There are many different ways to trim the sails on a yacht. The most basic lines used to set and trim sails are the halyard and sheets on a headsail and the halyard and mainsheet on the mainsail.
In addition to this, we adjust the sheeting angle of the headsail by adjusting the car position. With the mainsail, we adjust the angle of attack and shape of the sail by using the mainsheet and something called ‘the traveller’.
Most yachts have a traveller. It is a track which runs horizontally across the cockpit or coachroof and to it is attached the mainsheet mechanism, which is itself connecting the traveller to the boom. Most absolute novices will not touch the traveller at first. But this doesn’t mean it isn’t an essential part of the sailor’s trimming toolkit.
If we didn’t have a traveller, the only way to adjust the angle of attack of the luff of our mainsail would be to adjust the mainsheet. But our mainsheet also affects twist of the mainsail by opening and closing the leach.
Therefore, once we have set our preferred mainsail shape, we can still adjust the angle of attack by leaving the mainsheet, cunningham and halyard tensions alone and instead just ease or tension the traveller by easing it down the traveller (to the leeward side) and decreasing the angle of attack or by bringing it up the traveller and increasing the angle of attack. Assuming, of course, that our heading and the vessel’s angle to the wind, remains the same.
In very simple terms, when sailing close hauled, it is usual to have the boom centred on the yacht and then trim the sail with reference to the telltales and by using the mainsheet. Of course, halyard and cunningham tension and outhaul tension also play vital roles in sail shape.
As the apparent wind increases, the yacht might become over-powered. At this point, especially on a performance yacht, adjusting the traveller and the backstay will influence the angle of attack of the mainsail and the rig tension and sail shape. For more information on the role of the backstay click here.
As we reduce the angle of attack, we spill wind and depower the mainsail. Eventually, once the mainsail is at the leeward extent of the traveller and the sail is sheeted in hard and flat, it may be time to consider taking in a reef.
As you bear away onto a beam reach or broad reach, it is usual to ease the traveller down the track when adjusting the mainsail, halyard, cunningham, outhaul and, perhaps, the backstay.