CP-23 Cutter

[Potcake boy]

Curtis

Flattening the sail is appropriate to higher wind speeds, but it isn't usually achieved with the sheet, but rather with tightening the luff and foot (in the case of my sail I only move the outhaul to achieve a deeper or flatter chord depth).  The main sheet tension controls the twist in the sail.  As you ease sheet tension the upper section of the sail falls off more than the lower section thereby producing more twist.  It can be visualized as having the upper half of the sail feathered to the wind as compared to the lower half which is still drawing.  Kind of like taking part of the sail out of play.  The traveler then allows proper trim angle of the boom to centerline without changing the sheet tension.  This is the quickest way to de-power your main and will often get you through the gusts without having to reef.  For boats without a traveler, the common practice is to ease the main sheet in gusts which both feathers and increases twist, problem is they can't do these independent of each other.  Just remember it by the old saying"sheet for shape and traveler for trim".

Ron

[newt]

You have almost convinced me Ron, to try a storm sail over my rolled jib. I just have one problem- What do I do with the jib sheets? They roll to about halfway up the forstay, and hang semi-lazily down to the deck. Seems to me any storm jib, except a arrow straight one, would get mixed up in the sheets. (Yes, you have to solve all my problems for me, since it is your solution! )

[curtisv]

Curtis

Flattening the sail is appropriate to higher wind speeds, but it isn't usually achieved with the sheet, but rather with tightening the luff and foot (in the case of my sail I only move the outhaul to achieve a deeper or flatter chord depth).  The main sheet tension controls the twist in the sail.  As you ease sheet tension the upper section of the sail falls off more than the lower section thereby producing more twist.  It can be visualized as having the upper half of the sail feathered to the wind as compared to the lower half which is still drawing.  Kind of like taking part of the sail out of play.  The traveler then allows proper trim angle of the boom to centerline without changing the sheet tension.  This is the quickest way to de-power your main and will often get you through the gusts without having to reef.  For boats without a traveler, the common practice is to ease the main sheet in gusts which both feathers and increases twist, problem is they can't do these independent of each other.  Just remember it by the old saying"sheet for shape and traveler for trim".

Ron

I should have said reduce twist when I said flatten sail.  The two sort of go together until you reach the point where you are overpowered and out of reef points and have to dump air out of the top of the sail, which I think is what you are getting at in suggesting that you ease the mainsheet when wind picks up (a real lot).

I understand the sheet for shape and traveller for trim but we don't have travellers on CP23 except for those that added them.

Anyway, as wind picks up the gradient of wind is reduced.  Twist is controlled by moving the sheeting point on the sailtrack and the mainsheet tension.  Another way of actually doing this on a tack is to bring the traveller over further for more twist and more over center or even to leaward slightly for less twist.  The traveller is faster to bring to windward before winching the mainsheet on a larger boat so it makes sense to move that first if you have a sense for where it will end up (which should be the same distance off center but on the other side).  Its the same thing.  Once you have the shape though, you are right that moving the traveller is the right way to adjust trim.

Without telltales on the main matching the shape of the headsail is the usual way to get the right twist.  The rule as far as I remember it is lots of twist in light air because the gradient of wind vs height is high.  Reduce twist as wind picks up.  Add twist if wind speed or direction is variable or if  waves are affecting trim.  When wind gets quite high, dump air out of the top of the sail by increasing twist.  This depowers the sail by dumping air, maybe not the best way to do it.  Its better to have the right reef in the mainsail and not dump air if you can do that without excess heel.  With a rather small second reef, and a fairly small headsail, I don't need to dump air until quite a bit over 25 knots.

Anyway, without a traveller none of this works quite right for the main.  What does work is easing the main and using a barber hauler in light air to get a lot of twist, but not a great solution either.

Did you say you have a traveller on your CP23?  I remember you mentioned loose footed main.  Do you have telltales on the main or do you try to keep the leach lines parallel looking forward? (I've heard it called keeping a clean slot between the sails).

Curtis

[Potcake boy]

Newt - as I mentioned, I have not owned one of these zip on storm jibs, and have puzzled over the same question.  I always tie a short bit of line around the jib immediately above the sheets when it is furled as a kind of safety so I think I could let the sheets zip into the sleeve, and just hang out the bottom.  That sounds like it should work OK.  If you tie the jib as described, you could then remove your sheets to use on the storm jib.  For all the years using hank on sails I always had a storm jib available, and used it enough to realize that a partially furled headsail is not an adequate substitute, and it's way too much of a pain to swap furled sails underway.  You always want sail reduction to be as easy as possible so your not reluctant to do it in good time.

Curtis - I have tell tales on the leech of my main and use them to judge good laminar flow over the main.  I always set the jib trim first and then set up the main trim accordingly.  Oh yeah, mine is a 19, and came with the same main sheeting as your boat.  I changed it to mid boom sheeting with a traveler for several reasons, but most importantly was the ability to control twist.  I don't think my mast is tall enough to be concerned with upper level gradients per se, however a good technique in dying wind that leaves a chop is to increase the twist to minimize pitching. As the boat pitches forward and apparent wind at the top of the mast changes, the top draws less thereby reducing the pitching effect.  It's really the same principle used when introducing twist in gusty conditions. I think you owe to yourself to try flattening (no twist) your main in lighter air - you can install tell tales on the leech to indicate if you are getting good flow all the way up.  Mine are located at the aft end of the 4 batten pockets.  But if your sail is an old Dacron it may not make much difference.  My boat is an '02' and the original sails were in pretty good shape, but were cut to deep for my taste and I really wanted a full batten loose foot so I had new sails made.  It actually makes this little boat go pretty good in light to moderate air - much better than I would have expected.

Ron

[curtisv]

Ron,

Teltails on the leach are certainly not much of an expense and it sounds like it would be worth it to find out how the air is flowing.  It would be interesting to see if matching the headsail shape turns out to be a reasonable method or if that does a lot better.

To be honest I check the telltales now and then to set the sail track position but don't bother staring at them the whole time I'm sailing to see if I'm still in trim.  I have noticed that I get a little more speed if I pay close attention to them rather than steering by feel.  Then again if I'm going to be on a very long tack (up to hours) I've lashed the tiller and not too worried if I lose half a knot.

Thanks for the advice,

Curtis

[Potcake boy]

Curtis

AARGH - I druther lash the winch whilst she holds me tiller.

Ron

[curtisv]

Ron,

Do us a favor.  In this case ***don't*** send photos.

Curtis