Conventional Mainsail Reefing

Reefing the mainsail

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

Heavy wind big storm sailing

  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!

Single line reefing

Single Line Reefing

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.

Single lien reefing, shuttle blocks

Single Line Reefing with Shuttle Blocks

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. .

Tack-end Reef Hook

Tack-end Reef Hook

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.

Slab Reefing

Slab Reefing

Peterson 44 Boom, 2 Internal/External Reefs

A Properly Configured Multiple Slab Reef 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.

Reefing Winch

Reefing Winch Below the Boom

Leave us a question in the comments below. We will reply!

About The Rigging Company, LLP

We provide complete and professional rigging products and services!
This entry was posted in Classic Yachts, Cruisers, Racers, Rigging, Tech Tips and tagged , , , , , , , , , , . Bookmark the permalink.

19 Responses to Conventional Mainsail Reefing

  1. Tor Melin, Sweden says:

    Hi there in the U.S.!

    I have a plan to make a single line reefing system on my 43 year old Hallberg Rassy Monsun 31 berthed on the south coast of Sweden. She is now equipped with a well working slab reef. The idea is to draw the lines down to the cockpit by some drilling and fixing. I have discussed with people and they say that friction is the main problem to overcome. After extensive thinking and paper drawing, but still not testing, I have come to the following solution: The line starts with a knot in the outboard cringle in the sail. Down to a sheave near the rear boomend. Ahead to a sheave on the boom front. Up to a block in the sail inboard cringle. Down to a block on deck and then aft. That would make a sum of 4 blocks/sheaves and no passages through rings. The drawback would be that everything will be on one side of the boom. I dont know if that will make the sail inefficient in any way? My thoughts is that this construction would minimize friction. What are Your comments on this idea?

    • The Rigging Company, LLP says:

      Hi Tor,

      That’s exactly how it’s done. Just don’t forget to add the fairlead at the mast, below the gooseneck. See the drawing for single line reefing in the article. Thanks for the read and let us know if you need more thoughts.

      ~T.R.C.

  2. Priscilla says:

    @ Howard: You didn’t REQUEST a third reefing point??! You probably don’t need it then so just ignore it. I have three reasons for a third reef, and it took months to figure out how to rig it for its intended uses. Assuming we are talking Bermudian/marconi rigs, the third reef is not in the same location as the usual “top reef” – you would (logically) only have a third reef for a high-aspect mainsail, the location reduces sail area to about that of a trysail.

    That third reef point is a lo-o-o-o-ong way up there, and even though my boom has room for a third line (the old main had a flattening reef) I didn’t want a reefing line going up there for a reef I will seldom use. One of my reasons for the third reef was to have an option for an emergency/temporary trysail, so my whole system had to be designed for that use (severe storm conditions and there is a problem if my trysail isn’t deployed instead), plus my personal needs (blue water singlehanding requires a fast and easy way to rig the reef clew ring in rough seas so I can quickly get away from the boom and off the cabintop, and simple enough it can be accomplished at night while I am tired or possibly injured). I did extensive research for how to hook up the reef clew ring on that third reef and didn’t find anything useful, so I designed a system that fulfills all my requirements. If there is any interest I might write an article about it for Ocean Navigator later this year.

  3. Howard Rudd says:

    I have had a new mainsail made and the sail makers provided 3 reef points as opposed to the two specified, I have only two reefing lines. I questioned whether the spacing between the reefing points should be different for a two reef system as opposed to the three point system. they tell me that the distance between the reefing points would be the same, they would simply not provide the top most reefing point. Is this correct ?

    • The Rigging Company, LLP says:

      Hi Howard,
      This questions is typically better suited for <a href=”http://www.chesapeake-sailmakers.com/”>a sailmaker</a>. Here are my two cents..I believe that the top reef is always at about the same location. The fabric weight can only handle so much and reducing sail beyond that would require a different (heavier) sail. The amount of reefs you have just break down the area below that top reef. Much like a transmission in a car, if you have a four speed you can still go 85 VS a 6 six speed, there are just more shift points before you get to 85. Does that make sense at all?

      I wouldn’t fret about not having that third reef line You can rig the two points in the sail that suit your most likely conditions. If you are on the Chesapeake you’d likely leave that third reef alone. What you can do is rig a small diameter loop between reef 2 and 3 so that if you need access to that last reef you can take the reef line that is slack and feed it up through the top reef via the messenger loop.

      Hope that helps!

      ~T.R.C.

      • Howard Rudd says:

        Thanks for that, I follow your reasoning and it makes sense. However I doubt I’ll ever sail in Chesapeake bay, the Solent in the UK is my main cruising area!!
        Fair winds and happy sailing.

        Howard

        • The Rigging Company, LLP says:

          Sweet! You’d better rig reefs 2 and 3 then ;). I love that we have readers in the UK.

          ~T.R.C.

  4. Bradford A Milller says:

    I would like to get another shuttle block for my Freedom 35 and see if it works for me. Can you supply me with one?

    • The Rigging Company, LLP says:

      Hi Brad,

      Absolutely. 1st try going straight to the source.

      Sometimes they can be a bit difficult to deal with. If you have troubles please call our Bradford in the office and he will see to it that you get the exact part that you need.

      Regards,
      TRC

  5. Marie pousset says:

    Hello I have a reefing system with a kind of blockers in the boom and I can’t find how it’s worked??
    This system block in the 2 way!!
    I have some pictures to show you!!
    Needs help please!!
    Marie

  6. Ruth says:

    you say “hanging a block from the crinkle”, how? using a snap shackle, or sewing a block on so that it ‘hangs’ down , but then the line would all be on one side. confused !

    • The Rigging Company, LLP says:

      Hi Ruth! Yes, you can hang a block or a friction ring (Google Antal friction ring with loop). There are a few methods to achieve this and yes, it would result in the line going up and back down the same side of the sail as it won’t pass through the sail anymore.

      One is to use a Dyneema loop with a ring hitched to it on one end (the ring keeps it captivated in the cringle) and hang the block or friction ring from it.

      Another is to have sailmaker sew a webbing loop to the sail and hang a block. Lastly, you can have the sailmaker sew in webbing with two rings, that is rigged through the cringle (much like the Dyneema loop and ring mentioned above) and hang the block from it…. called a “Dog Bone”.

      Hope that helps and thanks for the comment.

      ~T.R.C.

  7. Anonymous says:

    Can you please explain the correct way to secure the cringle to the Tack End Reef Hook without punching a hole in the sail? thanks.

    • The Rigging Company, LLP says:

      LOL well, it is slightly funny that you say that. I just went on a sea trial last week with a customer to use their new single line reef system, which omitted the old reef hooks. And guess what happened…one of the flakes of the sail, while reefed, caught on the stupid reef hook, which aren’t even needed any longer and poked a hole right in the sail.

      So, there’s my story, but if actually using the reef hook correctly it should not be doing that. Simply lower the halyard, hook the cringle onto the sail and re-hoist the main. You’ll need to hold the cringle in place until the tension of the halyard does this for you. Using reef horns at the tack are only recommended if the main halyard winch and cleat are also on the mast so that you can manage both of them at once.

      If this is not the case and the halyard is led aft, then it will be a two man operation, OR re-rig the reef lines as single line reefs, OR re-rig the main halyard so that it is at the mast.

      Hope that helps.

      Thanks,
      ~T.R.C.

  8. Anonymous says:

    Did I miss read the articles? Where does it say release the vang or kicker? The procedure I’ve encountered most would be. After making ready all lines and winches required.

    1 Release kicking strap or vang.
    2 Ease sheet.
    3 Ease halyard
    4 Secure new tack if not on single line system
    5 Take up on reef line. Also hand pull tight all other reefing lines.
    6 Retension halyard.
    7 Trim vang and sheet.
    8 Check over all blocks and wear points, use sail ties to secure reefed sail to boom.

    Coil all lines etc.

Leave a Comment or Ask a Question, We Will Reply!

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out / Change )

Twitter picture

You are commenting using your Twitter account. Log Out / Change )

Facebook photo

You are commenting using your Facebook account. Log Out / Change )

Google+ photo

You are commenting using your Google+ account. Log Out / Change )

Connecting to %s