We must trim “change” the sails to reflect the boat’s angle to the wind (point of sail) and cater for changes in apparent wind velocity to control the “power”.
If the sails are not trimmed correctly they may “luff” or fail to work effectively.
If a boat is overpowered when upwind and reaching you may experience excessive heel and weather helm (having to fight the helm to keep the boat from rounding up into the wind). In light to moderate wind, you will want to trim effectively to make the most of what wind there is. 
Upwind (also referred to as “close-hauled”, “beating” and “on-the-wind”)
- Trying to sail as close to the wind as possible with-out sails flapping.
- Mainsail and headsail should be trimmed in tight (guideline boom does not go over centre line, headsail just kissing side stay)
Reaching (Close reach, beam reach and broad reach)
- Sailing across the wind
- Mainsail will be approximately half-way out, as will headsail
Downwind (also referred to as running)
- Sailing away from the wind
- Mainsail and headsail will be eased nearly all the way out
Tell Tales (woollies)
Tell tales are the strips of ribbon or wool on either side of the sail which we use as an aide to ensure the sail is trimmed correctly.
| Ideal trim | Sail too far out or sailing too close to the wind | Sail in too tight or need to point closer to the wind | |
| Both tell tales flowing back in parallel | Inside or windward tell tale not flowing, outside tell tail flowing back | Outside or leeward tell tale not flowing, inside tell tail flowing back | |
| Equal wind flow over both sides of the sail | No wind flowing over the windward side | No wind flowing over the leeward side | |
| Upwind (sails already in tight) | Keep sailing fast | Too close to the wind: Come down – pull the tiller toward you | Not sailing close enough to the wind – push the tiller away |
| Reaching | Keep sailing fast | Trim sail in | Ease sail out |
TIP: If in doubt – let it out. Then pull it in until the tell tales are flying nicely
