Outhaul tension - how much?

[Richandhelen]

Okay, what is the "proper" amount of tension to put on my outhaul? I've always assumed that the foot of the sail has to remain reasonably parallel to the boom when I'm sailing in moderate winds. But this week I had the block at the mast foot explode its shackle. I tension with an electric winch. P.s. Lewmar was kind enough to send me a new block.



I know that marking the clew position on the boom is common. But how do you place the marks?

 

[Calif. Ted]

Usually the boom is marked at the "E" measurement which is the foot length of the sail, maximum extension would be there. Normally you adjust tension of halyard against outhaul tension to adjust draft to suit wind conditions. You want it full out for flat sail in high winds looser for more draft in lighter airs.

 

[Richandhelen]

Usually the boom is marked at the "E" measurement which is the foot length of the sail, maximum extension would be there. Normally you adjust tension of halyard against outhaul tension to adjust draft to suit wind conditions. You want it full out for flat sail in high winds looser for more draft in lighter airs.

So in light air would you expect to see curvature at the foot of the sail? A sail shape like the foot of the jib?

 

[Calif. Ted]

Yes, even in higher winds there is some camber in the main, main and jib are usually trimmed to "match" somewhat. Looking for a picture to illustrate I'm using one of some friends in a race, they are close hauled and slightly overpowered but everything is about as tight as it'll go. Their sail is not loose footed and still has some camber even constrained by the foot. A loose foot is going to exhibit more curvature at the foot where it is not constrained by the boom.

 

[Davidasailor26]

You definitely want less tension than you've been using. For example, the tuning guide for our loose footed roller furling main recommends that the foot of the sail should curve to about 8" away from the boom in winds up to 8 kts. They recommend reducing that to 4" by 12 kts, and reducing to flat as needed with increasing wind to depower the sail. In very light winds you may want to keep the sail flatter to keep the flow attached and tell tales flying, but that shouldn't be an issue above 5 kts of wind or so.

 

[Richandhelen]

You definitely want less tension than you've been using. For example, the tuning guide for our loose footed roller furling main recommends that the foot of the sail should curve to about 8" away from the boom in winds up to 8 kts. They recommend reducing that to 4" by 12 kts, and reducing to flat as needed with increasing wind to depower the sail. In very light winds you may want to keep the sail flatter to keep the flow attached and tell tales flying, but that shouldn't be an issue above 5 kts of wind or so.

OMG have I been over-tensioning my main!

 

[Joe]

You can also think of the outhaul as the flaps on your wing or a gearshift in your hot rod. More draft depth equals more power. A flatter sail will allow higher speed...

I adjust my outhaul with an eye on the speedo.

 

[uncledom]

Talk to your sail maker. The foot of the main should always be in line with the boom unless you are running. The sail maker built the curve in the sail, any additional belly only adds drag. So the outhaul tension matches the wind pressure for the most part.

 

[Richandhelen]

Talk to your sail maker. The foot of the main should always be in line with the boom unless you are running. The sail maker built the curve in the sail, any additional belly only adds drag. So the outhaul tension matches the wind pressure for the most part.

Does this not conflict with davidasailor26 (above) advice? I am re-confused. Is the difference that I have in- mast furling and thus a loose- footed main?

 

[Jackdaw]

So in light air would you expect to see curvature at the foot of the sail? A sail shape like the foot of the jib?

Yes, like this. Our main in 7 knots. Always look at the draft stripes to get a feel of depth and max draft location. The trick is to get good flow across a powerful shape. Outhaul and backstay tension control the shape.

 

[Scott T-Bird]

Richandhelen, keep an eye on the forum "Sail Trim with Don Guillette". If sail trim interests you, you'll enjoy participating.

 

[Richandhelen]

Yes, like this. Our main in 7 knots. Always look at the draft stripes to get a feel of depth and max draft location. The trick is to get good flow across a powerful shape. Outhaul and backstay tension control the shape.

I have a B & R rig with no backstay. My real question is whether the main, on an in-mast (loose-footed) furler should sometimes be "off" the centerline of the boom or should in almost all wind conditions, remain "taught" (e.g. in-line) with the centerline of the boom? This is unclear to me. And the responses seem to differ. Rich

 

[Jackdaw]

I have a B & R rig with no backstay. My real question is whether the main, on an in-mast (loose-footed) furler should sometimes be "off" the centerline of the boom or should in almost all wind conditions, remain "taught" (e.g. in-line) with the centerline of the boom? This is unclear to me. And the responses seem to differ. Rich

One of the big shortcomings of the B&R rig is its lack of backstay to help shape the mid section of the mainsail. Nevertheless, in light to moderate breeze you want a powerful, full shape in the sail wherever you can. Easing the outhaul will add this to the bottom half of the sail. That means the foot of the mainsail will be off the boom and take an airfoil shape.

 

[Gunni]

So to get you started toward sorting this out:

• Yes, the foot of the sail should almost always be off the the centerline of the boom. Maybe 30 kts of wind would have you reefed down and that foot flat 'n tight.
• Quit using your electric winch to adjust your outhaul. Luff up a bit, give it a tug, cleat it off, and you are done.

 

[Joe]

Talk to your sail maker. The foot of the main should always be in line with the boom unless you are running. The sail maker built the curve in the sail, any additional belly only adds drag. So the outhaul tension matches the wind pressure for the most part.

Never heard that before....

 

[Joe]

Does this not conflict with davidasailor26 (above) advice? I am re-confused. Is the difference that I have in- mast furling and thus a loose- footed main?

That's because it's not correct advice. Get a hold of any sail trim guide (you could start with Don's) to understand what good sail shape is and how to achieve it....

 

[uncledom]

Well my sail makers advice keeps me moving faster than my competition which is every one sailing in the same direction. When close hauled that foot is almost always in the center of the boom. It is a furling main with a loose foot. It is never to be more than 4 inches off the boom unless your running and using it like mom's bed sheet. The sail maker built the camber or draft into the sail, any additional belly causes the sail to create more drag than lift until you get separation of laminar flow which I'm sure you don't have enough tell tales to see this happen. Sail twist is independent of outhaul tension and is controlled via the boom vang and or topping lift depending on your boat configuration. My 2006 Hunter 41 AC did not come with a proper boom vang. It came with a Seldon kicker without the internal piston so the boom will not rise without a topping lift or wind pressure. For around $100 you can buy the piston and install it quite simply. Apparently the vang assembly was meant to be used as a stop to ensure the boom didn't hit the arch traveller. This is a good upgrade for all Hunters of this era. I would suggest you buy Don's sail trim guide and also experiment on your own. If you don't learn something on every sail, IMHO, your not doing it right. I will keep setting my sails as I have described and you can tell me if my stern light is working.

 

[Richandhelen]

Well my sail makers advice keeps me moving faster than my competition which is every one sailing in the same direction. When close hauled that foot is almost always in the center of the boom. It is a furling main with a loose foot. It is never to be more than 4 inches off the boom unless your running and using it like mom's bed sheet. The sail maker built the camber or draft into the sail, any additional belly causes the sail to create more drag than lift until you get separation of laminar flow which I'm sure you don't have enough tell tales to see this happen. Sail twist is independent of outhaul tension and is controlled via the boom vang and or topping lift depending on your boat configuration. My 2006 Hunter 41 AC did not come with a proper boom vang. It came with a Seldon kicker without the internal piston so the boom will not rise without a topping lift or wind pressure. For around $100 you can buy the piston and install it quite simply. Apparently the vang assembly was meant to be used as a stop to ensure the boom didn't hit the arch traveller. This is a good upgrade for all Hunters of this era. I would suggest you buy Don's sail trim guide and also experiment on your own. If you don't learn something on every sail, IMHO, your not doing it right. I will keep setting my sails as I have described and you can tell me if my stern light is working.

Okay, now I'm forced to REALLY bare my soul for all the (sailing) world to see. I'm supposed to actively use my TOPPING LIFT!? I thought that was there to prevent the boom from falling through the Bimini if the rigid vang failed and to provide an annoying "clanging" noise on all other points of sail. I really need that guide I thought I didn't need!

 

[Jackdaw]

Well my sail makers advice keeps me moving faster than my competition which is every one sailing in the same direction. When close hauled that foot is almost always in the center of the boom. It is a furling main with a loose foot. It is never to be more than 4 inches off the boom unless your running and using it like mom's bed sheet. The sail maker built the camber or draft into the sail, any additional belly causes the sail to create more drag than lift until you get separation of laminar flow which I'm sure you don't have enough tell tales to see this happen.

Sorry, but your comment about the foots relation to the boom is not good advice. Proper shape based on wind speed should be created down the entire length of the sail. In lighter condition this will result in a deeper sail, and the foot will be well off the boom. That means easing the outhaul, no matter the point of sail.

How far? You have to experiment. Watch your speed, and look up your sail at the angle of my picture. Have leech and body telltails.

On my two boats I'm lucky; we have polar charts from the designer that says how fast we should be based on wind speed. Without that sail depth when the breeze is light we can't hit our numbers.

 

[Richandhelen]

Sorry, but your comment about the foots relation to the boom is not good advice. Proper shape based on wind speed should be created down the entire length of the sail. In lighter condition this will result in a deeper sail, and the foot will be well off the boom. That means easing the outhaul, no matter the point of sail.

How far? You have to experiment. Watch your speed, and look up your sail at the angle of my picture. Have leech and body telltails.

On both our boats we're lucky; we have polar charts from the designer that says how fast we should be based on wind speed. Without that sail depth when the breeze is light we can't hit our numbers.

I just went on to Amazon and ordered a sail trim guide. I am truly humbled by my lack of knowledge. I have (apparently) often been using too much outhaul, setting my jib using the telltales, letting the main out just until it luffs and then pulling it in a bit until it stops. I STILL have no idea how or when to use my topping lift OR my rigid vang:confused