For many years I used a mainsail with a deep shelf foot and flattening reef for racing as well as cruising, and, after loose footed mainsails became popular, that mainsail was just as competitive against them as it had been before. The deep shelf foot of that sail enabled me to adjust the draft of the mainsail drastically, to optimize the boat's performance at different windspeeds. The flattening reef enabled me to take the belly out of that sail when I wanted the boat to point to windward. So, I'm not convinced that a loose footed mainsail is inherently superior to a footed mainsail with a racing shelf foot, but that's not the only reason why you should get a loose footed mainsail when you replace your present mainsail.
When you ease the outhaul of a footed mainsail, the boltrope, which attaches the foot to the boom, prevents the sail from taking on a really deep draft. When you ease the outhaul of a loose footed mainsail, it can take on a much deeper draft, similar to what was possible with the old style racing shelf foot. That means your loose footed mainsail will be capable of a wider range of adjustment than the ordinary, footed mainsail, and that's a huge benefit. The loose footed mainsail is capable of about the same range of adjustment as the old racing shelf foot.
A lot of people set the tension on their outhaul and never adjust it again for the rest of the season. If you get a loose footed mainsail, you should definitely install a couple of blocks and a cleat on the boom to enable you to quickly and easily adjust the outhaul tension while under way, because that easy adjustability is what enables you to take advantage of the loose footed sail's benefits. Then try adjusting it with more draft at lower boat speeds and windspeeds and when sailing off the wind, and with less draft at higher speeds, and when sailing to windward.
I just ordered a new mainsail and genoa for my boat, and had no reservations about going with the loose footed mainsail (but I did specify that I wanted the performance cut). ;>)
Last edited by Sailormon6; 11-08-2006 at 01:45 PM.