When sailing, it is sometimes found that the mainsail trimmer and helmsman disagree on how to regulate the power of the mainsail. What should we use, the trolley or écoute?? Actually, both answers are correct. Here's how these settings work and how to use them.
The trolley directly controls the angle of the boom to the wind. The mainsail acts first on the twist of the sail and then on the angle of the boom to the wind. Indirectly, these adjustments steer the boat, as the heel changes the course of the sailboat when passing through reefs and slack water.
Mainsail trimming procedure
First, in light winds, you start by adjusting the mainsail twist with the sheet. Then, using the trolley, the boom is positioned in the centre of the boat in order to generate maximum power and to be able to steer as far as possible, as long as the rudder pressure and heel are satisfactory.
As the wind gets stronger and the sheet is tucked in to tighten the leech, the traveller will gradually be lowered, keeping the boom more or less in the centre of the boat.
In the medium wind
The role of the trolley will extend to bar control. If the boat becomes fiery and the heel is too pronounced, the boat will lose handling and performance. In order to regain steering balance, the trolley must be let down so that the power can escape.
In these conditions, in order to maintain good control and good steering feel, you must act on the trolley with amplitude and speed. When a ripple arrives, you have to shock the trolley hard, the extra pressure will turn into acceleration rather than heeling. Be careful, however, if the trolley is not raised in time, you will miss the opportunity to steer after accelerating.
The trolley should be regarded as a fine adjustment of the power. As long as the wind variations are not too great, the trolley will keep the boat in line. The magic of the trolley is that the mainsail twist (controlled by the sheet) is retained, allowing the boat to keep speed and course, you only adjust the amount of power.
However, in gusty and oscillating wind conditions, the mainsheet may be the most effective way to control power and stability.
Mainsail sheeting is the raw power adjustment
If the wind still increases and shocking the traveller is not enough to maintain a proper heel, it is time to use the big means and switch to mainsheeting. Twisting the sail will release the extra power.
This will require tensioning the boom vang, which will be responsible for maintaining the boom height and twist of the mainsail when the sheet is shocked. Thus, with the sheet, the sail is allowed to luff up in gusts and in soft conditions the sail is tucked in (moderately) to inflate the sail. Usually the traveller is in an intermediate position so that the bottom of the mainsail is still working.
Each boat is unique
But obviously each boat is different, which will sometimes lead to other choices being made. For example, on fractional rigged boats with a large mainsail, the sheet is used more systematically and the traveller is usually close to the centre. The large sail area makes the boat's speed particularly sensitive to small changes in sheet tension. The key to performance lies in the quality of the mainsail twist, and therefore the sheeting.
Of course, the professional trimmers are constantly adjusting the mainsail with the traveller and sheet according to the overall power, but also to the boat speed, waves and of course tactical choices. If the boat is below its target speed, it will probably be necessary to act on the traveller and sheet. If there is a wave train, you will have to heel a little and accelerate. If you are a bit above the layline, it will pay off to loosen the sheet and the traveller slightly to switch from heading mode to speed mode.
