Tom Cunliffe explains the mechanics of gybing, what can go wrong, and shows you how to perform a flawless, fearless gybe every time

How to gybe safely and easily

Tom Cunliffe

Tom Cunliffe

If you’re one of the many sailors who also rides a substantial motorcycle, you’ll be fed up with people telling you that your machine is dangerous. I know I am. Why, we bikers wonder, can’t folks realise that there is nothing inherently hazardous about the machine? Peril only arises if it is ridden unwisely. Gybing a yacht is just the same. Gybing is part of sailing a fore-and-aft rigged vessel and, unless we revert to square rig, it always will be. Handled in a seamanlike manner, it is as safe as tacking. Take liberties with it and, like the bike, it can lead to some nasty experiences.

When I tell the ‘bikes are dangerous’ brigade that I ride defensively, they counter by pointing out that while I may take care not to stick it in the ditch, I can’t rely on other drivers to behave themselves. The answer to that is simple. Don’t let them get close enough to hit you. Pretty much the same goes for the idea that gybing is innately dodgy. The old chestnut that anyone can be caught by a sudden wind shift is largely spurious. If we are close to running by the lee in a stiff breeze and an unintended gybe looks like bad news, don’t just hope for the best. You’ve two safe options. Either alter course and gybe under control in good time, or drop the main and sail serenely on under genoa only.

I’ve gybed all sorts of different boats. Racing dinghies are nearly always slam gybed. Screw that up and you’re swimming. The 36ft race boat I drove in the early 1980s had the sort of insane rig that was supported by two sets of running backstays with a masthead backstay that did more to shape the mainsail than hold up the spar. If the poor soul on the main runner blundered when gybing in a serious wind with the spinnaker up, the whole rig went straight over the side, so you hove in the sheet and kept it there until the runner-men had sorted themselves out. And as for the big gaff schooner… don’t ask! Compared with these, gybing our boats today is easy, but it does carry the potential to go badly wrong.

What can go wrong?


A bad gybe puts huge loads on the rig, not least the gooseneck

A bad gybe can involve smashing the end off the traveller track, cracking the gooseneck, ripping a batten pocket and anything else you can imagine. I once snapped an 8-inch diameter wooden boom gybing against a preventer that had been foolishly rigged halfway along its 30ft length.

I didn’t mean to gybe, but it was a black, foggy night and the fishing boat I had allowed to creep up on my weather bow left me little choice but to run by the lee and pray. Prayers are rarely a substitute for positive action. Perhaps unsurprisingly, on this occasion mine went wholly unanswered.

The problems with gybing fall into two categories: boat control and personal injury.

Boat control


If the helmsman does a bad job of the gybe in a decent breeze, it’s very likely to end in tears – and bills

Because they work ‘off-centre’, the sails on a yacht confer a sort of ‘helm bias’ that makes the boat want to swing up towards the wind. We correct this, either actively or automatically, by applying varying degrees of weather helm. The essence of a gybe is that, as the wind crosses the stern of the boat, the canvas blows from one side to the other, carrying the bias with it. If we fail to correct the result of this quickly enough, the boat will try to round up or broach.

Any yacht’s hull is perfectly balanced when she’s sailing bolt upright. When she heels, her underwater shape becomes to some extent unbalanced – some more than others. Like the sails, this also creates weather helm. When heel is suddenly transferred from one side to the other, as it may well be in a gybe, the hull-induced weather helm flips across, adding to the efforts of the sails to swing the boat into the wind.

The sum of these two natural causes is that, left to her own devices, a yacht gybed in a hard breeze can very easily broach – that is, swing broadside on to wind and sea in an uncontrolled manner. At best, this is very unpleasant. At worst, it results in a knockdown. All of this can be neutralised or even discarded if the boat can be kept on her feet and under full helm control. All gybing expertise is centred on achieving this end product.

Personal injury

The mainsheet and traveller, if unsecured, can crash across with tremendous force. Stay well clear

The mainsheet and traveller, if unsecured, can crash across with tremendous force. Stay well clear

Sailing is alive with stories about crew being injured or worse by the boom or the mainsheet assembly in a gybe. These tales are true. If the mainsheet and its traveller are close enough to the crew to be an issue, they must be controlled for security to be guaranteed.

Booms have also taken their toll when left to their own devices, causing concussion or death from a direct hit, or knocking people clean overboard.


Don’t sit on the coamings. In a broach, your brief flight could end on a winch to leeward

If a boat is allowed to fall off her feet at the moment of gybe in a stiff breeze, it is likely to be followed by a broach or partial broach. The result is that the boat lurches violently. Cases are on record of crew who imagined themselves safe on the windward side of the cockpit being tossed to leeward like rag dolls. If they land on a winch, injury is likely.

Safer gybing

Now we know what can go wrong, we’re in good shape to make sure it doesn’t. For our article, we used a standard sloop-rigged Bavaria 40 with no running backstays. Kieran, Chris and I applied our collective experience.

Typically with seamanship, there may not be a perfect answer for all occasions. The best position is to understand the mechanics of what’s happening, be aware of the available options, then consider the conditions before deciding what’s best for the boat we have and the crew that are on deck. There are two essential methods of gybing the mainsail, and one fall-back method, and we’ll look at all three over the page.

Fully-controlled gybe

The process


1. Steer a touch above a dead run to cut the apparent wind


2. When you feel the mainsheet go lighter, haul the boom amidships


3. When the leech lifts, you’re gybing


4. As soon as you can, ease out the mainsheet on the new gybe

This is the classic, safe method, which I personally favour. The devil is in the detail, however, and significant drawbacks must be understood and countered.

The objective is to keep the boat moving straight and on her feet to avoid broaching. Given a well-balanced hull, there’s a great deal to be said for controlling the boom fully.

If any bar-room expert tries to suggest that this is a formula for a guaranteed broach, advise them gently that the mainsail is in fact stalled throughout this procedure because air is flowing from leech to luff. It is therefore not pulling nearly as hard as one which is full. Once it’s amidships, so long as the helm keeps steering dead downwind, broaching tendency is minimal.

Opposite lock – the big secret



1. Keep an eye on the leech and bring her stern slowly through the wind

2. Apply ‘opposite helm’ to prevent a broach, and keep her dead downwind

2. Apply ‘opposite helm’ to prevent a broach, and keep her dead downwind

All of us who have driven our cars with a little verve – and what sailor hasn’t – understands that when we go into a slide and the back end starts hanging out, we apply opposite lock to the steering, turning the front wheels into the skid. Exactly the same technique is vital if a boat is to gybe smoothly and stay on her feet. Approaching the gybe, she is steered slowly but steadily to leeward to bring the wind across the stern. As soon as the leech of the mainsail starts to flick across, a gybe inevitably follows.

You know that the balance of the boat is about to shift dramatically in the next second or two, so pre-empt it. Turn the helm positively in the opposite direction to ‘meet’ her before she starts swinging into a broach. The object is to keep the boat upright on her feet and sailing dead downwind as the boom comes over. This timely application of ‘opposite lock’ is the big secret of gybing safely.

Secure the mainsheet traveller


Make it part of your gybing routine to secure the traveller

It doesn’t matter what method of gybing you plan, if you have a mainsheet traveller it absolutely must be secured at both ends and any slack in the tackles taken up. Injuries caused by travellers – especially those in the cockpit – are among the commonest in gybing. Make it a drill to check before you gybe. ‘Traveller secure? Right. Stand by to gybe!’



‘Ready about!’ heralds a tack; ‘Stand by to gybe!’ means a gybe. Clarity is all

My first boss in a proper sailing school back in the 1970s pointed out that if we always said ‘Ready about’ when tacking and ‘Stand by to gybe’, there could never be any ambiguity of orders. He was right. No namby-pamby ‘prepare to gybe’ on my yachts, and no ‘ready to gybe’ either. It’s ‘stand by to gybe’ every time, and ‘Gybe-ho’ as the leech of the main inverts and there’s no turning back. Save ‘ready’ for tacking!

What about the genoa?


When the main’s gybed and set up, pass the genoa to the new winch

Compared to the mainsail, the genoa is child’s play. The only thing that can go wrong is that the genoa flies out ahead of the forestay and wraps around it with wretched consequences. The solution? Never, ever, let the genoa sheet fly.

Wait until the mainsail has successfully gybed and is set on the new tack. Then pass the genoa under control from the old winch to the new. It will fall quietly and naturally through the gap. It’s easy, low-stress and removes half the worry from any gybe. Nobody has to multi-task and it never fails.

A fun exercise

1. As the leech flips, apply opposite helm to keep her honest

1. As the leech flips, apply opposite helm to keep her honest


2. Steer by the lee until the leech flips, then opposite helm again

To master the gybe, run the boat off the wind with plenty of space to leeward. Heave the sheet in tight and gently gybe the boat. Don’t ease the sheet. Now gybe her back again, and so on, running straight and dead downwind all the time. After a dozen or so gybes you’ll have mastered the helming technique and you’ll never dread gybing again.

Slam gybe

If the mainsheet is anywhere near the cockpit, you absolutely must gather it up and throw it to leeward

If the mainsheet is anywhere near the cockpit, you absolutely must gather it up and throw it to leeward

Aboard the 35-ton pilot cutters of the Bristol Channel before World War 1, nobody was interested in heaving in 120ft of mainsheet on a dead run in a breeze. It was a two-man job with only one available.

The preferred method of gybing was to let the boom out to the shrouds, steer carefully round until the mainsail was thoroughly by the lee, and keep on steering thus until the leech finally lifted and carried the sail across with its thirty-foot boom and solid gaff. As the boom came over, the helmsman kept his bottom on the tiller, grabbed the parts of the mainsheet, which were sited on the deck abaft where he stood in the cockpit, and threw them bodily out on the new lee side. This made sure that nobody and nothing was caught in the bights of the mighty mainsheet. As for the boom itself, it was a pussycat, because, by the time the main was sufficiently by the lee for the sail to gybe, the boat’s attitude to the wind on the new gybe wasn’t far from beam-on. The sail therefore feathered before it hit the shrouds. Then the sheet was trimmed and away they went.

I suspect that this worked better on gaff rig than it often does on Bermudian, but it saves a lot of trouble in very light going, where it is often the method of choice in a modern yacht. Even in a gentle breeze, however, the mainsheet, if it’s anywhere near the cockpit, absolutely must be gathered under control because it remains a hazard that can develop some serious momentum.

Duck and cover!


1. First, wind on plenty of vang to tighten the leech


2. Secure the traveller, steer dead downwind, then slowly bring the boat’s stern through the wind


3. When the leech flips, you’re gybing. Apply opposite helm – and mind the mainsheet!

4. Set your course, gybe the genoa, and thank the Lord

4. Set your course, gybe the genoa, and thank the Lord

The problem with a modern cruiser is that, unlike the ponderous gear of history, our kit is a lot more skittish. Whilst I must have handed across the parts of my old cutter’s mainsheet hundreds of times without incident, I can’t say I fancy it one bit on a 32ft yacht with a mainsheet traveller running across the bridge deck. In 25 knots that boom whips past so rapidly that nobody can guarantee to clear away the sheet as it comes, so it’s best not to try. The human cost of the ropework catching a crew member awkwardly as it flies by can be literally horrific, so I cannot recommend this method with such a mainsheet arrangement.

However, if the sheet is safely sited well forward of the cockpit, a straight ‘slammer’ can succeed after a fashion, so long as the gear is bulletproof. Given a touch of opposite lock, the boat should be easy enough to steer because, so long as the sheet has been fully eased, the main will be right ‘off’ immediately after the gybe. This makes hull imbalance less likely and also reduces any broaching tendency induced by the mainsail. The downside is the danger of damaging the gear, but with the vang on hard to make sure the boom doesn’t rise up and strain the gooseneck, this is not likely.

That said, as in all things at sea, it’s ‘horses for courses’. My own boat has her mainsheet so well out of harm’s way that it would be virtually impossible for it to catch anybody in the cockpit. However, my in-boom reefing means the gooseneck, while a marvel in stainless steel sculpture, is more vulnerable than a straightforward arrangement. I’ve tried slam gybing in a breeze once or twice. The crash made me shudder and I don’t do it any more.

Another major factor is aft-swept spreaders. They prevent the mainsail from being squared away properly or feathering after a gybe. This makes damage from the boom whacking the standing rigging a quantifiable hazard. For extreme examples, slam gybing is likely to end in tears. You can only try it and see. The Bavaria we used was marginal. In 20 knots it wasn’t quite an issue, but I’ve sailed boats where it gave me nightmares. Forewarned is forearmed.

The fall-back method – wearing round


1. In lively conditions, if you’re worried a gybe may cause damage, you can ‘wear round’


2. Put the helm down to bring her head up into the wind, then keep going through the tack

Bear away and be quick to ease the mainsail, then sort out the genoa for the new gybe

3. Bear away and be quick to ease the mainsail, then sort out the genoa for the new gybe

Square riggers had big issues with tacking. Gybing for them was easy. If the skipper was in any doubt about tacking through the wind, he’d give the order to ‘wear ship’. The helmsman steered to leeward and round she came onto the new tack, quietly bracing her yards. She lost vital ground, but was safe and sure.

For some reason, the term ‘wearing round’ has been transferred to fore and aft rig, where it means the opposite. We don’t like gybing but tacking is easy. If it should turn out that you are stuck with a slam gybe and you don’t fancy it, there is always the option to come up to the wind and tack round instead. It’s messy but it’s safe, and it’s always been known as ‘wearing round’. Strange, but true!

Safety and the crew


Brief the crew beforehand, so they know where to be and what to do

Crew safety is as important as looking after the boat. Some might say it is more so and I wouldn’t argue. I’d point out, however, that if the boat is properly controlled, crew safety largely takes care of itself. Here, based on my own experience and also on court cases in which I have been consulted, are the matters you ought to consider.

Unless you have someone you can trust absolutely to steer dead downwind until the gybe is complete, take the helm yourself! Then you’ll have the best overview and can make absolutely sure nobody is in harm’s way.

Brief the crew, especially inexperienced people. They must know exactly what is going to happen, and when.

Nobody must be in a position from which they could be thrown bodily in the event of a broach, or be caught by the boom, mainsheet, or traveller. These are vital considerations. Court cases often turn on them. Make doubly certain that any cockpit traveller controls are absolutely secure.

Check the traveller is secure, then check again. If it’s loose, there will be trouble

Check the traveller is secure, then check again. If it’s loose, there will be trouble

The default is not to slam gybe in a breeze with a cockpit-mounted mainsheet because it can, literally, be lethal. If you must slam, give the sheet a clear passage and, if practicable, have a steady, reliable hand to grab the parts and control them as they whip across.

One final point: if you find yourself inevitably closer to the sheet than you’d like, crouch with head right down and arms at your sides, so that, if the falls should try to grab you, there’s nothing for them to snag.

How boat design affects the safety of a gybe

Most modern yachts operate one of three mainsheet systems: boom end, cockpit traveller, or coachroof. All have virtues and drawbacks.

Boom end traveller


Good for trimming and keeps the forward cockpit clear. However, the traveller and mainsheet are to be watched, and the boom is sited over the cockpit, leaving anyone standing up at risk from the knock-out blow

Cockpit traveller

This is the gybe bogeyman. Anyone caught in the wrong place can be in dire danger of being pinned by the mainsheet, injured by an unsecured traveller running amuck, or garrotted by the sheet parts as they whip across

This is the gybe bogeyman. Anyone caught in the wrong place can be in dire danger of being pinned by the mainsheet, injured by an unsecured traveller running amuck, or garrotted by the sheet parts as they whip across

Coachroof traveller


The safest option for families and beginners. It carries serious drawbacks for mainsail trimming but it does keep danger well out of the way. It’s more than likely that the boom will also be clear of the cockpit with this arrangement, but if it isn’t, you know what to do!