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Lightning Class Association
HomeDownpowering For Speed

Downpowering for Speed — Upwind in 20+ mph

Tim Healy, 1997 North American Champion

We have 9 controls to depower the Lightning when the breeze blows hard, 20+ mph. These controls are:

  1. Backstay, which flattens the main, opens the main's leech and controls the headstay tension.
  2. Traveler to windward/leeward, which controls the boom position to windward/leeward without adjusting mainsheet tension or affecting the leech.
  3. Traveler height, which controls the leech tension without adjusting the mainsheet tension.
  4. Main and jib cunninghams, which flattens the sails and pulls the draft forward.
  5. Outhaul, which flattens the main and opens the leech.
  6. Jib halyard, which controls the tension of the jib wire and can affect the rake of the mast.
  7. Jib lead position, which controls the depth in the lower half of the sail and affects the jib leech tension.
  8. Vang, which controls the leech tension of the main.
  9. Centerboard, which controls your weather helm and your pointing ability by moving the center of resistance and by adjusting the amount of lateral resistance.
At 20+ mph of wind speed, the backstay should be pulled on about 75% of maximum, which will flatten the sail and open the upper leech. The backstay is used to tension the jib wire and remove jib halyard sag. This is a key adjustment to flatten the jib. When it's blowing 20+, flatter is definitely faster.

You should keep in mind that the jib wire acts as your headstay. This means that the jib wire is taking the load created by the sails and the backstay. Upwind, the headstay is used primarily as a gauge to determine the proper amount of jib halyard tension and mast rake. The amount of headstay that is snaking through the snaps of your jib can be a quick reference for tensioning the jib halyard. You should put marks on the jib halyard track for accurate fine-tuning of your tension. If you use the jib halyard alone to tension the jib wire, the mast will be pulled forward and the rake will be thrown off.. With this in mind, you should tension the jib halyard up to the point where the headstay goes slack. The backstay can now be used to tension the jib wire.

If the mast has too much pre-bend (more than 1" at the deck), it will be too flexible and the backstay will not effectively pull the jib wire tight. If the mast is set-up with the proper amount of pre-bend (3/4"-1"), the mast will be stiffer making the backstay more effective in tensioning the jib wire.

One of the side effects of pulling the backstay hard is that the draft in the mainsail moves back. Tensioning the cunningham moves the draft forward. When it gets windy, you should pull the cunningham on hard. You can't have too much cunningham in heavy air. The outhaul should be pulled close to the maximum in order to flatten the lower half of the main and to open the lower leech.

The traveler should be set somewhere between 3/4 and all the way to leeward. Its height should be lowered to set the main leech tension. The objective for your sail trim is to get the mainsheet between 1/2"-1" from being two blocked. This allows latitude for you to trim the main a little more for more pointing.

The jib leads should be back about 1". This flattens the lower section of the jib slightly and makes sheet tension less critical for the leech. The upper leech automatically opens up during big puffs and then returns to its original setting.

The vang should be pulled on tight in these conditions, but you must ease it before the weather mark so that the boom does not bend or break. Upwind, when the mainsheet is eased for unexpected gusts, the vang helps maintain leech tension. On reaches, the vang should be played constantly, off to relieve weather helm in the puffs and on to power up.

When the wind picks up to 23–25 mph, the sail trim needs to be at maximum de-power. The backstay should be pulled on as far as you can pull it without inverting the sail. This means that the mast should be bending so much that the shape of the sail has been almost completely pulled out. If the backstay is pulled on too much, the main will invert and develop inversion wrinkles which cannot be pulled out with the cunningham. When this happens, slowly ease off the backstay until the wrinkles disappear.
Remember, in these heavy air conditions the mast should be blocked no further than 1" forward of the neutral position at the deck. The lowers should be tensioned to 29 on the Loos Gauge. If the mast is blocked further forward than 1", or the lowers are too loose, inversion wrinkles will appear sooner as the backstay is pulled tight.

As the wind builds to 25+ mph, the jib leads should be pulled back 2"-3"+. This depowers the jib and allows the top of the sail to twist open in big puffs. As the wind increases, the jib lead should be moved back more. The jib leads should be pulled back when the main has to be eased out frequently for periods of more than a few seconds. This helps give the boat a wider groove and makes the main trim less critical.

The goal in trimming your sails in big breezes should be a flat main with an open leech and a flat jib with an open leech. The traveler should be all the way down to leeward and lowered close to the deck. The boat should able to be steered through the puffs and waves without making macro-adjustments to any control.

If the boat is still difficult to keep in the groove, raise the centerboard a few inches. This is measured from the stopper pin on the board to the top of the trunk. When the centerboard is pulled up, it pivots on the centerboard pin and the bottom of the board moves in an arc towards the aft end of the trunk. This means that the bottom tip of the board is moving almost directly aft in the first inch or two that the board is pulled up.

When the board is moved back, the center of resistance moves with it. The center of resistance is a point on the centerboard where the sideways resistance can be focused. The center of effort, on the other hand, is the point in the sail plan where all the forces created by the wind and the sails can be focused.

Most Lightnings are set-up with the center of resistance forward of the center of effort because the boat goes faster with a weather helm in light to moderate conditions. This means that we must be sure that our centerboards can reach the maximum forward position (angle of dangle) and our mast butts must be forward to facilitate a healthy amount of mast rake. Because of this, the boat is difficult to control in 25+ mph of wind speed. The board should be pulled up when the main sheet is being adjusted constantly and the helm is changing from extreme weather to extreme leeward helm.

A secondary consideration to the movement of the center of resistance is the decrease of exposed surface area of the board. Lightning centerboards are enormous and giving away some of that exposure in heavy air is good. It reduces the feeling of tripping over the board when you are hit by a surprise puff or wave. Raising the centerboard relieves excessive weather helm and gives the boat a wider groove. The centerboard should come up only when all other depowering techniques have been exhausted.

When you have a better understanding of how to depower for speed, the next windy day will be more successful and, above all, more fun.



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