After its cooling down, I again measured the reference rectangle, and
it was the same size within fractions of a mm.

What confuses me a bit is that the sailcloth makers and sailmakers I
have asked for advice, all say that they do not recommend ironing
sails, but NONE of them has been able to present ANY piece of fact
about why. I have asked if the cloth would shrink, swell or stay the
same by ironing - no answer. At the final stage of clothmaking, heat
is used to strengthen the cloth.

Does anyone out there have any facts in this field that I need to know
about?

/Eric