Join Date: Dec 2008
Location: North Carolina
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Flattening Reefed Mainsail, or why no Cunningham?
It's my understanding that when one reefs the mainsail, generally, you would want the mainsail to be flat to depower the sail. On an unreefed, fully hoisted sail, most have a cringle at the mast for a cunningham to flatten the sail. But at/above the reef cringle at the luff end of sails, I have never seen a cringle for a cunningham. Since all sails have a fullness or belly (i.e. the sail is not a flat piece of cloth and is designed to somewhat be similar to the upper, curved surface of a wing), this fullness area is greater in the reef cringle areas than it is at the foot of the fully hoisted sail. Thus, it seems (and on my boat) hard to flatten the reefed sail. Why are there no cunningham cringles above the reefing cringles?
I use a single line reefing system. As originally set up by the dealer, when reefed, the bottom of the sail would pull away from the mast, aggravating the flatness issue. I installed two additional sail slides and connected them to the luff end reefing cringle with a large shackle. Now when reefed, the luff end stays snug to the mast, but the sail is still not flat. On the leech end of the sail, the bitter end reefing line is around the boom and through a small cringle at the foot of the sail, and tied off there. The reefing line then goes up vertically (perpendicular to the boom) to the leech end reef cringle, through a block and back down and aft to the end of the boom, inside the boom forward to the luff cringle. You can tighten the reef line as tight as you wish and the sail is not flat. As I explained above, the sail is snug to the mast. The leech end can go be pulled tight towards the end of the boom, but once the leech reefing cringle is at the boom level, the line is pulling against the boom and the end of the sail will not/cannot move aft to flatten the sail.
I know many will say you need a two line jiffy reef, but with the way that the reef line attaches to the boom at the outer cringle, I don't see whether it makes any difference whether it's a two line reef or a single line reef. My situation would be helped a good bit if I could tighten the boom vang and mainsheet to pull the outer end of the boom lower. However, everything is a compromise, and the bimini, which I must use to avoid sunburn, is at the right height, but too high to allow much lowering of the boom end to flatten the sail that way. Any thoughts? Thanks.
Last edited by NCC320; 11-14-2010 at 12:54 PM.