TEST 1: THE PREVENTER
We set off into Plymouth Sound with a light westerly breeze. It was ideal test conditions: strong enough to fill the sail but light enough that we could experiment safely. A preventer should always be connected on a safe point of sail, with an experienced person at the helm. If possible, don’t ease the mainsheet too much before connecting it, so that if there is a crash gybe at this point it won’t have so much travel. If you’re short-handed, it’s better to ask the novice crew to do the deck work whilst you remain on the helm: taking the preventer off the guardwires and reaching up to the boom to connect it to the pennant is easy if it’s already rigged. Alternatively you could heave-to, which will bring the preventer to the high side, and then gybe out of the heave-to and ease the mainsheet once set on a broad reach. All of these options depend on the conditions, and your sail plan – the more mainsail there is up, the more difficult it is to come up to wind.
On most boats the mainsheet needs to be welleased for the preventer to clear the forward stanchion posts. Once attached, the preventer needs to be well-tensioned to reduce any dynamic loading in the event of a crash gybe.
We gybed the boat with the preventer on. The mainsheet came slightly slack – there was some stretch in the preventer system, but the boom held. It felt precarious and it wouldn’t have been comfortable to stay that way for any length of time, but it gives an opportunity to either ease the preventer and sheet in the main (but beware, this may risk bending stanchions as the angle to the boom changes), or gybe back again onto the original course.