De-powering a Sail Boat
The question arises many times; how do we keep the boat flat when it gets windy?
First, we need to discuss how to move the center of effort on the sails down to a manageable area and how to flatten the sail.
The obvious answer to both is by bending the mast, the next answer is by opening the leech (which are interlinked).
In this video we see the 470 sailing team having a very open leech on a very flat main sail, this set up is reducing power at the top part of the sail, hence moving the center of effort down so the sailors can manage to keep the boat flat and fast.
In a 470 we also have the ability to play with the leeward side traveler, that in turn will allow the boom to lift up slightly more while remaining at the middle of the boat, hence keeping the bottom part of the sail with good flow while further opening the leech. Incase that is not enough, the helm will need to release the main-sheet to further depower the sail (as he does on the video).
During our sail coaching sessions with the East Java team we spend enough time in teaching the sailors the different interactions between the controls of the boat and allowed them plenty of time to experiment and feel how it effects their boat, the end result was a huge improvement in boat speed for the entire team and 7 medals at the PON Games 2016.