I was out today in my 1981 Hunter 27 in winds of 20-25 knots. I had only mainsail reefed at the first point. The boat stood up well and was stable, but developed very strong lee helm. There were times when I had the wheel hard to windward but could not tack. I expected that having only mainsail would produce weather helm, but just the opposite occured. Does anybody have an explanation?
Why lee helm?
- Thread starter Stephen OBrien
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Lee Helm
I think the Hunters are a mast head rig and in that case they won't tack or point without the Headsail flying. I have a Catalina 380 and she won't sail without the head sail up. Fractional rigs get there power from the mailsail, where Mast head rigs power from the headsail. I hope that helps a little. Regards Wayne
I think the Hunters are a mast head rig and in that case they won't tack or point without the Headsail flying. I have a Catalina 380 and she won't sail without the head sail up. Fractional rigs get there power from the mailsail, where Mast head rigs power from the headsail. I hope that helps a little. Regards Wayne
No headsail?
Are you saying you didn't have a headsail up? If not, the only thing I can think of to produce a foreward COE is that the mask is too far foreward. Sounds strange but if not, I would say it's impossible to have lee helm with just a main and the mask not be in front of the keel. Hey....maybe somebody moved your keel back
If you did have a headsail up, it was overpowering your main which with only one reef in the main would suggest the main wasn't trimmed right. If none of those, then maybe you have baricles on the lee side only
Are you saying you didn't have a headsail up? If not, the only thing I can think of to produce a foreward COE is that the mask is too far foreward. Sounds strange but if not, I would say it's impossible to have lee helm with just a main and the mask not be in front of the keel. Hey....maybe somebody moved your keel back
If you did have a headsail up, it was overpowering your main which with only one reef in the main would suggest the main wasn't trimmed right. If none of those, then maybe you have baricles on the lee side only Yep, no headsail
I agree that it doesn't make sense -- the mast is about where you would expect it to be. The only way I could tack is to fall off to pick up speed and then turn hard into the wind. Anyway, next time I will try a small amount of headsail, but I might need a second set of reef points to do that.
I agree that it doesn't make sense -- the mast is about where you would expect it to be. The only way I could tack is to fall off to pick up speed and then turn hard into the wind. Anyway, next time I will try a small amount of headsail, but I might need a second set of reef points to do that.
Ok....
More questions: 1 Did you have a strong cross current pushing to lee? 2 What was your wind angle? 3 speed? 4 heel? Maybe also your boom-vang was too tight and the outhaul too loose, causeing the bellie of the main to be too far forward. Not sure if that would do it but maybe.
More questions: 1 Did you have a strong cross current pushing to lee? 2 What was your wind angle? 3 speed? 4 heel? Maybe also your boom-vang was too tight and the outhaul too loose, causeing the bellie of the main to be too far forward. Not sure if that would do it but maybe.
Stephen - do you have tell-tales on your mainsail?
99% of the sailors and 'sailing authorities' descripitons of how a sail works is WRONG. Bernoulli doesnt apply, the designer's (concept) of center of effort doesnt apply, there is NO such thing as a *slot effect*, backwinding ISNT, .... your high school physics or science teacher had NO idea, etc. etc. etc. etc. All those 'principles' went into the trash can when aerodynamicists fully examined sails back in the mid 1970s .... and still the 'books' and sailing authors pump out all the WRONG stuff! Without tell-tales applied to the windward and leeward side .... and having them ALL flying straight back it is possible to so disturb the flow 'direction' over a sail that the *dynamic* resultant CE (the sum of all dynamic forces acting on the sail) may have moved so far forward (or even moved to several feet in front of the sail) that caused you to encounter such an adverse helm. Sorry but the air 're-circulates' around a sail and the recirculation may have been so 'off' that that caused the extreme unbalanced helm. Even with the sail apparently 'full', such forces can move where intuition tells you they cant possibly be - all depends on the angle of attack, separation (not a stall !!), and where the 'stagnation streamline' approaches the sail, etc. Aerodynamics is definitely not an 'intuitive' science. If you had tell tales on the lee/windward side (at luff and leech) you could have noticed how the flow was along the windward and leeward sides of the sail to verify that you did indeed have correct flow going on. Without tell tales, there is NO way to reconstruct what happened. Just a guess on my part - was that the leech was separated / 'tripped', you had a huge separation bubble at the luff on the leeside, the leeside may have had its flow separated (not stalled) and only the windward side may have been 'working'. You probably had the boom on the centerline instead of dropping the traveller when one sails with mainsail alone, etc. etc. Cant tell without knowing what was going on with the tell-tales. Its actually quite easy to get the (recirculating) flow going backwards if you dont use tell tales to keep things 'straight'. Don Guilette's "Sail Trim User Guide" etc. is *wonderful* means to keep it all SIMPLE and without having to delve into the mysteries of aerodynamics. For those who want to browse into how a sail ***really*** works go to www.arvelgentry.com then go to the 'magazine article section' and explore "how Sails REALLY work" for a better (true) understanding. Caution this is NOT simple stuff; and, if you 'get' it, you'll definitely say ah-HA! Right after you say ah-ha! you will immediately will rush out and apply tell tales to your sails. BTW a H27 will sail quite well solely on just a genoa even during times when you would have reefed; it just wont point as high. You'll need to really drop that traveller down to make it 'go' with just a mainsail ... and need to 'read' those tell-tales. hope this helps.
99% of the sailors and 'sailing authorities' descripitons of how a sail works is WRONG. Bernoulli doesnt apply, the designer's (concept) of center of effort doesnt apply, there is NO such thing as a *slot effect*, backwinding ISNT, .... your high school physics or science teacher had NO idea, etc. etc. etc. etc. All those 'principles' went into the trash can when aerodynamicists fully examined sails back in the mid 1970s .... and still the 'books' and sailing authors pump out all the WRONG stuff! Without tell-tales applied to the windward and leeward side .... and having them ALL flying straight back it is possible to so disturb the flow 'direction' over a sail that the *dynamic* resultant CE (the sum of all dynamic forces acting on the sail) may have moved so far forward (or even moved to several feet in front of the sail) that caused you to encounter such an adverse helm. Sorry but the air 're-circulates' around a sail and the recirculation may have been so 'off' that that caused the extreme unbalanced helm. Even with the sail apparently 'full', such forces can move where intuition tells you they cant possibly be - all depends on the angle of attack, separation (not a stall !!), and where the 'stagnation streamline' approaches the sail, etc. Aerodynamics is definitely not an 'intuitive' science. If you had tell tales on the lee/windward side (at luff and leech) you could have noticed how the flow was along the windward and leeward sides of the sail to verify that you did indeed have correct flow going on. Without tell tales, there is NO way to reconstruct what happened. Just a guess on my part - was that the leech was separated / 'tripped', you had a huge separation bubble at the luff on the leeside, the leeside may have had its flow separated (not stalled) and only the windward side may have been 'working'. You probably had the boom on the centerline instead of dropping the traveller when one sails with mainsail alone, etc. etc. Cant tell without knowing what was going on with the tell-tales. Its actually quite easy to get the (recirculating) flow going backwards if you dont use tell tales to keep things 'straight'. Don Guilette's "Sail Trim User Guide" etc. is *wonderful* means to keep it all SIMPLE and without having to delve into the mysteries of aerodynamics. For those who want to browse into how a sail ***really*** works go to www.arvelgentry.com then go to the 'magazine article section' and explore "how Sails REALLY work" for a better (true) understanding. Caution this is NOT simple stuff; and, if you 'get' it, you'll definitely say ah-HA! Right after you say ah-ha! you will immediately will rush out and apply tell tales to your sails. BTW a H27 will sail quite well solely on just a genoa even during times when you would have reefed; it just wont point as high. You'll need to really drop that traveller down to make it 'go' with just a mainsail ... and need to 'read' those tell-tales. hope this helps.
I disagree
COE does work. If I just have my jib up, I have a forward COE and that causes lee helm. Because I have a fractional rig, when I have as much main up that I should for the wind, then I have weather helm because the main is the main driver in a fractional rig which of course moves the COE back. So saying COE goes into the trash is nonsense. I believe also having the main not trimmed right and having too much pressure on the front part of the boom instead of the middle to back part of the boom will also move the COE forward which will cause lee helm which is what must be happening in this case.
COE does work. If I just have my jib up, I have a forward COE and that causes lee helm. Because I have a fractional rig, when I have as much main up that I should for the wind, then I have weather helm because the main is the main driver in a fractional rig which of course moves the COE back. So saying COE goes into the trash is nonsense. I believe also having the main not trimmed right and having too much pressure on the front part of the boom instead of the middle to back part of the boom will also move the COE forward which will cause lee helm which is what must be happening in this case.
More detail and thanks
Thanks for the great comments. Here's more information. 1. I don't have a traveller, the boom is sheeted over the cabin using three blocks on the boom and blocks on either side of the cabin roof. 2. The boom vang was fairly slack but the outhaul was tight. 3. The boom was out about 15 to 20 degrees off center line. 4. AS I CAME OFF THE WIND, LEE HELM EASED! The higher I pointed, the stronger the lee helm. 5. The water was very choppy, so my speed was relatively slow. 6. I had maybe 15 degrees of heel. I was sailing with guests and wanted to reduce heel as much as possible for their comfort. 7. I was close hauled and there was no strong current.
Thanks for the great comments. Here's more information. 1. I don't have a traveller, the boom is sheeted over the cabin using three blocks on the boom and blocks on either side of the cabin roof. 2. The boom vang was fairly slack but the outhaul was tight. 3. The boom was out about 15 to 20 degrees off center line. 4. AS I CAME OFF THE WIND, LEE HELM EASED! The higher I pointed, the stronger the lee helm. 5. The water was very choppy, so my speed was relatively slow. 6. I had maybe 15 degrees of heel. I was sailing with guests and wanted to reduce heel as much as possible for their comfort. 7. I was close hauled and there was no strong current.
Go with head or main?
In heavy wind, should I go with just reefed main or reefed headsail if I can't go with both?
In heavy wind, should I go with just reefed main or reefed headsail if I can't go with both?
my experiences
Hi Steven, Last fall I did a lot of experimenting on my boat sailing in high (to me) winds. October '04 on the Long Island Sound had winds of 15-25 kts every day (it seemed). I went out one day in 15-20 kt winds with gusts to 25. I sailed with just as reefed mainsail. The boat was easy to sail on a reach. However, when I wanted to go home I found that I could not tack. When I got really close to the wind the boat would just fall off or get head to wind but not through the wind. Then I tried to jibe. I kept the main sheeted in to avoid breaking anything. I found that I could not jibe either (with the main in). Eventually I started the motor and powered through the tack. With just reefed main, boat speed was 3-4 kts on a reach and 15 degrees of heel. The next time I went out conditions were steady 17 kts winds. This time I used full 150 genoa and no main. Boat speed was higher, 4-5 kts, but heeled more (20+) degrees. Again, I could not tack, but I was able to jibe downwind. Next time was steady 20 kt winds. I had my brother with me. We used a reefed main and about 1/2 of the 150 genoa. Now the boat was much faster, at hull speed upwind and surfing faster downwind (3-4 ft swell). The boat heeled more than I liked 20-30 degrees) but the helm was better balanced and we could tack and jibe. What I learned is that for a masthead boat, you need to have at least some headsail up to have a balanced helm. Lee Helm / Weather Helm will develope if you sail on main alone - it just depends on how far you try to turn off wind. My sails are old and in OK condition, but not great condition. If I could flatten the main more I think the boat would heel less. I'm still learning. Hope this helped. Barry
Hi Steven, Last fall I did a lot of experimenting on my boat sailing in high (to me) winds. October '04 on the Long Island Sound had winds of 15-25 kts every day (it seemed). I went out one day in 15-20 kt winds with gusts to 25. I sailed with just as reefed mainsail. The boat was easy to sail on a reach. However, when I wanted to go home I found that I could not tack. When I got really close to the wind the boat would just fall off or get head to wind but not through the wind. Then I tried to jibe. I kept the main sheeted in to avoid breaking anything. I found that I could not jibe either (with the main in). Eventually I started the motor and powered through the tack. With just reefed main, boat speed was 3-4 kts on a reach and 15 degrees of heel. The next time I went out conditions were steady 17 kts winds. This time I used full 150 genoa and no main. Boat speed was higher, 4-5 kts, but heeled more (20+) degrees. Again, I could not tack, but I was able to jibe downwind. Next time was steady 20 kt winds. I had my brother with me. We used a reefed main and about 1/2 of the 150 genoa. Now the boat was much faster, at hull speed upwind and surfing faster downwind (3-4 ft swell). The boat heeled more than I liked 20-30 degrees) but the helm was better balanced and we could tack and jibe. What I learned is that for a masthead boat, you need to have at least some headsail up to have a balanced helm. Lee Helm / Weather Helm will develope if you sail on main alone - it just depends on how far you try to turn off wind. My sails are old and in OK condition, but not great condition. If I could flatten the main more I think the boat would heel less. I'm still learning. Hope this helped. Barry
The odds are with the boat profile!
Your boat has a fairly high profile, with a reefed main the windage and chop could not be overcome at those wind speeds and so you had lee helm. Remember in a masthead rig the jib provides most of the driving force, not the main. So with main only and reffed you could not drive through the chop AND the windage forward. I doubt you would see that effect in lower windspeeds. Wind force times force as speed doubles.
Your boat has a fairly high profile, with a reefed main the windage and chop could not be overcome at those wind speeds and so you had lee helm. Remember in a masthead rig the jib provides most of the driving force, not the main. So with main only and reffed you could not drive through the chop AND the windage forward. I doubt you would see that effect in lower windspeeds. Wind force times force as speed doubles.
when in doubt, let it out...
my first boat was an '82 h27. Typically, when I experienced a lot of lee helm (reefed or not), I would simply let out the mainsheet to spill some wind...just enough to give some steerage. For what it's worth...
my first boat was an '82 h27. Typically, when I experienced a lot of lee helm (reefed or not), I would simply let out the mainsheet to spill some wind...just enough to give some steerage. For what it's worth...
RichH - great resource
I went to the link you suggested and what a great link to wear out your printer. I think I need a new cartridge now. And, it looks like I have many hours of reading to do. I have re-entered your link to give it greater visibility for all to see. If work is boring and the boss isn't looking, download some of these articles and read.
I went to the link you suggested and what a great link to wear out your printer. I think I need a new cartridge now. And, it looks like I have many hours of reading to do. I have re-entered your link to give it greater visibility for all to see. If work is boring and the boss isn't looking, download some of these articles and read.
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