sailing - page 9

2.9 Reefing 

Reefing of sails should occur at or around 16 knots of wind. Reefing is simply the art of reducing the amount of sail area. It reduces the heeling over force from the wind and helps the wind stay attached to the leeward side of the sail thus reducing turbulent inefficient flow of wind.

Reefing the headsail

The majority of fin-keel cruiser/racers these days are equipped with roller-furling genoas. The mechanism is low-tech, simple, and dependable. The genoa is hoisted in a luff groove on an aluminum extrusion around the headsail. The extrusion is conected to a drum (photo 2.9.1) at the foot of headstay. A sinlge control line is wrapped around the drum and led aft the cockpit. Hauling on the control line causes the drum and the extrusion to rotate, thus wrapping the genoa around the headstay. To re-set a roller-furled sail, all you need to do is uncleat the control line and haul on the sheet. To reef it, ease the sheet and haul on the control line. The sail obedientrly rolls around the headstay. 

headsail drum.jpg
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photo 2.9.1

Headsail drum

A sailboat with  in the headsail

Reefing the mainsail

The mainsail reefing can be done in two ways depending on its type. One is, roller-furling around a suitable mechanism inside the mast, a part of the sail depending on the prevailing conditions. This system is used by several cruise ships. The other way is, the mainsail must be hoisted up (slab reefing) with the main halyard to begin sailing. When reefing, the mainsail must be lowered to reduce its sail area by using the reef 1, reef 2 or reef 3 according to the wind speed. 

  • Roller-furling mainsail

The process of unroll the furling mainsail is simple as it requires the handling of only two lines which are located on the cockpit clutches. Pulling the outhaul (rear system) and loosening at the same time the rope of the roller mechanism (photo 2.9.2) the sail is getting out from the mast. The sail can get out 100% or as much as we desire according to the wind speed. The opposite procedure should be done in case you want to roll a furling mainsail inside the mast. 

roller.jpg

photo 2.9.2

Roller mechansim

  • Slab or Jiffy reefing

The modern system for reefing the main is called slab reefing. The objective is to shorten the main by lowering it. Notice (1) the metal hooks mounted near the gooseneck and (2) the heavily reinforced ring called a cringle (photo 2.9.3) about three feet up the main luff. To reef, you ease the halyard until you can slip the cringle over the hook. You have then shortened the main luff. Retighten the halyard. That is step one.​

Now you need to shorten the leech an equal lenght. the sailmaker has accommodated this by placing another cringle in the leech at the same height above the foot as that in the luff. A rope, the reefing line, tied at one end to the boom runs up through the cringle, back down to a block on the other side of the bomm, thence forward inside the boom to an exit and a cleat. Hauling on the leech line pulls the leech cringle down to the boom. Cleat down the line, and you have reefed the main. 

The explanation of the system may be more complicated than the system itslef. With practice, one person can reef the main faster than the time it takes to read about it. 

When reefing you will do one sail at a time. You can reef the boat while still under sail with the other sail still propelling the boat. You can won't be able to lower the halyard when the mainsail is full of wind. Spill the wind from the main before you try to reef it. If the wind is forward of the beam, you might be able just to ease away on the sheet until the sail flogs. That of course won't work if the wind is aft of the beam, in which case you'll need to turn the boat up into or near the wind before you reef. 

To "shake out" the reef, ease the halyard enough to detach the tack hook. Release the leech line from its cleat, and then tighten the halyard to full hoist. 

Most boats have three reef points, called first reef, second reef, third reef (photo 2.9.4). This means that there must be three sets of cringles, one atop the other, in the luff and the leech. 

The lazy bag is a modern type of a sail cover. It is secured to the boom and zips closed at the top to protect the sail from sun damage when it's not in use (photo 2.9.5). 

photo 2.9.3

Hook and cringle

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photo 2.9.4

Reef points

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photo 2.9.5

Lazy bag