I was perusing a Sailworks rigging manual and found the following which I didn't know about. Like most of you I just snugged it up to get it out of the way.
7. TACK STRAP
The tack strap at the foot of the sail
should be looped around the lower
edge of the mast base. This strap
is used to increase the tension that
runs along the foot edge of the sail
and makes the foot area deeper.
The tack strap is particularly useful
for improving rig control when very
overpowered. In these
circumstances, use lots of tension
on the tack strap to increase the
depth and tension in the lower half of the sail. This
increases the disparity of rig tension between the upper
and lower sections, effectively increasing sail twist, which
improves rig control by lowering the center of effort.
And I thought it was just there to prevent the sail from unwrapping after you roll it ..... darn ...
Seriously though - on one of my sails it also said the lower tension added to upwind capabilities ....
Albert
Don't beleive any of it. The stuff written in sail manuals is worse than wrong. I remember that for years I used to clean and dry my sails before rolling them up. This was all in accordance with the owners manual. I saw a post on rec.windsurfing from the sail makers mother (she sailed to) saying it was a waste of time to dry out your sails. I sent her an email asking why they put the recommendation to do so in their manual. Her resposne - I didn't know we had that in there....
So, the tack strap is really just for decoration.
I you have one feel free to cut if off with a knife. Its kind of one of those useless thingies like the big screw you see on the deck of some boards (you know -the one with an o-ring underneath it). I just remove em, so they won't come flying off when I'm sailing. 
What happens in a black hole stays in a black hole.
You're Amazing Randy... oh wait, that's not right. You're Insane Randy. :shock:
I was gonna buy that cool looking JP board of yours (the one with the missing vent screw) but then a little bird told me how you take care of your stuff: "Fin screws?! I don't need no stinkin' fin screws, just Superglue it in!"
Cheers
Chris,
I never could get the vent screw out of the JP. So I painted it black to make it look like it was missing. You're safe. Trust me......
What happens in a black hole stays in a black hole.
Funny thing - reminds me of the days of negative outhaul. For those of you who've not rigged a sail built in mid-late 90s, a lot of sail makers designed the sails to have a lot of tension but let the wind pressure create the depth in the sail. You'd rig the sail so that the boom actually curled the sail in a couple of cm. When the sail powered up, the sail would pull forward and create the desired shape.
I saw more than a few people rig those sails with positive outhaul. I'm sure they saw the grommet there and figured, "heck, there's a grommet for an outhaul. I guess I should give it a good pull." The sail would end up way too flat and they'd complain what a POS it was. When you'd try to be helpful and suggest that they not only quit pulling outhaul but actually push the boom in a couple of inches they'd smile and tell you to go ... yourself.
Fun times....
I'm sure I meant that in the kindest possible way. Dude, don't tell me how to rig my POS gear.
At a regatta once, Gebi did a rigging clinic to show how neg outhaul makes sense. He explained that the "internal tension" held the shape. We locked onto that instantly... relating everything to Internal Tension. Bad start, bad finish, bad attitude, good attitude, overpowered, underpowered, traffic jam, broken heart, fear & loathing, PMS, etc... all caused by–
>>>Internal :shock: Tension<<<.