Trim for gaffers

[waters'l]

I have been lurking for quite a while and have hoped to find a thread devoted to gaff sail trim. I haven't found one so I thought I would start this. I have a DeVries Lentsch sloop with a proportionaly large main and a 50 degree gaff. I have found that peak trim is super crucial. Upwind, keeping the peak high helps reduce sag to the point where I only use the vang to keep the gaff off the shrouds when running. Only recently have I found the benifit of lowering the peak off the wind. I was in 10 kts and flat seas trying to catch similar sized modern race tub, (they really hate getting passed by an old boat) I wasn't making any progress when I lowered the peak 2 or 3 degrees. The mains'l bellied out some and I could feel the old girl take the bit and go. It made the diference between looking pretty and ruffling some racers feathers. What tricks have you found with your gaffer? Im still a bit mistified with boom position for beating and I'm sure there are lots of other things I don't eaven know I should be thinking about. Gotta love the versital, adjustable gaff rig.

[John B]

nice to see a lurker coming out.:)
50 degrees off vertical ?

Its a standard tuning circle. You start with the headsail and work back. Windward work is all based around jib luff tension.Then sheet angle , then staysail, then main.
People make the assumption that a gaff boat performs as it does because of the obvious difference and that is the 4 sided main. Thats a red herring. If your jibs aren't right , the most perfect main set in the world won't do squat.
As to main trim and shape, It goes 2 ways depending on how the gaff is set up. If its set up to bend . Like the wiannos( Thanks Ian) where they don't reef and have to carry full sail through, then the gaff works the same as a modern fractional where bend flattens sail.Ie they sweat on peak to flatten and depower.
If the gaff isn't designed to bend a great deal, then you can get the opposite where peak tension pulls more draught into the sail ( tightening the peak or slackening the throat acheives much the same )
Thats how ours works generally.

[Ian McColgin]

I think Getting Salty meant that the gaff peaks up to about 50 degrees, which is fairly average. A schooner's foresail often has a gaff that's a bit closer to horizontal and boats like Marmalade (25' catboat) have very high peaks with long long gaffs.

But the notion of keeping her a hair off the wind, at 50 degrees and tacking through 100 degrees, rather than the modern sloop's 45-90 or even tighter, is good as well.

Good observation about easing the peak a nudge off the wind. All the Wianno fleet does that but I've noticed that gaff rigged boats that are not raced don't bother. Pity. It's well go get the best of a boat.

My first theory of luff and peak tension is tighten the luff till wrinkles parallel to the luff won't come out when the sail is full. Then ease the luff till they do. Tighten the peak till the radiating creases appear and then ease till they go. This works as a first approxomation on the wind.

Many boats are dictated by jib trim but not all. Experiment with getting close to the wind with the jib loose and then see what happens as you trim the jib. Compare that to best main trim following best jib trim. By the way, if you don't have flys on your jib's luff, despair not. Sit to leeward and stare at the jib's luff till you can see that first going soft before luffing. That's where you want to be.

G'luck

[George.]

Easing the peak helps, not only when running. It improves reaching and even close reaching in light airs. And when running in light airs in a seaway, it does wonders to keep the boom from snatching or accidentally gybing.

Another tip: gaffers tend to have thick masts with lacing or hoops. That means that the first few inches of the luff will be in turbulence when close-hauled, no matter what you do. They will flutter a bit. This can drive you to oversheet the main in an attempt to improve set, which might make it look better, but actually makes things worse. Stitch some telltales or a nice flag into the leech of the main, one-third and two-thirds of the way up, and trim by those.

And finally: when stopping briefly for lunch or a swim, you don't necessarely have to drop the main on a gaffer. Ease the peak, maybe haul up the boom a bit with the topping lift, and watch her sit placidly at anchor, even in a breeze, with her sail fluttering gently like in a seventeenth-century Dutch painting... :)

[outofthenorm]

As I understand things, supported by 25 years with my gaffer, a critical factor for gaff sail performance, especially upwind, is the relative angle off-center of the gaff and boom. In many setups, when the sheets are eased, the gaff falls off more than the boom and when they are trimmed, the boom comes in tighter than the gaff. The big twist that this induces is a killer for laminar flow. When you try and bring the gaff in by hardening the sheets, the leach gets hooked and you might as well be hove to.

The best remedy is to fit a powerful vang arranged to pull the boom DOWN. The magic is that when you haul the boom DOWN it pulls the the gaff IN. Thus you're using the sheets to control the boom angle and the vang to control the gaff angle. You don't have to oversheet any more. My vang is a big 4-part self-cleating tackle that is attached to a strop mid-boom and hooks into a strong point on the deck, right at the rail. It gives me fine control over the amount of twist in all wind stengths. If your spars are light, you have to take care with how much it flattens the middle of the sail. Too much and the leach will deform. You also have to make it strong - there are BIG loads when it's blowing.

When I first started sailing gaff rig, I sewed thread telltales all over the sail (about 40 of em) so I could see what was going on when I pulled on all the strings. It was a real education. Now I set the sail exactly as Ian does and trim by the flag that streams from the top of the leach. If it's flowing, the sail is working. With so many possible adjustments, it takes a while to sort out. - Norm

- Norm

[Mr.O]

checking my login

[dsfixit]

I have ben looking for info on gaff sails on triming and so on and the info
that was giving helps . im new to sailing and like the look of the sails
with some luck im looking at a ketch with gaff sails im hoping it wall be
my new boat . if thing work out knock on wood!!

[Wild Wassa]

"It made the diference between looking pretty and ruffling some racers feathers."

I know what you mean Skipper, some sailors get up to a heady 13 knots and they think that they are going fast.

Come and have a ride with me, have you ever been in a Gwen 12 ... as in only twelve foot of little boat? How close to twenty one knots were you really going? ... we all have GPS units.

If you would prefer a real racing skiff to compare speed ... let me know.

Warren.