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Skills Refresher

ACADEMY SAILING BLOG

Writer's pictureAndy Barnes

How to Reef a Slab-Reefed Mainsail on a Yacht: A Simple Guide

We've been asked to put a short article online that covers reefing and so Andy Barnes, Academy Sailing's Chief Instructor has put the following simple guide together for us.


Know when to reef your sails

Reefing is an essential skill for any sailor faced with increasing winds. In this short article I will focus on how to reef a `slab reefed mainsail as these are the most common saling yachts in the UK.


So what is `reefing'? Put simply, reefing is the process of reducing the area of a sail on a boat or yacht to decrease the power it generates, improving control and stability in strong wind conditions.


When do you reef? Well as the saying goes, `when you first think about it, reef!'. Don't wait - do it when you first find yourself contemplating it. The opposite is true when it comes to `shaking reefs out' (making the sail bigger again), when the advice is to stick the kettle on, have a cup of tea, and only then if it still seems like a good idea then shake the reef out!


Reefing the mainsail

To be a little more precise, with most yachts, the first reef normally goes in with around 14 or 15 knots of apparent wind. Then 19 to 20 for the second reef, and then 23 to 25 for the third reef. But, keep in mind that each boat is different due to many factors including size of rig, how `deep' each reef is (how much is reduced), and how they sail. Also keep in mind that when heading downwind you can carry a much bigger sail area, but if you do need to reef then you will have to turn round into a sea that has probably built up. That means that if you really leave it late to reef when you are heading downwind, then you may have a rather unpleasant or certainly uncomfortable situation to manage. And if you or your crew are light on experience then this can make things more intimidating. So sail conservatively as you build your experience and sea-miles in stronger conditions.


So if you have a slab-reefed main and a furling head-sail, here is a step-by-step guide to help you safely and effectively reef your sails.

Preparatory Steps Before Reefing


  1. Know the Boat: Make sure you fully understand the set-up on the boat before you go out. Sounds obvious but if you aren't familiar then work out how everything works as there are a number of different ways the boat could be set up to reef.

  2. Weather: Always keep a close eye on the weather forecast as this will give you an early heads-up on the liklihood that wind speeds are picking up. Keep in mind that wind speeds increase as you head-out into open water. And that the wind is often stronger than apps like Windy indicate. The Met Office Inshore waters forecast is excellent though.

  3. Safety: Ensure that everyone on board is wearing a life jacket - and life-lines if necessary. Secure all loose items on the deck as well as below deck as when you head onto a a close-haul to start reefing, things can get a bit bumpier. Also choose where you reef to make sure you have plenty of space around you and that you aren't going to come into conflict with another vessel, an obstacle, or the seabed in shallow areas!

  4. Crew Briefing: Make sure your crew understands their roles in the reefing process.

  5. Reef the Head-Sail First: Decide whether you need to reef the head sail. If you need to furl some of it in, decide whether you want to bear away downwind to help depower it whilst you furl, or whether you want to head into wind to slightly luff it whilst doing the same. Downwind may be easier but will depend on how powered up the sail is.

Reefing Process for the Head Sail

  1. Head Up or Bear Away: Depending on what you decided for reefing the headsail. When ready, gently ease the head sail working sheet out as one or two of your crew pull on the furling line (keep jammer / clutch closed) until you have the right amount of sail left out.


Reefing Process for the Main Sail


  1. Positioning: Head up into a close hauled sailing position to allow you to ease the main sail out to de-power it whilst you continue sailing on the head sail alone.

  2. Ease Mail Sheet: This will depower the main sail. Also ease the kicker and at this point also tension the topping lift if it is loose.

  3. Ease the Main Halyard: Load main halyard on the winch, take up tension before opening the clutch ready to start easing to lower the mainsail. You only need to lower it until you reach the required reefing point.

  4. Secure the New Tack: Depending on the set-up this may mean pulling in on a reefing line in the cockpit to make sure the new tack of the main sail. What you are doing in simple terms is taking a point somewhere originally higher up on the luff, and making this the new `bottom bit' fixed to the where boom meets the mast. Sometimes instead of a reefing line, this may mean going to the mast to hook one metal ring (often 'spectacles' hanging off webbing passing through a 'cringle') onto a hook (the `ramshorn').

  5. Re-hoist the Main Sail: Re-tension the main halyard until the luff is fully tight with the new tack being set.

  6. Secure the Clew: Next, pull on the reefing line associated with the clew cringle (at the trailing edge of the sail). This line usually runs through the boom and exits near the cockpit for easy access. Pull it until the clew and boom are quite tight to each other - normally within a few centimetres.

  7. Tighten Redundant Reefing Lines: Remember that when you put any reef in, you need to pull the others so there is no slack dangling around. Just don't overtighten them so as to spoil the shape of the sail.

  8. Topping lift & Kicker: Check the topping lift has slack in it (it probably will by this point as the boom will have lifted to meet the newly set clew) and then add some kicker to ensure the boom doesn't lift as the sail powers up again. Re-check the topping lift is loose but not too loose so it can catch on backstays.

  9. Start Sailing: Bear away to your desired point of sail and adjust the main sheet to suit. Doule-check you are happy with the shape of the sail and the lines. Enjoy your better controlled sailing yacht.


Winching in the head sail to adjust sail trim having reefed it

You can put reefs into the main sail as you first put it up. You do this by pulling reefing lines in as you start raising the main sail, and only raise it as far as the reef you want, setting rhe tack first.


Also, remember that when shaking reefs out, the process is the same as the above, except that you need to open all of the reefing line clutches as well, whilst you then hoist the main sail up to the new position before resetting the tack and clew.


Closing Thoughts


I hope this short guide is helpful to some of you. It's no replacement for proper hands-on tuition but it may help as a useful reminder on how to reef if you are a bit rusty or unsure.


Remember, reefing isn't easy unless you and the crew do it regularly. So practice on nice calm days for fun. It's rewarding when you get it right. And don't be afraid to create your own checklist so you can check things off as you go through the process.


Finally, whilst reefing, please pay close attention to your depth, where you are, other water traffic and obstacles. It's very easy to get distracted so pick your spot with plenty of space where you can.

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