Accident reports provide a stark reminder of the dangers at sea, but to ensure safe downwind sailing, we must learn from mistakes, explains Rachael Sprot.
A crash gybe is one of the most destructive incidents that can occur on board. The level of power unleashed when the wind strikes the mainsail from an unintended direction is immense, and the rapidity with which it happens leaves little time for evasive measures.
Over the past two decades, several tragic crash gybe accidents have occurred, analyzed by the MAIB and other organizations, which reveal deeply sobering insights.
While studying accident reports is routine in aviation, it is not as common among sailors. Nevertheless, these studies are crucial for recognizing the risks we face at sea, understanding how accidents transpire, and the insights gained can improve our skills as skippers. The MAIB focuses on dissecting the causes of incidents without assigning blame.
Most sailors have likely experienced an unexpected gybe at some stage, albeit without severe repercussions. Instead of assuming we are immune to similar mistakes, it’s perhaps wiser to consider that we are not, prompting a thorough examination of these reports to uncover recurring themes and strategies for safe downwind sailing.
Case Study 1 – Liquid Vortex, 2011
In 2011, the Beneteau 40.7, Liquid Vortex, was in the Myth of Malham Race when an accidental gybe led to serious injury for one crew member. The race begins in the Solent and travels west, passing Eddystone lighthouse before returning to the Solent.
The vessel was sailing downwind on the homeward leg in a West F6 when its spinnaker ripped. The damaged sail was brought down, and a heavier spinnaker was prepared but became tangled during hoisting. At that moment, the headsail was not deployed, and no preventer was set up.
The first mate went forward to resolve the sail issue, while the skipper remained in the cockpit but had difficulty sorting out the wrap. Noise from the flapping sail made communication challenging between the cockpit and foredeck. Growing impatient, the skipper decided to go forward himself.
He left an unseasoned crew member in charge of the helm, instructing her to steer at 040°, which approximated a beam reach. Despite noticing a fishing boat approaching, he believed it wouldn’t pose a threat. The helm and another crew member in the cockpit became increasingly alarmed about their overlapping paths and sought guidance from the skipper. He shouted instructions to pass ahead, gestured for a port turn, and advised them against gybing. However, the helm unexpectedly turned starboard, resulting in an unintended gybe.
The traveller on the First 40.7 is located just in front of the helm, and during the gybe, the mainsheet swung back, hitting the helm and knocking her to the cockpit floor, where she remained unresponsive. Another crew member took over the wheel, accidentally initiating a gybe again. A Mayday call was placed, and the injured crew member was airlifted, during which a winchman fell overboard and had to be rescued by hi-line from the water.
MAIB Analysis
The report concludes that communication challenges existed between the skipper on the foredeck and the helmswoman in the cockpit and that her uncertainty about the skipper’s intentions could have been avoided if the skipper had stayed in or returned to the cockpit until the fishing vessel was clear.
The MAIB also pointed out the skipper’s competitive nature, stating that he "drove his boat and crew hard." Considering the presence of inexperienced crew members, many suffering from fatigue and seasickness in demanding conditions, a "more cautious and encouraging approach was warranted," as stated in the MAIB report.
Case Study 2 – CV21
During the initial leg of the 2015 Clipper Round the World Race, CV21, part of a fleet of twelve identical Clipper 70s, suffered a fatal crash gybe 120 miles west of Portugal.
The boat was on a broad reach with NNE winds of 20 knots under moderate sea conditions. With the full mainsail, Yankee 1, and preventer rigged, changes in watch occurred at 2200, where the oncoming watch leader deemed the boat a "bit lively." The off-going leader disagreed, claiming no issues during his watch.
By 2330, winds had intensified, gusting to 30 knots. One of the more novice helmsmen was at the wheel. The skipper, who was below deck, and the watch leader agreed to reef. As the watch leader left the helm to brief the crew, he stayed clipped on behind the traveller but was poised in a danger zone when the boat gybed unexpectedly.
The report notes, "The helmsman could not regain control of the yacht’s heading before a second gybe flipped the boom back to port," while "a crew member observed the boom preventer was free." After the double gybe, the watch leader was found motionless in the cockpit, tragically never regaining consciousness. The vessel diverted to Portugal, where a postmortem determined he had suffered a broken neck.
MAIB Analysis
The MAIB audit indicated that before the incident, "the apparent wind speed of 15.7 knots was nearing the 16-knot limit recommended by the sailmaker for the Yankee 1 headsail." With wind speeds increasing, the helmsman struggled to maintain the yacht’s heading, veering off course by as much as 50°. They asserted that "it would have been wise for… [the watch leader]… to replace the helmsman with a more seasoned crew member," while his decision to reef was timely.
Regarding the watch leader’s proximity to the traveller, the report stated that prior race training and safety briefs addressed such hazards, but it’s unclear why the watch leader was positioned there. The report speculated he may have been distracted by pre-reef planning and neglected the potential danger zone. The skipper’s absence during the reef briefing, while understandable, left the deck unsupervised in a heightened-risk environment.
Case Study 3 – Buccaneer of Upnor
Crash gybes don’t occur exclusively while running downwind. The MAIB summarized an incident from August 2007 involving the Elan 333 Buccaneer of Upnor, which experienced a crash gybe while traveling from Weymouth to Poole off St Alban’s Ledge from a beam reach. Conditions were Northerly, ranging from Force 5 to 6, with gusts at Force 7.
As noted in the MAIB accident summary, the skipper had been watches over a novice helm on a close reach. Even with two reefs and the No. 1 jib set, the helmsman struggled to keep the boat on course, causing the mate to frequently "spill" wind from the overpowered sails by easing the mainsheet.
Upon needing to go below, the skipper instructed the helm to switch course to a beam reach, moving further off St Alban’s Head while the mate remained on deck. When the skipper went below, a gust hit, causing the boat to broach, prompting the inexperienced helm to turn hard to counteract. "After a while," the report states, "the gust eased, but with the helm hard over, the yacht quickly swung around to starboard and crashed into a rapid, uncontrolled gybe."
The traveller on the Elan 333 lies forward of the cockpit, just behind the companionway. During the gybe, the mate, who had been behind the traveller, was ensnared in the slack mainsheet and thrown against the coach roof, resulting in fatal injuries. He was airlifted but succumbed the next day.
MAIB Analysis
The MAIB advised that skippers must "thoroughly evaluate each crew member’s ability to competently undertake specific tasks given the current weather," especially when the skipper is off the deck.
It urged that skippers "ensure the passage plan and navigational responsibilities are clearly conveyed when transferring temporary control of the deck" and maintain oversight over inexperienced crew.
Case Study 4 – Platino
According to a report from Maritime New Zealand, the privately owned 66ft sloop Platino underwent a significant refurbishment in 2015. After three months of cruising New Zealand, both owners and three additional crew began a voyage to Fiji, over a thousand miles away. One owner, identified as the skipper in the report, had between 60,000 to 70,000 miles of experience, and the remaining crew shared similar qualifications.
The journey commenced under light winds, but by the third day, conditions escalated to 30-35 knots from the south with choppy seas. As Fiji lies directly north of Auckland, a broad reach was adopted with a preventer set, sail reduced, and the autohelm functioning well. Suddenly, the vessel crashed gybed, the boom overshooting before it gybed back again, leading to a loss of control as the preventer failed.
At that point, the helm station rested behind the central cockpit, with the traveller positioned in between. No one was at the helm during the incident, but it is believed a crew member attempted to reach it when the second gybe occurred. He was likely thrown onto the side deck by the mainsheet and died instantly from the resulting injuries.
Worsening Situation
The preventer’s failure left the boom entirely unrestrained, with the mainsheet and traveller car still attached. The report mentioned, "The boom’s motion was limited only by its contact with the shrouds on each side of the mast." The remaining crew members were then called on deck.
"Soon after arriving on the deck," the report continues, "the first crew member to arrive yelled at the skipper to duck, which she did just before seeing something fall overboard on the port side. The skipper then observed the crewmember in the water at a distance from the yacht, arm raised, as the yacht remained out of control." Tragically, the crew member thrown overboard was never retrieved.
One of the owners managed to reach the helm station but struggled to control the yacht. He just managed to keep the boat pointed into the wind long enough to furl most of the mainsail. The mainsheet and traveller car, still attached to the 678kg boom and mainsail, were likened to "a wrecking ball," damaging the helm console that included hydraulic furling controls before the mainsail could be fully stowed. The cockpit table and bimini were ultimately demolished, and the wheel bent, complicating attempts to regain control.
The crew failed to secure the boom and feared its movements could bring down the rig, which it ultimately did several hours later. The three survivors were rescued the following afternoon, more than 24 hours after the incident.
Investigations indicated that the header tank for the hydraulic fluid in the rudder drive unit had nearly run dry, with a slow leak likely causing the steering issues that spurred the gybes.
The inquiries revealed that the preventer had structurally failed in two areas; the line broke and the deck fitting it was anchored to sheared off. On the mainsheet traveller collapse, the report indicated that the system’s design and installation exceeded recommended specifications, but it was "unreasonable to expect that the traveller arrangement could withstand one or more completely uncontrolled gybes."
Platino Accident Report
While forces on a 60-footer significantly surpass those on a 40-footer, the Platino report offers crucial insights regarding preventer design. It emphasizes that the angle between the preventer and the boom is essential in reducing stress on the preventer.
If hypothetically a preventer could be rigged at a 90° angle to the boom, the load on the preventer would equal the force acting on the boom (1:1 ratio). However, rigging a preventer at that angle is impractical; the best angle achieved on Platino was 27° if secured to the bow, increasing load on the preventer by a factor of 2.4. Platino’s preventer, anchored to a block on the toe rail just behind the shrouds, had only a 6° angle, amplifying the load on the preventer by a factor of 10.
Computer simulations indicated that static loads on the preventer rigged to the bow in 35 knots would amount to 1,100kg. However, placed at its existing angle, the load increased to 4,600kg. An additional wind gusting to 45 knots would up the loads to 1,700kg and 7,000kg, respectively. While simulations may not account for real-world aspects such as shock-loading or angles from boom to deck, they elucidate the necessity of positioning your preventer line as far forward as possible.
Platino’s preventer consisted of a pennant anchored to a strong point on the boom and a lengthy extending line, which was the section that broke. While the pennant was designed specifically as a preventer, the extending line was repurposed from an older line. Even new, it was considerably weaker than the pennant. The pennant and the extending line connected via bowlines, identified as the probable failure point since a bowline can reduce a line’s strength by up to 70%.
Additionally, Platino’s preventer experienced failure at the deck fitting. Bolts securing the padeye for the block to the toe rail broke off. This padeye was not intended to be part of the preventer system and lacked sufficient strength for this purpose.
The report included data from Harken, indicating that a block redirecting a line at 30º experiences 52% of the line’s force, 100% at 60º (same load), and 200% at 180º (double the load). With Platino’s preventer rigged to the shrouds, this could lead to a load on the deck fitting and block nearing 9 tonnes.
Lessons Learned from Accidents at Sea
These reports provide thorough investigations into each accident’s causes and are essential reads. Each incident has unique circumstances, with various factors like crew interactions, weather conditions, and unexpected gear failures contributing to outcomes. Aside from the individual insights gleaned from the reports, broader lessons emerge from analyzing incidents collectively.
1. Mainsheet Hazard
It’s a common misconception that the boom poses the greatest danger during downwind sailing. Though being struck by the boom in a crash gybe could be fatal, it’s generally high above head level on most modern cruisers.
More often, it’s the lengths of slack in the mainsheet that pose greater risks. Novice crew members may inadvertently position themselves near the traveller, unaware of the potential for the mainsheet to swing through that area. Crew members need to keep clear of danger zones, and they should look out for each other by alerting anyone in unsafe positions. Establishing a clear safe line, such as ahead of the primary winches, aids crew movement.
2. Helm Experience
In the first three incidents, the helmsperson lacked experience. Downwind sailing, especially with any wave or swell, can be challenging, and untrained sailors shouldn’t be left unsupervised.
An experienced helm may even struggle with unfamiliar boats or environments, such as when transitioning to ocean sailing. If uncertainty arises, adjusting the sail plan and course to align better with crew competence is advisable.
3. Cockpit Layout
It’s notable that none of these incidents transpired on yachts with coachroof-mounted mainsheets. A traveller positioned inside or behind the cockpit significantly elevates injury risk during a crash gybe. Many modern yachts in charter fleets and sailing schools are equipped with such centre mainsheets.
However, numerous performance cruisers, racing vessels, and older boats often lack this feature, necessitating heightened vigilance during their operation. Sailors used chiefly to centre-mainsheet yachts may not be familiar with the dangers presented by the traveller and mainsheet and require additional training.
4. Distraction
In the instances of Liquid Vortex and CV21, activities outside the cockpit contributed to distractions; for Liquid Vortex, unwrapping the spinnaker, and for CV21, the pre-reef briefing.
While helm distraction isn’t explicitly addressed in either report, my experience indicates that any event occurring on deck can divert the helm’s focus and must be recognized as a risk factor. Autopilots won’t get distracted, but they may struggle in heavy winds or significant sea conditions.
5. Double Gybe
Three incidents reported more than one gybe. In the shock immediately after a crash gybe, the helm might lack control, or instinctively revert to the prior course. Regardless, all crew must recognize the threat of a second crash gybe when on deck. If a preventer is rigged and holds, a quick gybe back can recover the situation.
During a crash gybe where the boom follows through, stabilizing the vessel on the new gybe while checking for injuries and damage is much safer before attempting another controlled gybe.
6. Sail Plan
All accident scenarios involved winds over Force 5. CV21 was recorded at 11 knots SOG before the accident, meaning its apparent wind was significantly less than the actual wind. Though not specifically discussed in the reports, this discrepancy can lead to a false sense of security.
Reefing early and reducing mainsail power alleviates loads on the preventer in the event of a crash gybe, increasing its chances of functioning correctly. Sailing under headsail alone after dropping the mainsail can be a viable option, especially for short-handed, inexperienced, or cruising crews.
7. Being Over-Powered
Being over-powered increases the risk of losing control over the vessel. A novice helm often oversteers if the boat repeatedly broaches. In the Buccaneer of Upnor incident, when a gust weakens and the yacht responds to the rudder, the helm needs to straighten quickly.
In gusty conditions, an extra reef may decelerate the vessel during lulls but would help maintain control during gusts.
8. Early Warning Signs
Train crew members to recognize early crash gybe indicators: the helm feeling lighter, the vessel becoming upright yet possibly heeling the wrong way, and the headsail collapsing. Instill safe turning protocols, as turning excessively into the wind is noisy, yet straying too far from the wind poses a hazard. Encourage a cautious approach; if crew cannot maintain the desired course safely, they should alter the helm, sail plan, or route.
9. Dropping the Mainsail Downwind
Dropping the mainsail to prevent crash gybe consequences is wise, albeit difficult once sizable following waves have built up—the very conditions when you’d want to do so. Coming up enough to drop the mainsail could be perilous under certain conditions. Steering onto a beam reach with the headsail tightened may backwind the mainsail and dislodge it from the shrouds, though sea states might not permit this.
Though dropping the mainsail while downwind is feasible on smaller yachts, physically dragging the luff down is necessary since the sail will press against the shrouds. On larger yachts, this task becomes exceedingly difficult unless downhauls are rigged in advance at the reefing points. Thus, during extended offshore passages, maintaining the mainsail may become unavoidable.
Rules to Remember
- Brief crew on mainsheet and traveller hazards.
- Employ competent helms during maneuvers, including briefings.
- Identify and enforce ‘Danger Zones.’
- Supervise inexperienced helms.
- Sail at safer angles (e.g., 120° rather than 150° apparent) during other activities.
- Reef early despite potentially low apparent wind strength.
- Drop the mainsail and sail under headsail only.
- Set a preventer with robust lines and a well-planned layout.
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