Joe wrote:

In a storm would you, if you had a ketch:

1. reef down the main and mizzen, drop the jib.
2. use just a tri sail on the main mast.
3. use a storm jib and a reefed mizzen.
4. just use a storm jib.
5. Use just a reefed main
6. Use a reefed main and a storm jib.

Depends on the rig, depends on the conditions. Usually a mizzen that is
made for everyday sailing is not going to be tough enough to stand up to
use as a storm sail, reefed & used together with a jib.

But, being able to drop the main and sail under jib & mizzen as wind
increases is a good characteristic. Not all ketches will do it well.





And why is a tri sail track offset on the main mast?

Is it just because you can raise the sail fast without un-bending the
main, or does it have something to do with shape.

So that you can bend on the trysail before the storm, and keep sailing
with the regular main until you need to douse it. In storm conditions,
trying to unbend the mainsail and thread in the trysail is going to lead
to loss of crew or loss of sail at least.




How much, if any foil shape should a tri sail have?

Very little. It does need some camber, but not much. Probably a web site
that says, but I'd guess less than 10%, possibly around 5%.



And how do you best figure what size tri sail you should use?

Scaled to the boats displacement, righting moment, & lateral area.



And with a quick double reefing system, do you think a tri sail is
needed?

Yes. The trysail, or storm staysail, is for conditions that are worse than
you want your regular sails flying in.

Once I experimented with using a small boat's jib as a storm staysail. It
set nicely and was about the right area (60 SqFt on a 30' keel boat) but
shredded after about an hour in 40 ~ 50 knot winds.

Fresh Breezes- Doug King