Seamanship: How to Use a Preventer

Following up on Bob Pingel’s excellent article on designing a serious main boom preventer, this article will examine a variety of strategies on when and how to use the preventer at sea. I will touch on ‘off the wind reefing’, but stay tuned because my next my seamanship article will focus exclusively on off the wind reefing techniques, definitely my preferred way to shorten both the mainsail and headsails and the boom preventer has a big role to play in that story.

Bob is absolutely right, the main boom is the most dangerous part of the boat, and boom control is essential for safe sailing. Boom control is not only vital when sailing off the wind in breezy conditions but also for efficient sailing on all points of sail. The preventer, along with the sheet, traveler and vang are used to corral the boom and make it work for you instead of becoming a deadly battering ram.

Watch the video below closely. You will probably have to replay it a few times. It shows how effective the preventer on Quetzal is as we intentionally jibe the main on a deep reach in 20+ knots true. We are in the Pacific, between Patagonia and Easter Island. The boom doesn’t move, the sail just flops over as it backs. This is a real world demo and how a preventer is supposed to work.