Sailing by the lee

M

macwas16

New Member
Today I got out on the water a bit and tried sailing by the lee for the first time. I must say its fairly awkward the first time and even a bit scary with the boat lurching and stuff like that but overall it was good even though my mainsheet was a bit short to get the full effects. I don't really have too much more to say, I just wanted to get some talking around this here forum...very very slow lately. Feel free to add any comments or suggestions, I always like that. Oh well, happy sailing :cool:
 
yeah im workin on sailing by the lee too. dont try it in heavy air till you're pretty good in light and medium air. lol learned that one the hard way ;)
 
Thanks Mac. I'd appreciate a discussion on by-the-lee too. I've read all the articles, seen the on-line videos and had a few goes myself but I think I'm missing something as I son't seem to be going any faster than the other guys just being "pushed" dead down wind. None of the others at our club seem to use by-the lee - at least they don't seem to be "zig-zagging " down wind. We sail on a river which is only about 150m wide and so don't have waves to surf although we do get up to 25knot winds.
I've only been sailing 8 months so still learning everything and I find some of the discussion articles use terms that make it a bit hard to follow - what I'd find really helpful is a plan view of wind/boat/sail configurations most appropriate for using by-the lee. I'm sure I've had it running correctly a few times with the telltales running in reverse and mast mounted wind indicator spinning but I don't feel confident enough to get it set up right every time - or that its giving me any advantage.
 
In light winds you only feel the advantage when you go really deep. I was lucky enough yesterday to have a huge lead downwind on the last leg so i did some experiments. It was windy enough just to get planing on a reach but not in any other direction. When I sailed by the lee really deep I was going fast enough to catch waves. The speed increase alone is not huge - to get the advantage you have to use that extra speed to eiher get planing, get surfing waves or use the extra freedom of direction to get in more favourable current (or less adverse current) or break cover/wind shadows or get into a more windy area. In strong winds a broad reach is faster and the angles can be narrower.
 
Thanks Will - you're a stalwart of this forum and I appreciate reading your posts.
But, for me at least, can you explain your terms a bit clearer. By "deep" I presume you mean at a relatively large angle to the wind instead of straight down wind. I've read that for by-the-lee sailing the angle with respect to dead down wind increases as the wind strength decreases and you seem to be saying the same.
You also say that "in strong winds a broad reach is faster and the angles narrower" - this seems to be in the same vein as the first point, but in these strong winds, if the aim is to go straight down wind, would you still alternate between bythelee and broad reaching ? Or are you making a distinction here for broad reaching ie the sail would not be out past the mast ?
This is a general question I have with regard to BTL, do you always let the sail out past the mast or is this angle also influenced by wind strength ?
Finally, when "zagging", ie moving from BTL (with the wind coming from the lee side of the boat - the "zig") to a broad reach, do you adjust the sail in from past the mast ? One thing I have learned is how to death roll and I'm now wary of letting the sail out too far when going down wind.
 
Sailing in winds over 18 knots, a great lifesaving technique on a run is to turn down by the lee with the boom in a good bit in from abeam. Much more stable than dead running and faster than a very broad reach in the other direction.
 
In reply to Alan Benn's post:

You assume correctly about "deep". In light winds the angle between your by the lee course and a dead run can be large (up to 35º ish) and as the wind increases this angle can get smaller because you won't have to go so far off the dead run to get the speed increase. Obviously if you are trying to get to the leewrad mark and you can do it fast with a narrower angle that is more preferable as you sail a shorter distance. In strong winds I would say sail a dead run or sail a broad reach and gybe. If you take the gybe option think about wind shifts - you should try to be on the tack taking you closest to the leeward mark.

Sail trim by the lee is actually quite simple - imagine how you trim the sail on a reach and reverse it! Because sailing by the lee establishes laminar airflow instead of just the wind pushing you trim the sail in reverse to a reach. By this I mean let the sail out and pull in until the leach starts to flap, then ease out a bit. You want it just a bit further out than when the leech flicks.

When you broad reach you should have quite a loose kicker so the leech is twisted. This means that you can afford to have the boom quite far in (60-70ºish to the centreline) which will prevent the top of the sail passing in front of the mast. The aerodynamics of why a twisted sail works well in relation to the average sea wind gradient is very complex - just take my word for it.

Stability is governed mainly by kicker (vang) tension and daggerboard position. When you get moving the board will help prevent rolling and tightening the kicker reduces sail twist so the top part of the msail does not start to produce 'windward' lift. Therefore more kicker = more stability but less speed (less sail power) and more centreboard in the water means more stability but also increases drag. At the top mark you need to ask yourself the question:

"How much speed do you want to trade off for stability?"

As ever this is sailing being full of risk assessment. To much stability and and fleet will cruise past; to little and you'll swim, while the fleet sail past. I guess it all comes down to intuition and experience.

Obviously, the more you practice, the more informed your guesses will be.

If when practicing sailing by the lee in moderate winds you don't capsize; you are not taking enough risk and not sailing fast enough!

In reply to Foo Barstow's post: sailing by the lee with a trimmed in sail is what everyone else calls gybing!
 
If you want to find out more, send me a "private message" or e-mail and I can attach a PDF file to a reply. This PDF explains everything you need to know...
 
Will Wrote: "In reply to Foo Barstow's post: sailing by the lee with a trimmed in sail is what everyone else calls gybing!"

Ripped from the Rooster site - if you back off the vang (so the luff, which is really the leach in this case) is in still in front of the mast when you sheet in a bit from abeam, you get good reverse flow without the worry of being blown over to windward. After reading this I tried it the next time it was really blowing and it is more stable and seemed to be faster than a reach of comparable angle. May not be the ideal way to get down wind, but it beats swimming for those who can't control a windy run. And because you have little vang you have a responsive sail in the waves.
 
Can you get too 'deep' when you're sailing by the lee? If so, is there a trick to knowing when you are too 'deep'? Or is how 'deep' you get depend the sailor and common sense?
 
I believe the answer to the "too deep" question is simple: look at the tell-tales (just like any other point of sail). As long as the tell-tales are pointing toward the mast there's good flow over the sail. In that case, one can try sailing a bit deeper and see if the tell-tales stall (remember that sailing deeper means "heading up"...).

If you're feeling lucky, you might be able to sail a bit deeper while keeping reverse flow over the sail by sheeting in a bit (but see the "we call that gybing" comment above...). So long as you have a good positive angle of attack between the wind and the leading-edge of the sail (i.e. the leach), you shouldn't gybe...

Cheers,

Geoff Sobering
 
I have a tactical question about using sailing by the lee. It's often true that one leg of a triangle course is deeper than the other. In cases when one is a broad reach, it is a good idea to try and sail by the lee on that leg?

If the second leg is the deeper one, then it's easy to get by the lee just by not gybing at the gybe-mark. It seems tougher to get by the lee if the first leg is the deeper one. Is it beneficial to hold a bit high after rounding, then dive down, gybe, and return to the rhumb-line course to the next mark with the boat sailing by the lee?

Cheers,

Geoff Sobering
 
No gybing at the gybe mark is an amzing strategy: you stay on starboard (assuming marks to port) throughout so the inside overlap rule (RRS 18 etc) is not applicable - you can sail where you like.

How deep you sail is nothing to do with sail trim. You can sail a laser on a beam reach by the lee. However, how deep you go is governed by:

Tactics
Strategy
Boat Speed

Tactics and strategy are self explanatory as to why you might want to go deep (break cover or get into favourable wind/current.) etc.

If you have done any assymetric spinnaker sailing you will know how to judge the angles: deeper in light winds, closer to a run in stronger winds etc.

In moderate winds you can go quite deep to get the boat to plane then as you start to plane in a gust come back towards a run to make ground towards the mark. As the wind strength increases you can plane on narrower angles so deeper angles are pointless. Once the wind is strong enough to plane straight to the bottom mark just point the boat at the mark and hold on tight!
 
Reply to Geoff who said ...
"If you're feeling lucky, you might be able to sail a bit deeper while keeping reverse flow over the sail by sheeting in a bit "

When by the lee, the deeper you try to go, shouldn't you be letting the sail out more rather than sheeting in ?
 
> When by the lee, the deeper you try to go, shouldn't you be
> letting the sail out more rather than sheeting in ?

That depends on your definition of "deeper"...

Once you're by the lee, "falling off" (i.e. pulling the tiller away from the sail) is actually turning you away from dead-downwind (i.e. higher onto a by-the-lee reach). In that case you do want to let the boom out to maintain the correct angle-of-attack between the wind and the sail. Conversely, if you "head-up" (i.e. pushing the tiller toward the sail) you're actually turning toward dead-downwind, and you need to pull the sail in to maintain the correct angle-of-attack.

It's the latter situation that I was refering to when I said you need to sheet in to sail "deeper".

I've tried to create a diagram to illustrate this:

http://www.mailbag.com/users/sobering/ByTheLeeDiagram.gif

The wind is coming from the bottom of the page, and the two sails are at the same angle relative to the wind (i.e. same angle-of-attack).
The boat on the left is sailing dead-downwind, while the boat on the right is reaching up.
Note the angle the sail makes relative to the boat.

I hope I got this right (if not, I'm sure someone will correct me...), and I hope the description/diagram help...

Cheers,

Geoff Sobering
 
Reply to Will who said:
"You can sail a laser on a beam reach by the lee."

I would have thought that by the time you got to a beam-reach, the distance between the center-of-effort (CE) of the sail hanging out over the front of the boat and the center-of-lateral-resistance (CLR) at the centerboard would give you tremendous lee-helm.

Aerodynamically, it should be possible; I know I've sailed Stars with the jib in the whisker-pole (same reverse-flow situation) well up on a beam reach before having to swtich back to the "normal" sheeting arrangement.

Cheers,

Geoff S.
 
Reply to Geoff RE: "deeper". Yes I see what you're saying Geoff and sorry I din't take notice of your first post where you specifically said "deeper" means "heading up". But then I was going on an earlier post from Will where I asked about what deeper means to him and its the opposite to what you say ! I'm not going to start another debate here, there are enough of those (-; , all is clear now.

I have sailed "more downwind" as you suggested with the sail sheeted in and noticed the reverse flow - its my standard beginners/cowards tactic for staying upright in stronger winds as well as dropping the centreboard.
From all the advice here I plan to startletting that sail out more and bearing off to stay on by-the-lee but get more sail out.
 
My bad...

Reply to abenn who said:
> Reply to Geoff RE: "deeper". Yes I see what you're saying Geoff
> and sorry I din't take notice of your first post where you
> specifically said "deeper" means "heading up". But then I was
> going on an earlier post from Will where I asked about what
> deeper means to him and its the opposite to what you say!

My bad; sorry 'bout that... I'd forgotten about the earlier post defining terms. I have to admit that I've gotten to the point where my mind sort of reverses itself when I get by the lee and I just think in terms of reaching and running (with the appropriate reversed tiller/trim motions)...

Cheers,

Geoff S.
 
Question prompted by will's comment:
> When you broad reach you should have quite a loose kicker so the leech is twisted. This means that
> you can afford to have the boom quite far in (60-70ºish to the centreline)

Can someone describe in specific terms how much to ease the vang? I don't remember seeing a good description in any of the articles (but I may just be forgetfull...). Something like the amount of twist in the sail, boom height above perpendicular to the mast, or similar. A pointer to one of the articles would be great.

Cheers,

Geoff S.
 
When sailing downwind, tightening the vang/kicker is tensioning the leech and reducing the sail twist. When reaching sail twist is useful because the mast top wind speed is higher due to air moving slower at the surface. This means the apparent wind at the top of the sail is blowing from behind the angle of apparent wind at the bottom. This means you want the bottom sheeted in more than the top - this is what leech twist achieves - it ensures the whole sail is at an optimum angle of attack to its local apparent wind. When sailing downwind on a run, there is no laminar airflow so leech twist in itself is not exactly important, the more important factor being leech tension. A tight leech "hooks" the leech to windward which makes the rig more difficult to steer and the amount of aerodynamic lift acting backwards increasing. This means your induced drag is going to increase.

From a sailing by the lee perspective a tight kicker is still a disadvantage. We want a loose leech to allow undisturbed entry airflow. A loose leech will also flap more which will help pump air across the foil. The only sails used on "normal" bermudan rigged yachts with a truly soft entry edge (no mast or wire) is the spinnaker. Who has seen a spinnaker with a straight leading edge? Even assymetric spinnakers for reaching and light winds (on yachts eg IACC boats) have a great deal of curve on the leading edge.

I can't tell you a good boom/mast angle because I do not know - I just let my kicker all the way off and then cleat it. The trick is to practice and see how much you can reduce kicker tension before the boat becomes too unstable. (You have to be the judge of how much is too much...)

In my opinion , once the wind picks up to and above marginal planing conditions, there is too much else to think about then fine tuning the kicker. (Catching waves, gusts, stabilising the boat, tactics etc)
 
Reply to Will who helpfully said:
"I just let my kicker all the way off and then cleat it."

That's *exactly* what I wanted to know! It gives me a good starting point. I'll try it next time I'm out [in non-nuking winds...].

Also thanks for the info. on twist by-the-lee. It seems that there's really no "magic", just the same basic aerodynamic/sail-shape principles.

Cheers,

Geoff S.
 
Go deep! start by bearing away till you are 15-25% apparent wind by the lee --

I got a cheap flag-style mast head fly that I slip inside the front of the sock at the top of the sail to see how deep I am

when you switch from btl to reaching, turn big and sheet in.

rule of thumb is not to let the boom forward past 90%

let the vang off

its ok to leave the board down pretty far -- its stable and arguably not slow

see Rooster Sailing tutorial titled "the fourth dimension"

-- David
170143
 
Now I've got some more dumb questions about vang-tension again...

I was out today practicing in choppy 10 kn conditions. While rigging I checked my vang setting against the suggestion in the drLaser article "Ideal Vang Tension Downwind" (in the boat handling section). Mark Jacobi (the author) suggests setting the vang so that at it's loosest it pulls the end of the boom down 6 inches from the vang-disconnected position. My vang setup will allow more ease than that, but I noted where that spot was and went sailing. My first impression was that "6 inches down" is a fairly tight vang setting (that's about where I've been sailing down-wind); there was fairly little twist in the leach of my sail when sailing by-the-lee. I had to ease the vang another 6 inches (boom end) in order to get noticable twist.

First dumb question(s): Could I just be mis-reading the amount of twist in the sail? Was the "6 inch down" setting probably giving me about the right shape? Could the fact that I'm using a less-than-new sail be part of the problem?

Some observations:
First, the sail did pump around quite a bit most of the time when I was sailing with the loosest vang setting (remember it was pretty choppy, esp. relative to the wind strength). I'm not sure if it was faster (I was out alone), but it did appear to allow me to sail a bit lower (closer to dead-downwind) than the "6 inch down" setting.
Second, when I wanted to reach-up to a broad by-the-lee reach (ex. to surf the face of wave), it felt like the tighter vang (along with a more eased boom) was better (faster, more-stable).

Are do these observations sound typical? Should I practice more with the eased vang and broad reaches?

Cheers,

Geoff Sobering
145234
 
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