29 September 2008

sail trim for beginners

The following holds for Albacores and Lasers unless specifically aimed at one of the two.

  1. Fine tuning of sails is not very important for pleasure sailing and even not very important in racing unless you are at the top of the fleet. Just make sure that every line is attached, especially the halyards should be well-secured, the outhaul should hold well and that's it.
  2. The most important sail control are of course the sheets and before you think about tuning, make sure that you always sheet perfectly, watch your tell-tales and play the sheet to find the point where the sail draws best. Especially in light winds where the wind is coming from many different directions at different times, it's more important to catch that wind than to tune the boat.
    Also, depowering the boat in high winds is done first of all by letting out the sheets. Only when the sail starts backwinding a lot will the pleasure sailor need other means of depowering.
  3. Most people see the boom-vang (or kicker) as a means of depowering the boat upwind, but that's actually only one of its job and maybe not the most important one. It is true that vang is only needed as the wind increases, but it is entirely false that vang is only needed upwind. And here's why: as the wind increases, it pushes the middle and upper half of the sail forward, thus lifting up the boom (especially when the sheet is not close-hauled!). This twist in the sail means that the upper part is let out far more than the lower part and consequently at least one the two parts is not drawing well (either the lower part is choked or, more likely, the upper part is spilling air). Since the twist of the sail changes with every little puff and maybe also with waves, this makes the boat very hard to control. It feels like you have to correct sheeting, steering and hiking all the time. Unstable. That's where the vang comes in: you pull the boom down until the top batten in the sail is parallel to the boom again, not twisted out at the leech. In this position the sail has optimal shape, draws perfectly (as long as you sheet it correctly, of course), the boat becomes stable again and you go actually faster than using no vang! That's one of the most important lessons I have learned this year!
Pleasure sailing in not too light to medium winds (Laser and Albacore):
  1. (Albacore only) Before you even hoist the mainsail: make sure both sides of the rig tension are cleated and put enough tension to stop the shrouts from flapping loosely. This is important to hold the mast in place for raising the main and for sailing!
    Once you are out sailing upwind or on a reach, you can recheck if the leeward-shroud is still flapping and then tighten the rig tension. But be aware that the windward shrout bears all the tension from the mast and the power of the sails, so it is natural that the leeward shrout is rather loose and this should be left that way! Just make sure, it is not flapping.
  2. (Albacore only) If you know what a mast-ram and prebend are, check that they are loose! Racers sometimes forget to undo them and that's not good for the boat.
  3. Albacore: Set the outhaul with a little tension on it, cleat it, and forget about it.
    Laser: Set the outhaul so that the largest draft at the boom is about one hand deep (i.e. your hand between the boom and sail). Cleat it and forget about it.
  4. On the Albacore many people don't even attach the cunningham. On the Laser you always want to attach it, so that the pulley system stays in place and does not fall off. But you don't put any tension on it. (Well, you could, but too much tension is definitely worse than none at all.)
  5. Make sure the boom vang is cleated on both sides, but don't put any tension on it. Having tension on the vang can be a problem when letting out the sail for reaches and runs and can also lead to capsizes, so don't use it unless you need to and make sure you release it when you go to a lower point of sail (reach or run).
As you can see this is very easy and pleasure sailing in medium wind does not need any adjustments for point-of-sail, other than than sheeting your sails.
Another trick worth mentioning: raise your centerboard halfway when approaching the dock. This makes it safer in case you sail towards too shallow waters, and it also allows any weeds to run of the board instead of getting stuck in the boardcase when you raise it at standstill.

Pleasure sailing in winds above ten knots (Laser and Albacore):
  1. First of all, with more wind, boat handling becomes more important: hike well, let the sail out, steer, all independently without one messing the other up! A Bronze class is a good way to train this, as is going out with an Old Salt in higher winds.
  2. Second of all, you want some boom-vang upwind and on reaches as explained above. Make sure that the top batten is more-or-less parallel to the boom. As long as the wind is really high, it is okay to leave some vang on even on a run. You don't need to adjust it all the time. Rather play your sheets!
  3. Third, if you are going upwind and have to let a lot of sheet out, even if hiking fully, it is time to depower the boat. Here's what I do:
  • First of all, check that the rig tension is set as explained above, since you need more in higher winds. This is important to keep the boat together and resist the wind. (Yes, it also changes the shape of the mast, but that's another story and it's why you don't put on too much.)
  • I assume that you already have some vang on to remove twist in your sail. Now you can put on more and look at which effect it has on your sail: the top half of the sail should become flatter and the mast bend slightly backwards. Removing draft in the top of the sail removes heeling moment and makes hiking easier. But don't overdo it: even with so much vang on, you still can't sheet your sail in all the way (and you don't need to in order to move forward and stay on course).
  • When it gets more windy, you can also put some cunningham on to remove the wrinkles that you probably have at the luff of the sail (but don't put more, since it changes the shape of the sail).
  • Also, you can tighten the outhaul which makes the bottom part of the sail flatter. But remember that the bottom part of the sail is more important in high winds, since it has less leverage to pull the boat over! As long as the wind is not too strong, don't put too much outhaul on. (Note: outhaul is much more effect on the Laser than on the Albacore!)
  • As long as you don't overdo the depowering by flattening the sail, it might even make you go a little faster, since it reduces drag. Remember that you are sailing as close against the wind as you can get and it is obviously better to present the wind with less surface on which to push you backwards.
Vang versus sheet upwind (Laser and Albacore):
  • Especially on a Laser you will notice that pulling your sheet in tight will also bring your boom down by a lot. If you don't have any vang set, you will see that the vang gets a lot of loose in it by pulling the sheet tight. In the Albacore this effect is less pronounced in medium to high winds with no vang on. Especially on a Laser you will notice how the shape of you sail changes just by trimming the sheet between close hauled and very tight (where the pulley on the boom almost touches the pulley on the transom). You can see that this bends your mast and flattens the upper half of the sail. But now, when you want to let the sheet out in a puff, this will first let the boom go up and then out, which is not quite what you want to depower. Therefore, as one rule to set your vang on the Laser: pull the sheet all the way in and then pull the vang just to take all the loose out. As a result, the vang will hold the boom down and you can use the sheet purely to let the sail out and pull it back in. As a nice side-effect, the boom-vang will prevent the transom-pully from lifting up from the hull.
Personally, I think that one would be quite good in racing trimming just those things and not more, as long as boat-handling, tactics (esp. the start) and strategy is right. Unfortunately, however, I am also am those tempted to tinker with all those controls all the time.


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