Strange sail trim thing.

[Dave_S]

Sailing in around 10kn true and pretty steady direction, on a nice close reach, reasnobly calm sea state. The jib was working well (although it does get a lip on the leech) and I spent a bit of time getting the main just right so all the tell tails were all flying but it wasn't responding nicely.

The traveler was down a bit and the sheet off a bit to give some twist and all tell tails were flying, it was harder than usual to get everything flying but it looked good, felt crap.

I tried a bit more and less sheet with not much effect. Eventually tightened the sheet and completely stalled the top of the sail and the boat livened up so I ran the traver down, tighten the sheet, run the traveller etc.. to get the flow to re-attach, couldn't find a point where it was attached all over and it was slower.

It seemed as though it liked it stalled at the top. I assume it just allowed the rest of the sail to work more efficiently but surely there must have been a better set up and I just couldn't find it.

The halyard was tight but not super tight, the topping lift was loose and the outhaul was tight.

What else could I have tried ? Or is this sometimes just the case ?

[Suijin]

Standard procedure when trimming main is to get the bottom two telltales flying and the top one fluttering/stalling. If that's what you were seeing when the boat "livened" up, that's why. You were properly trimmed.

[Dave_S]

Originally Posted by Suijin

Standard procedure when trimming main is to get the bottom two telltales flying and the top one fluttering/stalling. If that's what you were seeing when the boat "livened" up, that's why. You were properly trimmed.

That's pretty much what I had when it was slow, I had the second from the top everywhere from streaming constantly to some flutter.

When the boat sailed it's best the top 2 tell tails were always behind the sail and the leeward on-sail tell tails down mostly but fluttering and the windward on-sail tell tails streaming horizontally.

[catsketcher]

It is good that you are still trying to trim better. I can't use many telltales on sails. I prefer to use a single leech telltale about one third down the leech for trim. Get it flowing and then trim on until it hides. I neglect all others.
When I raced Lasers you couldn't use telltales as the only way to get them to flow was on a close reach with vang off too much. When racing Tasars, which are more similar to multis, I often could reach over sailors who had lovely looking telltales when I was trimming on as hard as I could whilst still keeping my leech telltale happy. So forget the rest and sheet on till you lose the leechy. Simple and fast

[catsketcher]

What may be happening here is that your top two leechies are too high up. If you have a squarish top you may have to use a lower leech telltale. Eventually you will find one, maybe it is further down on your sail.

[PNWSalmon]

Also, you may want to ease your outhaul. In 10 knots true it shouldn’t be too tight. You can get more power out of the bottom 1/3rd of your sail with it a bit looser in those conditions.

[FabioC]

Does your main have a square head? What material is the sail?
In general, with a square head, try to use vang and cunningham (or even halyard tension) more and see what happens.
Most of the times, however, it is a matter of how the sail is [poorly] cut, which may make sometimes impossible to get the head to be properly trimmed at the same time as the lower half. Indeed, if that is the case, the tell tails can be misleading and make you, for example, trim the sail too flat for the conditions in an effort to have all the tell tails flying, and thus slower. The best you can do is to concentrate on the lower part, as you did, trim that optimally and then do what you can for the top. Generally speaking, that should be faster, albeit still not optimal. You can also take a bunch of pictures and have the twist in the sail modified in the off season...

[singlespeed]

I assume by the statement about "a lip on the jib" you mean the job's leach was cupped weather. If your jib is averaged sized, this "lip" is diverting air flow into the leading edge of the backside of the main, giving you misleading information. Take some of the tension off the jib's leach line. A slight a nothing flapping of the job's leach is preferable to a cupping leach.

Also, are you positive that they telltale are in the correct position. The sailmaker faces a myriad of decisions in placing the telltale. Mast shape and cross sectional size, rotating/non rotating, standing rigging windbag, etc. Put two rows of temporary telltales on your sails. At least four per row, one row a third of the way up, the other two thirds of the way up. Go sail and watch the numbers. Once you find the sail trim that gives you the best performance, note which telltale are consistently proving the correct feedback. That's where the telltale belong. The more you use you sails, the more often you need to check this. Sail draft moves back with age (not so much with aramid fibers), your telltale may be feeding you misleading information.

[Secondshift]

"Jib was working well" so... all tells in unison - good car placement.

"Jib lip on the leech" leech line over tight?

"Tightened sheet ... boat livened up. ...ran traveller down ... it was slower."

Maybe you were choking the slot. Sometimes in lighter air the proximity of main to jib can cause resistance to the flow. I try to make the spacing even and then work the traveller to adjust the proximity.

I tend to make small changes 1" - 2" and wait for them to settle in while watching SOG for effect. Intentionally going past best trim and then back to find the limits.

Best Regards

[ramblinrod]

What kind a f boat? How old are the sails?

[ramblinrod]

If your sails are old and baggy, no amount of trim will correct it.

Assuming the sails are excellent to very good condition, it sounds like you are depowering too much too soon.

You mentioned lowering the traveller with everything (luff tension, leech tension, outhaul, and mainsheet) tight.

Very little power trimmed flat like this, and usually reserved for high winds.

Instead of trimming flat from the get go, you may find it beneficial to start out loose, and as the boat speeds up (apparent wind speed increases) "change gears" just like you would in a car.

Start with everything more loose and the sails powered up. Traveller pulled up to windward, mainsheet out (lots of twist), luff tension (or Cunningham) loose, outhaul loose, vang loose.

As the boat speeds up, start adjusting (change gears) to flatten the sail, to suit the higher apparent wind speed.

Especially important after coming through a tack.

Trimmed flat, like it sounds you were, you are very close to the edge of stalling, and the boat will be very sensitive to coming up or falling off even a degree or two.