Everything you need to know about trimming and trimming tools
The practical handling of the sail is made possible by trimming the rig in a modified manner, such as the modification of boltrope tension and the position of the clews of the sails. The prerequisites for the effective trimming of a sail in fluctuating wind conditions are correctly adjusting the tilt of the mast astern - the so-called mast rake - and the tension on the wires. Proper tension of the shrouds and stays occurs when the halyard on the mast stands straight in the wind. Of course, it’s desired that the lee shrouds lose a certain amount of tension, considering the greater amount of pressure on the rigging in this case. Please make sure that the lee shrouds don’t tremble!
1. Trimming the headsail on a backstay
In light winds, the foresail works best when it has a low profile with an almost closed leech. Thus, early pressure can build up easily, even during a slight breeze. When the wind picks up, the sail profile becomes flatter. This gives the sail more twist in its upper section. The desired effect occurs: The energy of wind is converted in to the active propulsion of the yacht, the ship moves upright, which creates lower pressure at the helm. The trim on the headsail is mainly carried out by the luff. The luff is initially controlled by a drop in tension and affects the position of the sail’s profile depth.
A similar effect occurs in the case of a loose forestay, when the leech closes to a greater degree, creating a greater profile depth. Both of these situations allow for more pressure on the sail, which increase the hell and decrease the speed. This is desirable in light wind, in order to generate a lot of pressure on the sail - but if the wind picks up, the forestay tension should be increased to maintain the position of the profile depth and to produce a flat sail profile. How can I control this sagging effect in high winds? Simply by trimming the standing backstay with a backstay tensioner. The geometry of the rigging is controlled by the tension of the backstay on the forestay and thus the forestay tension regulates the profile depth of the headsail.
2. Trimming the mainsail
Over the past few years, the mainsail has become increasingly larger, making it more efficient in propelling the sailing yacht. When trimming the mainsail, one must focus on 3 essential characteristics:
- The luff angle
- The setting angle
- Leech twist
Trimming by regulating the luff
The profile of the mainsail is much like the headsail, heavily influenced by the luff and the luff angle. In increasing wind, a higher amount of tension on the luff must be exercised, in order to produce the greatest profile depth on the sail and to prevent it from wandering astern. In the case of the mainsail’s luff tension, this is initially applied by the main halyard - adjusted by means of a halyard winch - as the rope to set to the mainsail. In increasing wind speeds, it’s suitable to regulate the luff tension with a so-called Cunningham jig. Through an additional reefing clew, an outhaul is led and securely attached to one side of the foot of the mast. The other part of the rigging leads to either a windlass or is attached to a clamp at the mast base. If the sheet is pulled tight, the luff on the mainsail moves downwards, increasing tension. This has the same effect as having a stronger halyard on the mainsail.
Regulating the setting angle
Both the traveller, as well as the boom vang are used to prevent uncontrolled rise on the boom. Without this trimming, the leech would open too far as soon as the sheet was eased, leading to too much twist on the sail. The setting angle is the angle between the direction of the wind and the tread chord width. To trim, the setting angle of the mainsheet is absolutely necessary: The tighter the mainsheet is brought in, the smaller the setting angle will be.
Regulating the setting angle with a traveller
What is a traveller? The traveller is a trolley that is mounted on to a traveller track, which is the point of attachment for the mainsail’s sheet. This point of attachment dictates if the sheet is either shifted luff or lee. So that the skipper can adjust the setting angle and thus trim the mainsail. If one allows the traveller to continue to run lee without slacking the sheet, the angle becomes larger, but the twist remains unchanged. The optimal traveller has a length, which spans over the entire cockpit width and it should run smoothly and be fully adjustable, even under heavy loads.
Regulation of twist - the boom vang
When the mainsail is eased along the length of the traveller, the boom vang controls the height of the end of the boom and leech and therefore the adjustment of twist. The twist is the torsion of the sail’s profile, from bottom to top and it’s controlled by the boom vang in combination with the traveller track. The sheet on the mainsail then regulates the angle of the mainsail.