Downwind max vang setting (keyword - Lee)

C

Chainsaw

Brmmm Brmmm
While I was having a look round the DrLaser archives I found a setting recommended by Mark Jacobi in 1999. To find the maximum downwind setting for your vang, you push down on the boom end by six inches from a loose rest position. You reset your vang to that maximum loose tension and it's set for maximum bang for your buck when entering downwind and by the lee in light to moderate winds. Soon as wind gets crazy, he recommends tightening an inch or two.

What do you think of this idea?

Is it the "industry standard" and it's just me that has never heard of it? LOL :D

I always did mine by eye/feel and while it is now "locked" in position, I don't actually know what distance from rested it is in inches. Will go have a look.

Also, what happened to Mark Jacobi? Did he make it to the Olympics? Did he win? Is he still around?
 
Marc is still very active racing a variety of boats and giving back a lot via coaching, especially at the High School level. He can be found always at or near the top of the Cedar Point frostbite fleet, and is especially fast downwind in all conditions..

In some of his post racing debriefs ar Cedar Point, the settings above are his starting point, but he does the fine adjustment based on making sure the leech is able to flick
 
I've used his suggestion for a couple of years now. Seems to work nicely. Every now any then I think the leech is a bit tight in extremely light air, but I think that's an illusion based on sitting in the cockpit. Everybody I sail with thinks the sail looks good from outside the boat.

Cheers,

Geoff S.
 
Let me get this straight: You push the boom down about 6" from its resting position, pull the vang on snug and then mark the line where it enters into the vang block.

When you set the sail for your downwind leg (ie sailing by the lee), you only let the vang out until you get to that mark on the line.

Correct?

I've always assumed (and made an ass out of myself) that in light air, you just let the vang out all the way. What your saying is that I need more tension on my vang for my down wind legs. This must be the reason I havn't won any races.
 
hmiller said:
Let me get this straight: You push the boom down about 6" from its resting position, pull the vang on snug and then mark the line where it enters into the vang block.

When you set the sail for your downwind leg (ie sailing by the lee), you only let the vang out until you get to that mark on the line.

Correct?

I've always assumed (and made an ass out of myself) that in light air, you just let the vang out all the way. What your saying is that I need more tension on my vang for my down wind legs. This must be the reason I havn't won any races.
Click to expand...

that's pretty much it!

I measured mine and found that it locked at the "at rest" position. That translates to about 2" too much slack as measured along the diagonal of the vang,

and roughly 22 1/2" more rope to pull at the loose end of the vang,

and 6" more hieght than recommended at the clew end of the boom.

The "at rest" position is what I always considered to be "letting the vang all the way off"

It may also account for overpowering/weather helm blips during by the lee sailing - which was concerning me. No wind today so can't try it out. Things will certainly look "tighter" from the cockpit. But as geoff s says, it must look fine from outside the boat.
 
I pulled my vang in so the boom went down 6" from the "at rest" position and put a mark on my line. It ended up being about 18" of vang line. I'll be at regatta over the weekend and we'll see if this makes me any faster.
 
Seems pretty tight to me for light air. I will try this as well at my district regatta this weekend. Our weather report is for 5 to 10 so might be perfect conditions to test.
 
6" down from rest is way too tight for me. I did a bit of experimenting today (15 - 20knots) and managed to get away with a bit more vang on all the time. Soon as i finish lunch I'll go find out exactly how much it is.

What were everyone else's results?
 
I tried the Jacobi method of marking/setting the vang this past weekend and it worked great on my downwind legs. I was able to s-carve all the way with no sense of instability and I was able to catch the wind on waves both BTL and broad reaching. Big improvement over guesstimating.
 
I also agree that Marc's guidelines are an excellent rule of thumb, though my recollection was that Marc told me 4 inches, not 6 (at least I've always eyeballed it closer to 4). As I recall, Marc developed those guidelines long before the advent of the new vang and in those days (which now seems like so long ago) it was not common to attempt to adjust the vang while sailing downwind.

In recent years when I have gone to major regattas I have noticed that the top sailors seem to have their "max ease" setting to be much looser than this. In fact, it often seems that their vangs, while the boats sit on their dollies, are quite slack (as opposed to slightly tensioned as with Marc's guidelines). When I ask about this the general response seems to be that the top sailors are playing their vangs quite a bit on the offwind legs and the slacker setting gives them more range to play with (although it does seem to me to limit the max tension you can apply while sailing upwind but I guess that is a different story).

So... what are the guidelines they employ? Well, mostly experience I'm guessing but I've been able to divine two rules of thumb that make some sense to me: watching the "action" on the upper leach of the main and (easier for me) watching the angle the top batten makes with the boom. I can't get the hang of the first one, I think you are supposed to look for the upper leach moving too much in the waves - you tighten the vang just enough to allow "some" play but not too much. Sort of like determining how long a piece of string is.

On the other hand, I can get behind the upper batten rule. I am not convinced that you really want it parallel to the boom all the time, but it is the sort of reference point that I can understand and relate to.

I think if you are going to win a Laser Worlds then you are going to be so highly trained as to really feel when the vang is too tight or too loose (e.g. too much power on the turn up while carving waves downwind), or maybe not the right amount of power on the turn down... I am not sure. Until I win the lottery and am able to sail 7 days a week I'll probably never know.

In the meantime I like the upper batten angle a lot.

Tracy
 
This past weekend I tried it.

It seemed way to tight... But I normally dont do well in light air and i ended up with pretty decent boat speed downwind.

I am going to try it this Wed night racing and I have another D15 regatta in Austin this weekend.

So I am not quite a believer yet... but willing to keep trying it.

My buddy likes his off in lighter air for when you are by the lee you can sort of roll the boat and trim a certain way to catch the wind twice. Although this does sound illegal and like kinetics it can be performed stealthly and very subtle. In order to do this though you need the vang off and turn the leach into the luff. So maybe having a marking showing where the 6 in or 4 in (your preference) settings are at.
 
As always, Mike Johnson (from the Seattle Laser Fleet) writes some great articles. Relevant to this thread, check out his latest article on downwind sail trim on the slf website where, among other things, he talks about the vang setup.
 
This from the same site as Tracey links to:

Andrew Vance in his article: Downwind Technique
...

5) Vang tension - Loose always!!! I have to bend my mast a little to put the vang tang in the boom on the dock. When sailing I have about 4" of line hanging out of the cleat. The leech should always be elastic/springy, the only time the vang comes on is when there is bumpy chop and you need to stabilize things a bit. This is the setting for downwind sailing in 0-30 knots. NO VANG NO VANG
Click to expand...

I think an important distinction that needs to be recognised when setting up is that these “final settings” will appear looser when the sail is under load, and “tight” when the boat is still sitting on the trailer. Notice he says the mast will have a bit of bend in it, even though the setting is called “Loose, NO VANG”.

It’s a good reminder that the upper mast of a laser is pretty flexible.

This became apparent when I was experimenting with Mark Jacobi’s 6” rule – which I found to be tight in both situations. This over tightness could have some relation to my outhaul max setting. Max outhaul looseness is regarded by this Seattle crew as 9”- 10” from clew eye to boom fairlead – based on Olympic winner’s settings.

In any case, things are getting well within the ball park, and after reading all this and viewing this again:

http://video.google.com/videoplay?docid=4270530856689008464

from the Mike Johnson article, I can see the key, as Tracey says, is the alignment of the top batten to perpendicular to the boat centreline. Then the max boom angle is dictated by that.

So there’s enough here to make some good progress on. I’ll enjoy passing you all downwind like you’re standing still at a laser worlds some time in the future! :p
 
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