The cunningham is esentially a rule cheater. It provides a way to
increase luff tension without pulling the sail outside the black
bands.

"Capt. JG" wrote:
I guess if we're talking about racing...


Or a sail that is cut so it has no room to increase luff tension- for
example, if the head is at full hoist and the gooseneck is fixed. Luff
tension is luff tension. If you can't get it by pulling the top
tighter, then you have to pull the bottom... and if the bottom is
fixed, then you need a cunningham.

BTW a lot of new sails are made with the tack free to float up & down
as tension is adjusted.... not fixed to the gooseneck.

BTW 2 if you have a sail that need the cunningham pulled on in light
air, then that sail is blown (or the luff boltrope has shrunk).





How about boom brake or jibe-preventer? :-)

I'd consider that a "control line" but don't like them and have never
used them on a boat I was skippering. If you can't avoid gybing, or
keep control of the boom when gybing, then you need practice on the
helm & sheet!
OTOH for a long cruise with a windvane or autopilot, they are useful
but in the way.

They work great for any reasonable length of time... I wouldn't bother for
just a few minutes, but the preventer is easy to rig and unrig, and is worth
it in shifting wind.


So is PAYING ATTENTION

I've known of two incidents where boats got in big trouble with a
preventer rigged. One ended up gybing anyway, turning about 120
degrees and getting stuffed when the main went aback; the other
narrowly missed getting run down by a large tow as the skipper tried
to direct the crew how to unrig the preventer quickly so he could
turn. Both cases were of course caused by inattention, not the
preventer. But the preventer doesn't do anything a good helmsman can't
do.

The times I've sailed other people's boats with preventers rigged, it
always seemed more in the way than helpful.

DSK