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How to Reef the Mainsail


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Why and How to Reef the Mainsail
Mainsail Reefing

Photo © Tom Lochhaas

Reefing the mainsail involves lowering the sail partway to reduce its size when the wind increases. A reefed sail reduces heeling of the boat and makes the boat easier to manage. It also reduces the risk of capsizing in a gust. Reefing the mainsail is like partly furling the jib when your boat has a furling jib.

When to Reef

The classic sailor’s saying is that if you are asking whether it’s time to reef the main, it’s already past that time. This refers to sailors who are having difficulty controlling a wildly heeling boat because the wind has gotten up and is putting a lot of pressure on too much sail area.

A prudent sailor reefs the main when the wind starts to build, before things get wild. When the wind is blowing more than 12-15 knots (depending on the boat), conservative sailors will start out with a reefed sail. Over 20 knots on many boats, it can become difficult to control the boat for smooth reefing, especially when short-handed.

Remember that when you’re sailing downwind and the boat is not heeling, you may not notice at first that the wind is increasing. Pay attention! Since you have to turn up into the wind to do the reefing, things may get dicey if you wait too long to reef.

How to Reef

With the common slab reefing system, reefing is fairly simple, though it’s a skill that requires some practice. The basic steps are:

  1. Turn the boat toward the wind and ease the mainsheet to reduce pressure on the sail.
  2. While slowly easing the main halyard, take in the reefing control line. This pulls the bottom of the mainsail down toward the boom.
  3. When the sail reaches the desired reef point, secure the halyard and the reefing line, go back on course, and trim the sail.

Go on to the next page for a diagram of a slab reefing system and how to make and use one.

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  5. Traditional Slab Reefing for the Mainsail

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