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Old 03-19-2010
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Forestay tension = pointing

How does forestay tension effect pointing?

On my Merit 25 (15/16th fractional) I have uppers, lowers, and swept back lowers which are usually used as ckeck stays to limit mast bend. On the forestay I have a tuff luff and the backstay terminates in a 24:1 cascade purchase. The sails are in pretty good condition. The main is full battened tri radial pentex cut pretty flat (thinking of adding softer battens) and the headsail is a 155 Technora laminate (Fusion M) from Quantum which is brand new. Been used in 2 races. The problem Iím having is that the boat is tacking through 100-110*. This is not good considering I do a lot of W/L racing. The bottom wasnít in great shape which Iíve stripped down to gelcoat and re-do before launch. Iíve also noticed that after making templates for the keel, the center of the keel is a little Ďfatí and the leading edge is a little ďskinnyĒ, which Iím fixing. Essentially, Iím moving the draft forward in the foil.

I understand that adding tension in the forestay will remove the curve and flatten the sail, depowering it. How exactly does this effect the ability of the boat to point to windward? How can I take a methodical approach to finding the optimal headstay sag? The reason Iím really worried about this is b/c before I changed the backstay set up and got new sails, the boat pointed great with baggy sails. I also have added a significant amount of rake to the mast as well (which is what Meritís like Iím told).

Iím just a little dissapointed in spending litterally thousands to go faster and higher, and now have gone backwards.
-I think that covers it.
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Quote:
Originally Posted by zz4gta View Post
How does forestay tension effect pointing?

On my Merit 25 (15/16th fractional) I have uppers, lowers, and swept back lowers which are usually used as ckeck stays to limit mast bend. On the forestay I have a tuff luff and the backstay terminates in a 24:1 cascade purchase. The sails are in pretty good condition. The main is full battened tri radial pentex cut pretty flat (thinking of adding softer battens) and the headsail is a 155 Technora laminate (Fusion M) from Quantum which is brand new. Been used in 2 races. The problem I’m having is that the boat is tacking through 100-110*. This is not good considering I do a lot of W/L racing. The bottom wasn’t in great shape which I’ve stripped down to gelcoat and re-do before launch. I’ve also noticed that after making templates for the keel, the center of the keel is a little ‘fat’ and the leading edge is a little “skinny”, which I’m fixing. Essentially, I’m moving the draft forward in the foil.

I understand that adding tension in the forestay will remove the curve and flatten the sail, depowering it. How exactly does this effect the ability of the boat to point to windward? How can I take a methodical approach to finding the optimal headstay sag? The reason I’m really worried about this is b/c before I changed the backstay set up and got new sails, the boat pointed great with baggy sails. I also have added a significant amount of rake to the mast as well (which is what Merit’s like I’m told).

I’m just a little dissapointed in spending litterally thousands to go faster and higher, and now have gone backwards.
-I think that covers it.
My first guess is that you're flattening your sails too much. There is a common misconception that you have to have your headstay bar-tight to make the boat point. You need an appropriate amount of draft in your sails, relative to the windspeed and the size of waves and boat wakes, to generate enough power so that the boat can accelerate up to it's maximum potential speed. Speed begets pointing. As your boatspeed increases, the ability of the boat to point also increases. Your sails should only be flat after the boat is at it's best speed. Whenever your boatspeed decreases, you need more draft in your sails to make it accelerate back up to speed. If the sails are too flat, the boat will be slow in accelerating to it's maximum speed.

I have been crewing for a number of racers on the Chesapeake, and have been surprised to see many of them raise their sails before the start of a race, and then they never again touch any of the sail shaping devices that they have available to them, regardless of the direction they're sailing relative to the wind, and even though the conditions in which they're sailing have changed. IMHO, one of the most useful sail controls you have is the adjustable backstay, because it enables you to instantly change the shape of both sails from flat to full, and any shape in between.

My present boat is not a racer, but my previous boat had an adjustable backstay, and, whenever I headed off the wind, I eased the backstay adjuster. When the wind gusted hard, I increased the tension. In a lull, I eased the backstay. When I tacked, I left it full through the tack, and then gradually increased backstay tension as the boat accelerated up to speed. The person who is adjusting the backstay should watch the helmsman's hand on the tiller during the tack. As the helmsman gradually steers the boat up to windward, crew should gradually increase tension on the backstay in coordination with the helmsman. The same applies to the jib trimmer. Watch the helmsman's hand on the tiller, and, as the helmsman gradually steers the boat up to closehauled in small increments, the jib trimmer should gradually trim the jibsheet in coordination with him, until the jib is trimmed for the new closehauled course.

In a sailboat race, the conditions of wind and waves change constantly as you proceed around the race course. With every change, you need to use all the sail shaping devices available to you so that the boat's speed and pointing ability are optimized for the highest possible percentage of the time, all the way around the course.

Last edited by Sailormon6; 03-19-2010 at 10:50 AM.
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What true wind speed are you talking about and how have you been managing your sheet leads to shape the sail?
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Wind speed was light, over 3 days it fluxed from 4k up to 13k. Did 9 races total. With more breeze it seemed to point a little better, but still not w/ the fleet. Jib leads were set far forward so the tells broke evenly up the luff.

For some reason I thought I was using too little backstay, resulting in a sloppy forestay and hurting my pointing. W/ the adj. backstay setup I have now, I can completely blow the backstay resulting in litterally 0 tension. Not bad for down wind, but I think my "internal gauge" is set up too soft and I need to crank more on going upwind. In light air I usually tighten the backstay just enough to take out any flopping around on the headstay.

Solomon, thank you for your response, but I don't believe this to be a problem of trying to point before top speed. That would mean we just took a long time to get up to speed (switch gears) and then would have been able to point. Even w/ the boat at and above hull speed, the boat still did not point.
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Your halyard tension may also be an issue.. we found with Pentex jibs you needn't over tension your halyard. It pulls the draft forward leaving you with a wider angle of attack, forcing you lower to get the telltales flying.

Try easing the halyard and see if your pointing ability improves.
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In light air the halyard was loose enough to just barely see scallops in the luff.
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Quote:
Originally Posted by zz4gta View Post
Wind speed was light, over 3 days it fluxed from 4k up to 13k. Did 9 races total. With more breeze it seemed to point a little better, but still not w/ the fleet. Jib leads were set far forward so the tells broke evenly up the luff.

For some reason I thought I was using too little backstay, resulting in a sloppy forestay and hurting my pointing. W/ the adj. backstay setup I have now, I can completely blow the backstay resulting in litterally 0 tension. Not bad for down wind, but I think my "internal gauge" is set up too soft and I need to crank more on going upwind. In light air I usually tighten the backstay just enough to take out any flopping around on the headstay.

Solomon, thank you for your response, but I don't believe this to be a problem of trying to point before top speed. That would mean we just took a long time to get up to speed (switch gears) and then would have been able to point. Even w/ the boat at and above hull speed, the boat still did not point.
Assuming that your keel is fair, your bottom is clean and your sails are of competitive quality, the most likely remaining explanation for your inability to point with other comparable boats, or boats in your class, is that they're trimming their sails better than you. That was the meaning of my last post. Some of your comments confirm that.

You said, " Wind speed was light, over 3 days it fluxed from 4k up to 13k. Did 9 races total. With more breeze it seemed to point a little better, but still not w/ the fleet." That says you weren't sailing well in light air, and that's probably because you weren't trimmed correctly for light air. .
Read any treatise on sail trim, and it'll tell you to unstrap your sails in light air.

You said, "For some reason I thought I was using too little backstay, resulting in a sloppy forestay and hurting my pointing." Your thinking in that regard is mistaken. In light air, even when sailing to windward, the backstay adjuster should be eased more than you imply, and the jib halliard should also be eased until the jib luff is nearly scalloped. ( I occasionally crew for a friend who is a consistent winner in a very competitive fleet, and he won his class in Annapolis Race week in light air, and his jib luff was was not just relaxed, it was deeply scalloped. I probably would not have had such pronounced scallops, but it worked for him.)

In light air, you have so little air movement with which to drive the boat that you have to extract the maximum possible power from the little wind that is available. That means, as a general principle, that your sails must have the deepest, fullest shape. You achieve that by easing the backstay adjuster until the headstay has a slight catenary curve, and easing the jib halliard until the luff of the jib is at least on the edge of being scalloped. You also ease the mainsail halliard or the cunningham until the luff of the mainsail is completely relaxed. You also ease the mainsail outhaul until the foot of the mainsail is completely relaxed.

These adjustments aren't always the same in light air. When the wind is it's lightest, your sail shape controls should be their loosest. When the boatspeed exceeds about 2 1/2 kts, I start very gradually adding tension to the sail shape controls, because, as boatspeed increases, the wind can't remain attached to the surfaces of the sails if their draft is too deep.

Helmsmanship is also crucial in light air. When we're trying to get the boat to point high, our natural inclination is to steer it in that direction, just on the edge of luffing, but that's wrong. The expression that I have frequently heard is that you must "foot to point." In other words, pinching always results in the boat losing speed, and that reduces the boat's ability to point, especially in light air. If you want to sail as close to windward as possible, you have to bear off enough to maximize the boat's speed, and that will enable the boat to point higher. You only bear off slightly, until the speed is maximized, and then you can start steering closer to windward. If the boat's speed drops, then bear off again to regain your speed, and then steer close to windward again. You'll actually be sailing a slightly scalloped course to windward, but your average speed will be higher and your average heading will be closer to windward.

I also believe your pointing ability is being hurt in stronger winds by trimming your sails too tight. Your comments suggest an inclination to harden up all the sail shape controls in an effort to make the boat point, but boat speed and pointing ability go hand-in-hand. Even in 13 kt winds, you need your sail shape to generate as much power as the boat is capable of using efficiently. By flattening your sails too much for the available wind, the boat doesn't have enough power to achieve the speed necessary to point high.

Last edited by Sailormon6; 03-19-2010 at 02:04 PM.
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I believe Sailormon6 has very aptly summarized the situation. For a Merit 25, 13 knts is not a lot of wind. From your comments, I wonder too if you may be over trimming your Main, depriving yourself of drive and the benefit of the "slot effect", which really does matter on that class yacht.

N'any case, good luck...
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Old 03-22-2010
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I'm confused. I've read North's Trim book 4 times and like to think that sail trim is one of my strong points (in any breeze). My trimmer on board for those races has won his class in his boat twice, my tactician had won that event 9 times previously, and the bowman was also very experienced.

I finished fairing the keel and the barrier coat this past weekend. Maybe it was just a really crappy bottom. Or maybe my trim is really that far outta wack.
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Quote:
Originally Posted by zz4gta View Post
I'm confused. I've read North's Trim book 4 times and like to think that sail trim is one of my strong points (in any breeze). My trimmer on board for those races has won his class in his boat twice, my tactician had won that event 9 times previously, and the bowman was also very experienced.
I finished fairing the keel and the barrier coat this past weekend. Maybe it was just a really crappy bottom. Or maybe my trim is really that far outta wack.
Among sailors who have sailed for a lifetime, very few of them ever learn how to sail well in light air, and many of them have also read NorthĎs trim book. It's easy to sail in 12-20 kt winds, because there's such an abundance of wind that you can waste a little of it, and the boat will still sail fairly well. But, when you're trying to use 3-6 kts of wind to drive a boat weighing several thousand pounds, you canít afford to waste any of it. What that means is that you have to know every single technique that can be used to maximize the boatís speed and reduce drag, and you have to remember to use them all. If you waste only 5-10% of the power available to drive the boat in light air, the effect on the boatís performance will be dramatic. Sail trim is only one aspect of the light air puzzle. Tuning the rig, trimming the boat and light air helmsmanship are all important functions. Thatís why itís so difficult.

I have sailed with one or two brilliant young sailors who understand how to sail in light air, but they are rare. Regardless of your crewís racing success, if you arenít getting good results in light air, then sailing in light air probably isnĎt their strong suit. If it was, youíd probably be getting better results, and wouldnít be asking us for help. Itís possible that a foul bottom or other reason is responsible for your lack of success in light air, but I doubt it. About a year ago, I offered to sail with you on a light air day and try to help you, but never heard from you. The offer is still open.
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