1 Ponsonby: Turn 45° to port! Trim the mainsail! We need to catch those pirates!
2 Mate: Aye, Captain!
3 {Ponsonby is peering through his scope at the pirate ship}
4 {Mate has returned, holding a piece of cloth}
4 Ponsonby: What’s that?
4 Mate: Is that enough trimmed off the mainsail?

Trimming sails is actually the procedure of adjusting the tension on them by tightening or relaxing sheets (i.e. ropes in nautical terminology), in order to optimise their performance in the prevailing wind conditions. The sails need to be either tauter or slacker to best utilise the wind and minimise drag, depending on the wind speed and its angle to the boat and sailing direction.

Someone should presumably tell the Mate this.