Upwind Sailing

Trimming the mainsail

On this course we need to keep the mainsail (as well as the genoa) trimmed with the sheet “full”.

The sheet traveller is fixed “almost” in the centre of the boat, giving a slight inclination of the boom towards leeward. The vang has to be slightly set, thus tightening the leech and bringing the boom down a little. The outhaul has to be set as much as possible (leg tension) and finally the backstay, which tilts the mainmast backwards, has to be well set. The fact of setting the vang and the backstay means moving the sail centre of the boat further aft and this allows it to be luffed more.

Depending on the intensity of the wind and the waves, it is advisable to adjust the sail's "pocket". This will be done mainly by adjusting the outhaul. With lighter winds or strong waves, it is advisable to give the sail more pocket, to give more power to the boat, then the outhaul will have to be carried looser. On the other hand, if the wind is strong, we will carry the outhaul more tightly, thus trimming the sail with less pocket (or flatter).

During sailing, you should also keep an eye on the luff area. If you notice slight wrinkles at the height of the mast rails, this means that the sail is not sufficiently raised.[1]. We have several options for hoisting it, either by maintaining a close-hauled course but opening the sheet so that the sail loses pressure while someone takes in the halyard, or by taking advantage of a tack to take in the halyard during the manoeuvre. This last option is more appropriate if we are tacking close-hauled in a regatta. On the other hand, if when observing the sail we see that the mainsail has a wrinkle coming from the boom upwards, it means that it is too close-hauled and we will have to release a little bit of the halyard. We must release very little of the halyard, just carefully release the rope from the winch clamp and let it slide a few centimetres, always maintaining tension.

On some boats there may be a thin rope coming out from the end of the leech, called a leech. This should also be tied in when sailing close hauled.

Genoa sail trim

When going close hauled, the sail must be pulled in as much as possible, then the sheet must be tightened until it can hardly be pulled in any further (with the winch). At least the skirt of the sail (leash) must fall within the line of the boat's side, normally inside the handrail. In addition, the sail will be close to touching the spreaders, shrouds and side stays.

The sheet traveller should be more aft than in other directions. To adjust it, we will look at the opening of the leech and the foot. If the leech is very open and the sheet comes out of the head almost parallel to the foot, it means that the traveller is too far back, and on the contrary, if we see the leech closed and the foot more open, we will have to move the traveller more aft. Basically, when the sail is trimmed, the leech and the foot have to “close” at the same time. The fine adjustment of the traveller is done by looking at the three rows of genoa fleeces. If the fleeces at the bottom of the sail are parallel but the ones at the top flap, then the traveller must be moved forward. The traveller is fine when the three rows of fleeces do the same, that is, all three are parallel, or all three rise or fall.

When adjusting the traveller, it may happen that the sheet is obstructed by some shroud or side stay and it may be necessary or convenient to change the clew so that it passes behind, in front of or between some shrouds.

When sailing, we often want to go up to windward by tacking as much as the wind allows. With the sails at full sail, the helmsman has to look at the genoa slacks. If the windward and leeward slacks are sagging, it means that we must tack more. When the slacks are carrying the wind and are parallel, then we are in the correct position. We can even tack a little more, until the windward slacks begin to rise, which is the limit of the close-hauled sail. The slacks tell us that we cannot tack any further, but we must not come in either.[2]

Finally, at even finer trim levels, some genoas have a horizontal line or mark in the middle of the sail, which helps to see at what height of the sail the wind pocket is formed. When fully upwind, the sail pocket curves at about 50%. To increase stability and gain speed, it may be interesting to move the sail, and therefore its pocket, further forward. In this situation the boat can be less upwind, but it can be profitable to gain speed and stability. Moving the genoa further forward is achieved by raising it slightly. This is done by giving a couple of turns to the halyard with the winch until the new curvature is at 30%.

As long as we continue on a close-hauled course and up to the beam, the sails serve as a guide to know whether we should luff or bear away, or trim or lighten sails depending on the course we want to set. As we have just seen, if we are going full close-hauled, the sails remain fully trimmed and we only bear away if the windward sail rises too much and we luff if the windward and downwind sails fall. On the contrary, if we want to go on a certain course, we will leave the tiller (or rudder) fixed and instead we will trim the sails to “satisfy” the sails. If the windward sail rises or the luff is about to flap, we must trim the sail more and if the sails fall we must lighten sails. In general, we should sail with the sails carrying the maximum wind and about to flap.

Tack