April 23, 2012

Sailing Upwind in Choppy Conditions

Waves. They are our friend downwind and our enemy upwind. They add another layer of technical skills and it’s little wonder that waves separate the fleet very quickly. Anytime you are sailing far enough from shore, or in a sea breeze, we are exposed to waves. The size of the waves often determines the type of rig set-up. Although the Laser has a simple rig, we still have the ability to pull a particular shape into the sail. For example, in flatter water, we may want a flattish sail that is set up for low drag and to control whatever the wind strength is. However, in choppy water, we want a sail that is more forgiving to changes in steering angles, but still has enough ‘torque’ to push through waves upwind. The sail will look (and feel) very different for 8 knots flat water compared to 8 knots choppy water. So here is a clue straight away…..ask yourself, are you setting the sail for flat water or for choppy water? Well now you have to have a definition of “choppy water”.

I think the definition of chop is when going upwind, that the waves either make you change direction (by slapping the bow away) or slowing you down (by slamming into the bow). Either of these situations is damaging to speed and height and we now have to steer more aggressively around the waves. But now the rig must accommodate this extra steering range. It must be broadened in its ability to be efficient both when (momentarily) high and low. How? Add more depth to the entry. That is Cunningham. Most people are reluctant to use this as we associate it with depowering on a windy day. This is true. So we need to apply just enough Cunningham to add entry depth, and no more. Similarly, we use soft vang to achieve the same result. A straighter mast also means a deeper entry so we make sure we are not too hard on the vang in winds less than say 12 knots. With a softer vang, we now have full control of sail shape with mainsheet tension alone. It becomes very simple. In bigger waves, ease a touch of sheet. This straightens the mast, adds depth and power and relaxes the leech a little. Perfect for finding that extra punch in bigger waves on lighter wind days. As the wind strength increases, just add more and more downhaul and vang in equal portions.


It is not easy to quantify the above amounts, but is intended to give you a guide as to what you should be focusing on for best rig set up to match the wave conditions. It is not appropriate to produce a similar guide for downwind as waves are largely sailed in a technical way where sail shape is not the major factor.

Now that the rig matches the wave conditions, all that is left is to steer correctly. I can hear you asking the question now, but this is best left to another time!!

10 comments:

  1. Brett, excellent information! Thank you so much for sharing...Pam

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  2. Control settings in the different conditions are something I find hard to really figure out. Expecially, as I get most advices from standard sailors and I sail the radial.
    Well, I would love to ask a bunch of question to every single detail, but my biggest concern goes to the vang. What do you call "50%" vang, or what "non at all".

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  3. Brett's Response:

    There is not a great deal of difference from Radial to Standard Rig set-up. There are some subtle differences but not enough to warrant a discussion here.
    50% vang is really what other people may call, “mainsheet tension vang or block to block vang”. That is, vang is tensioned just enough to take the slack out of the vang system.
    This amount of vang tension doesn’t change sail shape once the mainsheet is block to block. Sheet tension alone is doing all the mast bending, leech tensioning and therefore sail shape work.
    This 50% vang will only begin to have a function once sheet is eased and is a good ‘backstop’ once sheet is eased past block to block tension.

    More that this 50% vang will progressively change sail shape past what mainsheet tension alone can do.

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  4. Thank you, but I am still confused: if 50 % vang is block-to-block, what then is "DON'T USE VANG"?

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    Replies
    1. Brett's Response:

      “DONT USE VANG” is just a reminder to not use positive vang. That is, not more than 50% or more than block to block vang.
      Over-vanging in light winds and bumpy water can really hurt, especially if your steering groove is wandering around a little.

      Delete
  5. Thank you for the detailed explanation that helps me quite a bit especially as you are perfectly right about the estimation of my steering groove...

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  6. So would you say that block to block, take the slack out is the minimum vang setting for upwind? Never less?

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    Replies
    1. I think that's what Brett means for up to 15 knots. But he's tall and most people will be overpowered before that. The vang depowers the rig, so use it when you need to. I've talked to some world-class sailors who play the vang so much in the 10-15 knot range that they have to replace the line every few events.

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    2. Right. That makes sense. My confusion in more in the 0-14 range... in the laser tuning guide it says to sheet block to block and take the slack out for 0-5.... and then when the wind increases, ease the vang to be taught at one foot apart. Goodies book says in light wind to take up the slack about a foot apart also.

      From what I gather from you and Brett, min. vang should be block to block and take the slack out for the super light, then, in more breeze, you should be almost block to block anyhow and the vang isn't doing much, then use it for vang sheeting/flattening in progressively higher winds.

      I'm trying to figure if there are a couple schools of thought and which is better or which requires a different style/technique etc. or if everyone does the same thing at a higher level with the vang and maybe it's not being explained well or my brain isn't processing it well!

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    3. As a rule (for me) the vang is loose at the design wind speed (10-12) and tighter outside this range. I never have a block-to-block vang in light air (see the pic and discussion here http://www.impropercourse.com/2012/05/laser-cheat-sheet-smart-settings.html).

      For light to medium conditions, people will use different settings and get the same results. When the wind picks up, the front pack tends to set up the same and then it's all about fitness.

      Delete

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