How to gybe safely

08 May 2018

To many novice sailors the gybe can sometimes become a bogeyman manoeuvre, avoided by many due to a combination of a deeply instilled fear of the process and a lack of understanding around the procedure. To some extent, this is an understandable bi-product of an overprotective instructor or perhaps and overly cautious approach by less experienced instructors keen to drum into their newbie students the dangers of a ‘crash-gybe’. The aim being to ensure that they will continue their sailing career with an appropriate level of respect for the process and the potential for damage / injury if the gybe happens in an uncontrolled manner. 

Unfortunately, this approach can sometimes fall short of the desired outcome with an irrational fear of the process inevitably communicated to the student or, worse still, a lack of understanding of the entire process.

Most of us have probably sailed with someone at some point in their sailing life and come away at the end of the weekend amazed that they have got away without a scratch. Too many boat owners still have a poor understanding for the dangers of an uncontrolled gybe and some even lack basic wind awareness. The latter is a must if you are to sail safely, especially if you are skipper! Of course, learning how to sail requires time on the water, but here are just a few pointers to keep you on track;

What is a Gybe?

Before we address ‘the gybe’, we should perhaps first describe its counterpart, ‘the tack’. If this is well below your level of understanding, feel free to skip down the article.

Everyone, even the non-sailor, could have a good go at describing a tack. Fundamentally, it’s where the front of the boat (OK, the bow) is pointed up towards the wind until it is pointing directly into the wind. As the bow points up to wind and then passes through the wind the boat ‘tacks’ with wind that was once felt to be blowing onto one side of the boat now being felt to be blowing from the other side of the boat. 

Unless you undertake this process whilst a spinnaker is flying (in which case the error of your ways probably needs to be the subject of another, more lengthy, article) then all you will expect to see is the headsail and mainsail will become de-powered, flap a little, ‘back’ and then (assuming the sheets are properly handled) they will fill with wind from the opposite side of the boat. Whilst this process may be a little noisy in windy conditions, the whole process is fairly innocuous as there is little force in the sails as they tack through the centre line of the boat. They may collect the unobservant or poorly located sunbather, but everything happens relatively slowly and the process is quite predictable. This makes tacking a relatively relaxing affair.

The gybe, on the other hand, involves pushing the back (or stern) of the boat through the wind, effectively the opposite of the tack. However, unlike the tack where sails flap and gently fill on the opposite side, when a sailboat gybes the sails (and sheets attached to them) cross the boat in a much more violent manner. If you think about this it is obvious why this is. 

When tacking, you are usually going from being close hauled on one tack, through the wind and then to close hauled on the opposite tack. This means that you are travelling through perhaps 60 - 100 degrees and your sails, having been trimmed in on one tack, flap for a short while and then are trimmed in on the opposite tack. 

During a gybe you are likely to be travelling through the same sort of angle (i.e. 60 - 100 degrees) but this time, because you are sailing downwind, your sails are going from being fully eased out on one tack to fully eased out on the other tack. Furthermore, where a sail is attached to a spar (like a boom) which is attached at the front end to a mast, then a tack will mean the boom simply flaps before pivoting around its frontmost point (the gooseneck) in a relatively gentle motion. 

In the gybe, the windward end is not attached to the mast (as it is in the tack) and therefore the boom has a propensity to slam across the boat violently if the wind moves from one side of the sail to the other without the mainsheet being properly controlled. This is known as the crash gybe - and this is why gybes can be dangerous.

What is a typical gybe procedure?

To avoid the violent crash gybe we therefore have a procedure whereby we centre the mainsail by trimming in the mainsheet and centering the boom before we gybe the boat (move the stern of the boat through the wind). 

During the tack, the mainsail trimmer might simply adjust the traveller so as to trim the sail for the new tack and to maintain speed. In the gybe she will need to secure the main traveller so that it is not ‘dynamic’ and won’t slap across the boat during the gybe. Then, timing the trim with the helm turing downwind towards the dead run, the mainsheet trimmer will pull in armfuls of sheet making sure to work on the right side of the mainsheet winch or pulley system. 

As the helm gets to the dead run the mainsail should be centred or very close to centred and the slack in the mainsheet should be taken-up. The helm then pushes the helm over and calls gybe-ho as the wind filling the main transfers over to the other side of the mainsail and the leech flips over. Once the leech has flipped, you are gybing! 

As the boat gybes, the mainsail trimmer must quickly ease the sheet to allow the boat to both accelerate and to stop the boat wanting to round-up to the wind. Failure to do so will almost certainly result in the boat rounding-up violently to windward, especially on a breezy day or on a light and/or shallow draft boat. Remember, you are sailing downwind, so you need to trim accordingly.

The process will usually be guided by the helm and the commands used may vary but are likely to follow something like this;

1: ‘Standby to gybe’  -  everyone gets into position and when ready shouts ‘ready’
2: ‘Helm Over’  -  indicating that the helm is turing the boat further downwind towards the run.
3: ‘Gybe-ho’  -  Indicates the leach of the mainsail is flipping across and the wind is passing from one side of the boat to the other.

On ‘standby to gybe’ the mainsheet trimmer should have centred the main traveller and locked it and maneuvered to a safe position where she can quickly take in mainsheet and is not exposed to the boom, mainsheet or traveller if there is an accidental, premature gybe.

On ‘helm over’ the mainsheet trimmer pulls in armfuls of sheet as the weight comes off the main sheet and the boat ‘sits up’. Timing and technique are everything here. When teaching novice crew on day 1, many of our instructors will choose to handle the mainsheet so as to control the speed of the gybe and protect the crew from errors on the helm.

On ‘Gybe-ho’ the main sail will gybe and the boom will fall over from one side of the cockpit to the other. Keeping heads down, the mainsheet trimmer will quickly ease the mainsheet to trim. We’ll ignore the headsails here as the procedure will vary dependent on what type of headsails are being flown at the gybe.

We will address other jobs in the gybe later in this article.

What are the potential dangers associated with a gybe?

The obvious primary danger in the gybe is the risk of injury to the crew or damage to the boat due to the potentially violent transfer of loads from one tack to the other. This can largely be mitigated by the techniques set out above. However, other dangers also need to be considered. They are;

  1. If the mainsheet traveller is not properly secured it may slap across the boat and trap carelessly located feet, fingers, toes and other body parts!
  2. Too many crew get into a nasty habit of steadying themselves in a small boat cockpit by holding the mainsheet at or below the block. It only needs a slight ease of the sheet, or a rock of the boat in a seeway, and you can see your fingertips nipped in the block - it’s happened to many a good sailor!
  3. Head injury on the boom is an obvious danger and the forces involved are considerable. What is less well appreciated is that it’s not just the potential for a fractured skull, but the very real danger of a broken neck either through direct contact with the boom or by contact with with the whipping mainsheet. The snatch loads on a mainsheet can be enormous, and enough to break a boom. If they can break a boom, think what chance your neck would have!
  4. Going overboard, either through losing balance during the gybe or from being in the wrong place during the gybe (the classic is to slide across the coach roof, out of control). 
  5. Being hit by the kicker or other rigging such as headsail sheets, spinnaker poles, etc
  6. When sailing, especially when sailing downwind, always be thinking about mitigating risks.


Why do racers stand on the coach roof in harm’s way?

In an ideal world the use of a boom preventer will help to stabilize the boat downwind and help reduce the chances of a crash-gybe. However, if you are racing and in close proximity to other boats you may find yourself suddenly needing to gybe (for example if on port tack alongside a competitor on a starboard tack!). 

A rigged boom preventer in these circumstances might, therefore, be undesirable as it reduces mobility. In these circumstances, especially when sailing deep downwind or in light airs or choppy seas or cross-seas, you will often see crew (normally the mastman) on the coach roof, leaning against the boom so as to keep the mainsail working and to stabilize the boom and/or reduce slapping. 

There are clear dangers associated with this practice but if the technique is employed it’s critical that the mastman stays in a relatively safe position aft of the kicker’s reach and in a place where he or she can quickly ‘bail out’ if he feels pressure on his back. Secondly, he should plan for eventualities. If he is swept up by the boom, will he go clear over the side or be squashed into standing rigging? If the latter, do you really want to be there? And third, are you wearing a lifejacket? If you are, great, but then do you want to be clipped on? In simple terms, I’d suggest that if you are feeling it prudent to be clipped on, you shouldn’t be standing on the coach roof in the first place! It is, if anything, a light wind technique only.

Why don’t we just wear helmets? Some people in today’s ever more risk averse world consider helmets to be an obvious choice, although they are very rarely worn on sailing vessels other than very high performance catamarans (such as have been used in the America’s Cup). 

Given the social nature of sailing, it does seem overkill for most situations, but there are other issues worth considering too. Namely, it can be convincingly argued that wearing a helmet reduces one’s sensory awareness, both hearing and spacial, and gives its wearer a false sense of security. Secondly, as has recently been evidenced in boxing, sometimes a glancing blow to a skin-covered scalp might cause less damage to the brain and the spinal column than a more solid blunt trauma to the helmet-clad head. 

I would say the jury is still out and you’d be better advised to place yourself carefully on the boat and keep your wits about you at all times.

How can we otherwise mitigate the risks?

When sailing downwind there are several things to consider. They are;

  1. Always move around on the high side (windward side) of the boat.
  2. Stay clear of the cockpit and well clear of the track of a whipping mainsheet when sailing deeper than a beam reach. On many vessels staying clear of the cockpit and aft the helming station is considered prudent. Think about where is ‘safe’ to sit on your vessel and advise your crew accordingly.
  3. Always wear lifejackets in case you fall overboard or are knocked overboard unconscious.
  4. Have an easily deployed and reliable system of bracing the mainsail and boom when sailing downwind. This might take the form of a ‘boom preventer’ or boom damping mechanism. Make sure your crew know how and when to use it and how to quickly and safely adjust and/or de-rig it.
  5. Brief your crew of the potential dangers before you go to sea and remind them whilst sailing.
  6. In very breezy conditions or when you are carrying a large amount of sail (e.g. during racing) you should have someone covering the kicker (or vang) and have it on a winch. During the gybe the vang should be eased. This will reduce the snatch load during the gybe, help protect the rig, boat and sails from unnecessary damage and reduce the likelihood of rounding up and broaching.


As with everything else in sailing, brief your crew well, practice continually and think ahead. And if it’s really too windy to gybe safely, simply tack and then gently bear away to course. Their is no shame in ‘the chicken-gybe’ despite its name!  Sail safe.