Sail Control question

P

pez

Member
ok... I have the old school vang... I moved the Jam Block to the top position so the jam is at the boom and not at the base of the mast. I've since been able to fully tighten the sucker down as opposed to it just hanging there...

Since then the boat has been, well, slower... Oddly, I also re-rigged the cummingham, and outhaul at the same time.

The laser is my first boat (for all intents and purposes), and I have no sailing experience beyond that...

Vang - the tighter it is, the less power the sail has because it lessens the "airfoil" shape of the sail by lengthening the luff... right? Wrong? Geez I cant believe someone would think that....

Cummingham- Can depower the sail by stiffening the leech, which prebends the mast. What physics are at work here that cause this de-powering?

Outhaul - Can de-power the sail by making the sail flatter. This controls the draft of the sail. The tighter you have your outhaul, the less pressure differential is created by airflow across the sail (shaped like a piedce of plywood vs a airplane wing.

How close am I to understanding this stuff?
 
Vang has more effect on the leach than luff, and it shouldn't matter which block you have where, the attachment points are the same.

Cunningham controls fore/aft location of the roach (the curve of the airfoil if you will.

Outhaul controls how much roach.


Hope that helps you a little
 
ok... most of the time I dont need to depower the sail (not a ton of wind etc)...

I searched around and the "why's" are somewhat elusive. I cant figure out why so many people are paying hundreds for 8-1 purchase vang and a 13-1 cunningham to go sail in 10 kts.

So I am going to throw all that out the window, and use the cunningham to take the wrinkles out of the luff and going to set the vang just to the point where it wont come off the boom... If I need to de-power I will pull in cunninham and vang a little at a time...

I dunno... sorry to sound frustrated, but taking the time to learn a bunch of new knots to make my standard rig perform more like the performance package rig... then realizing that I really dont need all that is somewhat poetic...

Just me $0.02
 
pez

not ragging on you, just trying to put things in perspective.
all things being equal... weight (150 lbs.), skill, boat, windspeed (lets say 15kts.)
boat #1 has updated gear, the other one does not.
boat #1 with updated vang on hard, cunningham & outhaul on appropriately.
boat #2 without updated gear... vang on some, cunningham on some, & outhaul on some.

Boat #2 will undoubtedly get his @$$ handed to him.

it is all about boat speed, boat speed, boat speed.

I also sail a J22 in a very competitive fleet in the southwest. I get my @ss handed to me often, but I also look at what the guys that are winning are doing. Obviously, experience has the most to do with it, but keeping up to date with gear is important. This way I can't blame the boat & must raise my own game to be competetive. It costs, but I compensate by drinkling cheap beer. :D
 
LIFE'S TOO SHORT TO DRINK CHEAP BEER!!!!!! Seriously pez, you are on the right track, and roshambo is too. Boat speed is what it's about, and the ability to control the boat and sail without getting overpowered (re: Cayard on the Volvo Open 70's). All the extra purchase had me a bit confused too, but consider many Laser sailors are small girls and not weightlifters (as an extreme comparison)and you'll understand why!
 
ROFL... Rock on, no worries ragging on me roshambo, I'm trying to encourage discussion here... I'm 170-175 lbs depending on wether it's been a guiness month or a busch lite month... thanks for the advice.

The only control I CANT adjust well is the vang... all I read is that you tighten it to depower... perhaps something that experience will teach me is "why" the vang tension depowers the sail... I have no problems setting the cunningham or the outhaul with the original rigging... even simplified... Sorry, I guess I'm just challenging the notion as to why I need extra purchases on the outhaul, cunningham etc...

I've been vanging like mad, cleating it off and tying two half hitches below the block... I think this is why my boat seems to be slower now. I couldnt cleat the thing before because the boat had improperly sized line in the vang (how I bought it)....Now that I CAN actually cleat the thing, I think I'm over doing it.

So, just as bait for further discussion: WHY does increasing vang tension depower the sail? Whats going on with the sail shape, how should the vang tension be adjusted on a close, beam, or broad reaches? Downwind?
 
Vang tension does 2 things. It pulls the leach tight which bends the mast & to a lesser extent it bends the boom. Both of these actions pull out the extra material in the sail, making it flatter. A flatter sail generates less power than a fuller sail.

If you search the forum there are lots better descriptions from much more experienced sailors than me regarding settings for specific points of sail and wind/wave conditions. I will reiterate that my experience is that keeping the boat flat is the 1st , 2nd and 3rd most important keys to going fast. Roostersailing has some really good stuff on downwind sailing. I had to read it a couple times, go sailing a couple times and then reread it - still can't quite seem to get the hang of catching waves and staying on a wave downwind.
 
pelagic
lol
i am humbled & hate cheap beer, but sacrifices must be made (i also bum good beer when i conveniently forget to bring the cheap stuff)

pez
also think of it this way... when the boat is overpowered & on it's ear, the daggerboard is at some acute (or obtuse) angle (in stead of 90º in a perfect world) to the surface of the water which is least efficient in keeping the boat going in a straight line (it slips sideways).
also there is probably heaps of weather helm & then you arte dragging the rudder through thte water, causing more drag.
flat boat, straighter line, less weather helm... faster
all relating to sail shape.

i promise to drink as little cheap beer as possible

cheers
 
I looked at some pics that we took On a relatively heavier air day, and in most of the shots I was heeled over, but in the shot where the boat is flat, there's a marked difference in the size of the wake...

I notice also too that in the shots where I'm heeled over, the tiller is not neutral, but rather is at an angle to cancel the weather helm as the heeld boat tries to head up.

thanks for the discussion guys, read, think, sail, read, think, sail....
 
I was pondering your question on mast bend... Roshambo could help here w/ his experience on J's probably, but from talking with my Dad (Olson 34), on larger vessels, controlling mast bend and forestay tension, i.e. adjusting the running backstay is key to controlling weather/lee helm. While it may not help boat speed, it can make things more balanced and easier to handle. Since we don't have forestay's to tension and straighten for upwind performance, I'm wondering if it's more a balance adjustment than boat speed adjustment. Gonna have to mess with it some more when we get some decent steady breeze...
 
pelagic

mast bend, or rather mast placement & bend have everything to do with weather helm. Originally J22's (in the early 80's) had no mast rake to speak of. this produced very noticable lee helm (very bad upwind pointing characrteristic). In modern times (anyway since '97 when I got our boat) there is very much mast rake (requiring new fore stay, or 5" to 6" tang to make original fore stay work) thus creating weather helm which makes the boat point better upwind & has much better upwind boat speed.

I digress... we are talking about lasers. sorry about that.
with more vang purchase & a lot of sheet (block to block on the traveler), one is able to effectively change the bend of the mast & center of effort in the sail with relation to the daggerboard. again creating weather helm & probable better upwind performance. where one sits on the boat will also effect weather helm. sitting further forward will better balance the boat & one can really feel the difference in the helm.
i am probably preaching to the choir, but upwind you want some weather helm because the blades will create more lift & one will have better upwind performance. Off the breeze & downwind neutral helm is preferable as you don't want to push the tiller & drag the rudder around & slow the boat down.
it is easy to change the direction of the boat simply by changing body position inboard or outboard.

yikes... must drink less coffee
 
pez said:
I notice also too that in the shots where I'm heeled over, the tiller is not neutral, but rather is at an angle to cancel the weather helm as the heeld boat tries to head up.


exactly!
when you are heeled over as you say, you are pulling the tiller like crazy to get the boat to try not to round up. hence, dragging the rudder around. this is SLOW! get the boat flat & you will notice a more balanced helm.

hike like crazy!
Click to expand...
 
as has been said earlier vang tightens leach and bends mast which flattens sail which depowers the sail. What hasn't been mentioned unless I missed it is that in the laser we vang-sheet in higher wind conditions. This means you have some tension in your vang beyond block-to-block with the mainsheet. Then when a gust hits (you're already hiking hard) you can ease the main without the boom rising (which would add depth the sail and therefore even more heeling force) and keep the boat flat with as much power as you can handle. Any heel is bad, and so is pinching.

cunningham opens the top of the leach and pulls the draft of the sail forward and bends the mast, all of which depower the sail. Old controls I think made it pretty tough to pull on as much cunningham as you might want in a blow, especially from a hiking position. Same for vang and outhaul. In variable conditions you will want to adjust the vang tension quite a bit. But when its blowing hard its fairly critical to ease vang before rounding weather mark and get it back on (along with cunningham) right after rounding leeward mark.

like many of you I mostly sail in light conditions and the cunningham isn't used. But you sure appreciate it when the wind comes up, it makes a tremendous difference in being able to handle the boat to windward.
 
Thanks ro, I thought so. Another tidbit of info I picked up yesterday is to think of the mast as bending forward in the center, as opposed to aft at the top. Kinda helps picture the center of effort movement. Basically all this it to keep the draft (I mis-wrote earlier and referred to this as "roach", which is the curve of the leach) of the sail where it's most effective. It moves aft as the wind increases, so tightening the outhaul reduces total draft, and tightening cunningham moves draft forward.

Pez, back to the purchases... This I hadn't thought of, but having the 3:1 and 5:1 block set-up for the vang provides coarse and fine adjustments, which I understand is getting popular on larger boats these days.
 
pez said:
The only control I CANT adjust well is the vang... all I read is that you tighten it to depower... perhaps something that experience will teach me is "why" the vang tension depowers the sail...
Click to expand...

[Edit: oops -- I see now that Bplaxton already said the same thing before I did....]

Two things.

1. When you're sailing upwind in a breeze, and you're sheeted in tight with not much vang on, watch what happens as you ease the sheet (as you would in a puff). The boom not only goes out, it also goes up. As the boom goes up, the sail gets fuller. So, at the very point you want to ease out and spill wind to depower. you end up making the sail fuller and more powerful. Now try the same thing with a lot of vang cranked on. As you ease the sheet, the boom goes out, but it doesn't go up much, meaning that the sail keeps its flat shape, doesn't get fuller, and spills wind (which is what you wanted to do). So the vang give you much more ability to deal with puffs.

2. The vang bends the mast. Bending the mast flattens the sail.
 
Chris123 said:
[Edit: oops -- I see now that Bplaxton already said the same thing before I did....]

Two things.

1. When you're sailing upwind in a breeze, and you're sheeted in tight with not much vang on, watch what happens as you ease the sheet (as you would in a puff). The boom not only goes out, it also goes up. As the boom goes up, the sail gets fuller. So, at the very point you want to ease out and spill wind to depower. you end up making the sail fuller and more powerful. Now try the same thing with a lot of vang cranked on. As you ease the sheet, the boom goes out, but it doesn't go up much, meaning that the sail keeps its flat shape, doesn't get fuller, and spills wind (which is what you wanted to do). So the vang give you much more ability to deal with puffs.

2. The vang bends the mast. Bending the mast flattens the sail.
Click to expand...

Chris / All -

thanks for the great discussion. Regarding point #1 above, as the boat heels over, and I respond by easing the sheet, it's difficult for me to visualize all the effects of such... there's also a considerable amount of air getting spilled out of the sail because the profile it's presenting to the wind is smaller because it's not perpendicular to the waterline.

The wind forecast for us this weekend is not looking all that great, but I hope to get rigged at some point so I can apply this discussion to some sailing. I'm going to set the vang with the sail head to wind. and just tighten it enough to keep the vang key set. I ordered some new cleats and I'm hoping to have those the weekend also.

I shall report back here with my findings (provided there's enough wind to make rigging worthwhile)....
 
pez said:
The wind forecast for us this weekend is not looking all that great, but I hope to get rigged at some point so I can apply this discussion to some sailing.
Click to expand...

You and me both. I'm not flipping the thing over quite so much these days and I don't drop things anymore on tacks, so it's time to figure out what all the controls do.
 
If it's light, don't rig head to wind; rig as if the boat were on the wind and then just play with the cointrols. Where the Laser differs from many boats is that unless the vang is tight, easing the mainsheet in a gust just makes the main much deeper and therefore more powerful. An old-style vang with the loops we used to use replaced by blocks is powerful enough for most sailors as long as they have good upper body strength.

In a breeze, you will be steering up and down a lot through waves; pinching up wave faces (there is more wind going up the face if the waves are big, there is the radial effect of the water particles according to some people, etc) then bearing away down the back. This means that you need a wider "groove" to steer to (ie the sail shape must cater to a wider range of angles of attack).

By pulling the cunningham on, you pull the draft forward, make the front of the sail more curved, and therefore make the boat more forgiving of the variation in the angle of attack as it changes over waves. This is also something you do in very gusty conditions or anytime it's really hard to stay in the groove; on offshore yachts we often dump running backs when the waves are getting chunky and the driver is having a hard time.

One vital point is that the mainsheet hand should be working really hard in a big wind; in and out, in and out almost all the time, keeping the boat powered up but flat. The Laser is like a rowing boat; the harder you work, the faster you go.
 
just one little point that no-one else has mentioned.....

When its howling and you are needing to depower lots, if you can "super-vang" ie max the vang on until the boom is practically sitting on the deck with no mainsheet tension, a weird thing happens.

The bend in the mast starts to exceed the curve cut into the luff of the sail, which allows the leech to open again, as the sail starts to invert. Suddenly you find that you cant point quite as high, but by dropping just a few degrees off the wind, you go a lot faster, especially if there are waves about.

Also, once the vang is on really tight, it becomes a lot easier to trim the mainsheet, as you are only moving the boom sideways, not up and down.

On the downside, if you stuff up in a tack with the vang on that tight, you can get kinda stuck! remember to duck lots!!
 
So pretty good results this weekend experimenting with the new control settings. I dont really know where I got the impressiong that "cranked down hard" was the best setting for the cunninghame and vang.

I sailed with just enough cunningham to pull the wrinkles out of the luff, and just enough vang to keep the vang key engaged. There was not a ton of wind, but I think it made a difference against the previous weeks sluggishness and frustrations...
 
One article worth noting (and still available from the Rooster site I think) is Steve Cockerill's paper on the Stayless Laser (Style) Rig. Effects of Cunningham and Vang are different compared to effects on a fully stayed rig.

Article also discusses sailmaker targets for the Laser sail and how these affect handling below and above the design wind or in rough wind.

Understanding the different dynamics of the unstayed rig means you know when and what to adjust and the compromises entailed.
 
pez said:
So pretty good results this weekend experimenting with the new control settings. I dont really know where I got the impressiong that "cranked down hard" was the best setting for the cunninghame and vang.

I sailed with just enough cunningham to pull the wrinkles out of the luff, and just enough vang to keep the vang key engaged. There was not a ton of wind, but I think it made a difference against the previous weeks sluggishness and frustrations...
Click to expand...


There are many strange myths in laser sailing. Over tightened cunningham is one, the two-block theory another. Mindlessly sheeting block to block is as silly as not trimming the mainsheet on a reach. But the idea is popular :confused:



cranked down cunningham will reduce your pointing ability. I sail as you've described, with just the wrinkles pulled out of the luff. When things get heavy I use the vang, then the outhaul, then the cunningham as final choice - in that order. You can pull out too much draft with the outhaul though, and that should be obvious because generally you stop dead.

as far as your earlier description of heeling and weather helm, try sitting further fwd to lessen the drag of your wake, sit out more to keep the boat flatter and put telltails on the bottom of your sail batten pockets as a guide for mainsheet trimming.

Your wake should be clean and flat, not bubbling around the trailing edge of your rudder blade. Most people tend toward a slight leeward heel. Try to train yourself to stay flat, that will reduce your weather helm. The telltails will show exactly how much mainsheet you can ease, and when you're over trimmed, then you won't be heeling or swimming.
 
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