Reefing or reducing a conventional/non-furling mainsail can be done by way of either a slab or a single line reef system. Today I want to talk about the difference between the two reef systems and how they should be set up.
FIRST: Read below for a few thoughts on reefing procedure
When reefing, conditions are usually rough and frustrating. Take time to first make sure that you are safe and tethered to the boat (in position to perform the reef). Try and stay calm and think clearly about what you are doing, and what you are about to be doing. Ensure all leads are fair, ensure the boom topping lift has been snugged-up (this is very important), release the vang and then the main sheet slightly so as to just luff the sail. Now release the main halyard. Be sure to pay out enough halyard so that the reef is actually below the boom. If the wind is so strong that the sail won’t lower easily, make sure the halyard is still free to run and pull the reef line and/or jack lines at the luff slides to help lower both ends of the sail. Now, continue to tension the reef line (you should be able to do this without a winch) and tuck the inboard and outboard ends to the boom. Once the reef is tucked, double check to make sure all leads are fair and take the reef line to the winch and begin to tension it adequately. Lastly, tension the main halyard, loosen the boom lift and then sheet-on as needed. When the boat is stable again and everyone is settled in, safely, go and clean up the reef slabs.
TIP: friction can easily be overcome by your winches, but be careful, because this is how things get broken!
Since more and more boats these days are leading the halyards aft, single line reefing has become a very popular method for reefing your mainsail. Single line reefing essentially means that the outboard and inboard reef cringles use one line to tuck (or haul down) both ends of the sail. In general, this system is configured in two ways:
One is to ‘simply’ run a line from the outboard dead-end, up through the o.b. reef cringle, down to a sheave at the o.b. end of the boom, which will turn the line forward to another sheave at the inboard end of the boom, which will turn the line upwards to the i.b. reef cringle, then down through a fairlead on the mast to the deck and aft via a series of (you guessed it) more sheaves, then to a clutch, and finally to the winch (gasp!).
The other method’s end result is the same (one line to pull on, back in the cockpit), but it adds yet even more sheaves. It does this utilizing ‘shuttle blocks’ which run on the inside of the boom. The shuttle block system, although providing more purchase, can cause increased friction and even worse – lines to become twisted or tangled inside of the boom; this can make it difficult or even impossible to reef the mainsail when necessary. Reef systems that utilize shuttle blocks can also be problematic in that they can limit the height of the reef point to the length of the boom. ~Pay attention to this if having a new sail made~
In order to make things simple we, at The Rigging Company, prefer the first system – no shuttle blocks. Although this method does not offer any additional purchase, your cabin top winches will surely be able to overcome any load that you might encounter.
For more information on leading lines aft, read here.
Additionally, it may be advisable to hang small high load blocks from the sails cringles to reduce the friction further. Also if you are noticing that the inboard end is tucking sooner than the outboard end, hanging a block from the OB end only may balance the system out a bit more.
NOTE: For either of these systems to work efficiently the boom needs to have sheaves oriented in such a fashion that the line can both enter and exit the TOP of the boom. .
Traditional slab reefing is a much more simple and classic approach. Slab reefing is intended for use on boats where the halyards are left at the mast. This system also uses just one line per reef; but this line is only responsible for the out-board/clew-end reef. Typically the in-board/tack-end is then reefed separately either
via Reefing Hook (see picture) or Cunningham. A good slab reef system should lead to a dedicated winch located either on the inboard-side of the boom, or just below the boom gooseneck on the aft face of the mast (see below). If the boat is equipped with multiple reefs, all lines should be cleated using rope clutches before the winch (anytime more than one line leads to a winch the use of rope clutches is recommended). Leaving everything at the mast, properly rigged, will ensure the least amount of friction out of any reefing system.
There are many variations and details in setting up one of these systems on your boat. Please consult with your local rigging professional to determine which set up is the best for you.
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