Steering a boat by night is quite a different experience. If there is moonlight or stars then at least you have points of reference to maintain a course by, but when you have neither you have to rely on instruments even when these counter all your instincts. Tonight we are taking 30 minute sessions on the helm as we speed downwind with our yankee (big triangular in front of the mast) poled out on the opposite side of the boat from the mainsail. The range of safe steering is quite narrow which all adds to the tension and requires total concentration, hence the short helming spells of only 30 minutes. The good ship Jamaica knows when your concentration slips for even only half a second and she will mischievously throw in an unanticipated change of direction for fun; or the sea will come at you with a side swipe wave and if you don’t respond immediately the consequences can be dear, but more of that later.
So the technical bit is that the mainsail is fully out at almost 90 degrees to the direction of the boat. It is held in place by sheets (ropes) which add tension from behind and additionally is held forward for safety by a preventer which runs from the end of the boom to the bow and back to the cockpit. This means that if the wind gets on the wrong side of the sail and tries to flip it across to the other side – 180 degrees – the preventer should do what it says and stop it happening. Also known as the dreaded crash gybe.