Thread: GIS - running downhaul aft, need suggestions

Originally Posted by woodeneye

Two weekends ago we had 29 knots and it started pouring rain to boot. Racing was abandoned, so I left the Goat on the shore and took out the club's really old Laser with its radial rig, and with another full rig Laser, we had an impromptu two laps "race" around the set triangular course while everyone else was getting into the fridge stocks in the clubhouse.

Sorry to steer this further off topic, but I can't help wondering: Was the Radial rig as fast to windward as the Full rig in the breeze? -- Grant

I've decided to try a simple downhaul rig with a camcleat attached directly to the lower block, and to run the extra line back to the where I can reach it - along the dagger board, and over the middle seat, probably attached in some way to my main sheet lower block bridle so that it won't slip forwards out of reach. The idea is that if I set the camcleat angle just so, then I can release it, and re-cleat it from a distance. I'll let y'all know how this works out.

I'll contribute to the jibing stories. (Lost a laser race jibe flipping in high wind, that was a off). Sailing the goat on tsunami day here in San Diego, there was a strong tidal surge into and out of the harbor I was sailing at. It seemed to switch direction every ten minutes or so and was moving a lot of water. After a turn in the ocean, I was sailing back in through the harbor mouth jetties. The water was boiling with turbulence of the flow going out of the harbor at that time. I know I'm doing about five knots, as I was doing so before reaching the harbor on the same point of sail, but I'm barely making headway in the reversed surge. Slowly getting inside the turning basin, I needed to jibe, but I forgot - there is a lot of force on the sail - firm tailwind, no forward ground speed. That boom came across like a rocket!

Two guys are up on shore watching the tidal surge, and one yells, "You're lucky". So I'm thinking that could be interpreted in several ways.
(1) You're lucky to be sailing in such fun and unique conditions.
(2) You're lucky to be alive sailing in such unique and possibly dangerous conditions.
(3) You're lucky that you still have your head attached after that jibe.

I chose to respond as if he meant (1), but have a strong feeling that he meant (2) or (3). )

Originally Posted by Old Yeller

Sorry to steer this further off topic, but I can't help wondering: Was the Radial rig as fast to windward as the Full rig in the breeze? -- Grant

In that strong a wind and with our weights, the Radial was the better and faster rig.

A bit off topic: The Radial sail is now into its 6th revision. There have been changes to the cut of the sail, the orientation of the cloth and there is now some broad seaming. The changes have made the sail more adaptable to different conditions, more powerful in light medium and can be depowered more in a breeze. It's no accident that the light weight cloth is very stretchy. As far as I know, the full rig sail is still cut flat and the luff curve alone provides the shape.

Originally Posted by warm beer

Two guys are up on shore watching the tidal surge, and one yells, "You're lucky". So I'm thinking that could be interpreted in several ways.
(1) You're lucky to be sailing in such fun and unique conditions.
(2) You're lucky to be alive sailing in such unique and possibly dangerous conditions.
(3) You're lucky that you still have your head attached after that jibe.

I chose to respond as if he meant (1), but have a strong feeling that he meant (2) or (3). )

You chose the best answer - it makes your every move appear intended and graceful!

MIK

HI Bruce,

I heard that when they increased the cloth weight for the full rig a few years ago that they might have introduced some broadseaming.

The old sail used to sit pretty flat on the ground - so that indicates none or very little. I've never seen the "new" (must be a decade old now) heavier sail on a loft floor to know.

MIK

OK, the simple downhaul rig with a lower block mounted cleat worked great. I could release and re-engage it without going forward.

Gusting to 15 knots I noticed that the leech above my upper batten was flapping a good bit while close hauled, trying to chase down an Erickson. There is no leech line to snug this up. Is this a fact of life as the gaff twists in a prolonged gust?

Does anyone have a perfect distance from the luff to attach the gaff block? This appears to be an important constant when tuning the sail, (which I am still working on).

Originally Posted by Boatmik

HI Bruce,

I heard that when they increased the cloth weight for the full rig a few years ago that they might have introduced some broadseaming.

The old sail used to sit pretty flat on the ground - so that indicates none or very little. I've never seen the "new" (must be a decade old now) heavier sail on a loft floor to know.

MIK

I do know that it was some time in the late '80s that Laser switched from 3.2oz to 3.8oz dacron cloth. It hasn't seemed to make much difference, as the cloth is impregnated with with something that makes it feel softer. I could be wrong, but I believe it is only the Radial sail that has some broadseaming now. The iSails and Intensity "training" sails (illegal for racing) use similar weight dacron cloths, but they are untreated, so seem heavier. They have that crinkly characteristic and are harder to change shape with the controls, ie. they don't stretch as much as the legal sails.

It's a funny thing, but if you look at old Laser pics from the 70/80's the sails had a much better shape than they do today. They were Elvstrom sails back then. (Hans Foch designed the Laser sail for Bruce Kirby, and he worked for Elvstrom sails) Something has definitely happened since Norths and Hyde have become the sole suppliers, even though the literature is adamant that the same templates are used today. Anyway, there is a bit of unrest amongst some Laser sailors that the current sails go to rubbish so quickly. At a recent Worlds, it was Norths who supplied the sails, and they got an absolute bagging as the shape disappeared after just 3 races. Apparently the depth just went too far back, and no amount of Cunningham could fix it. Fortunately, everybody was in the same boat (haha, that's the advantage of one design), so it didn't affect the result.

Another reason might be the extra power available from the controls nowadays. For instance, the Cunningham has gone from 2:1 to 8:1, and the Vang from 4:1 to 15:1. It's possible that all this power is what is ruining the sails shape so quickly.

Maybe it's all to do with the sailcloth quality nowadays? Just as well then that Laser sails have come down in price from over AU$1000 to AU$583, so I won't be complaining too much!

Draft will tend to move to where the most tension is. So if you have a really powerful vang the draft will tend to move back.

And if there is permanent stretch ... it won't move back even when you let the vang off.

Sail cloth is a bit heavier, but the loads have gone up a lot.

Maybe they should have stuck with the lower vang loads.

Broadseaming of course gives the sail a lot less choice about where the draft can go.

MIK

Cool! while we're on the subject of sail cut and shape - Mik and Wood, what do you think about vertically cut Goat Island Skiff sails, versus cross cut, or the modified cross cut sail on Gruff? The sail I picked up here in the U.S. is vertically cut, but it appears that the sails made in the land of the summer Christmas are predominantly cross cut.

From my limited research, I've read that cross cut sails have the advantage of improved shape, while vertically cut sails are favored for longevity as the leech is composed of one uninterrupted panel. The vertical cut camp says that the shape can be matched through broadseaming, but how does this all relate to the balanced lug rig like the Goat has, with flexible boom and yard?

Possibly there is a benefit in the vertical cut from stability in the shape and the panels are narrower and there will be less stretch.
I don't know enough about sailmaking to know the answer. For all I know, it may just be looks.

I'm sure member, Andrew Denman, won't mid me posting a pic here from his website (About Denman Marine wooden boat builders) The same sailmaker (Storm Bay Sails) made my sail, which is cross cut, but using the same cloth.

Attachment 167902

Originally Posted by warm beer

Cool! while we're on the subject of sail cut and shape - Mik and Wood, what do you think about vertically cut Goat Island Skiff sails, versus cross cut, or the modified cross cut sail on Gruff? The sail I picked up here in the U.S. is vertically cut, but it appears that the sails made in the land of the summer Christmas are predominantly cross cut.

From my limited research, I've read that cross cut sails have the advantage of improved shape, while vertically cut sails are favored for longevity as the leech is composed of one uninterrupted panel. The vertical cut camp says that the shape can be matched through broadseaming, but how does this all relate to the balanced lug rig like the Goat has, with flexible boom and yard?

With very big sails there is some advantage for longevity. But i have never really noticed much difference between crosscut and vertical cut in the size of boats we can afford. The dinghyracing guys flip backwards and forwards between crosscut and other cuts where the fabric is aligned more closely with the sail loads - so that indicates there is not a great advantage in performance one way or another. With yacht sails the directional cuts have become quite dominant - indicating that in bigger sizes there is a significant advantage ... probably. Though I do know a couple of sailmakers that say a nice crosscut sail in these sizes has advantages too.

There are two main factors in sail life.

1/ Modern cloths have resin fillers that tend to be damaged by sails being folded and crease or flapping around. The softer a cloth is to touch, the less resin and heat has been used to fill the weave of the cloth. This filling reduces the amount of bias stretch so the sail is more stable in different windspeeds - the draft doesn't move around as much in each gust.

I specify a medium or softer finish cloth - most dinghy sails don't scrunched down when reefed or sat on when rowing or the many varied mistreatments of our sorts of boats. So the softer cloth is a better choice.

2/ Flapping - particularly when the boat is sitting on a beach. But the good thing about our traditional sails is they don't flap around anything like a modern dinghy sail. I think is is about having "roach" on the modern sail that makes them flap so much. The lugs and sprits just seem to sit there happily.

I think the direction if the cut is so much less important than these two.

Best wishes
MIK

Thanks Mik and Wood. Maybe there is no significant difference between vertical and cross-cut sails. I'll keep working on tuning mine. I'm going to try both battens out next with a tighter outhaul. I did notice the other day that pointing in gusts over 15 knots with the full sail, the roach flapped quite a bit. I had her sheeted out slightly, but I had complete control and plenty of power. It's been awhile since my laser and FJ racing days, but I think I would have had much less control in the same wind and a lot more weather helm.

It would be really nice if I could figure out a way to control the amount of flex in the boom on the fly. From my continued research on sail shape in different wind strengths, with the flexible boom, it would be nice to be able to keep it as straight as possible in light wind conditions for increased camber, and more flexible as the wind strength increases for a flatter sail. Maybe it's just a matter of doing what other folks are doing - making a stiffer boom for their Goat.

Originally Posted by warm beer

Thanks Mik and Wood. Maybe there is no significant difference between vertical and cross-cut sails. I'll keep working on tuning mine. I'm going to try both battens out next with a tighter outhaul. I did notice the other day that pointing in gusts over 15 knots with the full sail, the roach flapped quite a bit. I had her sheeted out slightly, but I had complete control and plenty of power. It's been awhile since my laser and FJ racing days, but I think I would have had much less control in the same wind and a lot more weather helm.

It would be really nice if I could figure out a way to control the amount of flex in the boom on the fly. From my continued research on sail shape in different wind strengths, with the flexible boom, it would be nice to be able to keep it as straight as possible in light wind conditions for increased camber, and more flexible as the wind strength increases for a flatter sail. Maybe it's just a matter of doing what other folks are doing - making a stiffer boom for their Goat.

A stiff boom combined with a loose foot gives better control over sail shape, as you control the power down low with the outhaul very easily and quickly. In a strong breeze like 15 knots, pulling the outhaul tighter not only flattens the sail to depower it, but also opens the leach which is what you want to reduce weather helm as the wind gets up. With a sail lashed to the boom, you have less control over the leach, so the way you might do that if you have a fully battened sail is to reduce the batten tension (takes out the curve).

If the leach flaps, that is really bad. The battens will probably help a lot though. Also, pull on the downhaul more, or add a kicker. If your sail has a leach cord, tighten that up a bit. Not too much as you only want to control that flapping.

I haven't got the time right now, but if you like I can post a diagram tonight which shows how the leach opens when the outhaul is tensioned. You may already know how it works, so let me know.

Hey Wood, (american for Hi)
I would love to see that diagram. I think it's pretty interesting stuff.

My sail does not have a leech line.

I'm guessing that a tighter outhaul would not only create tension from tack to clew, but also from throat to clew which would tilt the gaff, raise the peak and thus tighten the leech?