Will Burton explains how preparing your yacht for the worst-case scenario can help you stay afloat for longer
Twenty miles south of Salcombe, in deteriorating weather, Timothy Meo realised that the new 36-footer he was helping to deliver to the Solent was sinking. “The engine compartment was flooded with a lot of water. Initially neither of us could tell where it was coming from.
“We found the rate of ingress reduced when we were making way, so we changed course towards Salcombe, made a Pan Pan call to Falmouth Coastguard and switched on the yacht’s two electric bilge pumps – neither of which appeared to be working.
“We took turns on the manual pump, which did work, but it was exhausting. The Coastguard were keen to send out a lifeboat, but after some time pumping, we eventually felt we were keeping up with the water coming in; so we declined their offer and pressed on.”
The deeper the hull breach, the more water is forced in. A 5cm (2in) diameter hole 30cm below the water will let in 11,000 litres in one hour. Move that hole down to 1m, and 20,000 litres of water will flow in
The yacht reached Salcombe safely and the source of water ingress was found to be an incorrectly installed wet exhaust system. Meo is philosophical about his near sinking experience. “We had a thorough handover from the yacht builder, a reputable company, and left with no reservations about making the passage.
“The assumption that a brand new boat is safe, though, is a dangerous one. We later found that the electric bilge pumps didn’t work because they were clogged up with shavings and dirt from the build process. A high pumping capacity, that’s been thoroughly tested, is absolutely essential. The boat being a unique design certainly contributed to the ‘unknowns’ about it. All of us learned from the experience, including the manufacturer. It could have been much worse.”
While it is rare, but not impossible, for a yacht’s hull to fail, mechanical failure is a more likely cause of sinking on a modern yacht. David Greening, a small craft surveyor, explains: “In a modern GRP yacht, the first three things I would always look at are mechanical.
“One: the condition of the propeller shaft seal. Two: the rudder stock, and three: the keel. Looking at both the fastenings and supporting structures. Failures in these three areas are the most likely points of failure, which can be caused by poor design or maintenance.”
As yachts have become more comfortably equipped, the number of seacocks has increased. With each comes an inherent point of weakness. “They should be inspected annually for signs of corrosion, rust and dezincification. The hoses should be double jubilee-clipped and have tapered soft-wood plugs in case they fail,” adds Greening.
So what should you do if you find your yacht is taking on water? First, you should try to determine where it is coming from. Second, reduce the rate of ingress. And third, get the water that has come in back out: in the most efficient way possible.
These fundamentals of damage control are something taught to every sailor at the Royal Navy’s Phoenix Damage Control Instructional Unit in Portsmouth. A multimillion-pound sinking ship simulator where all Royal Navy personal are trained, very realistically, in the fundamentals of how to stay afloat. Whilst there are some differences between a steel warship and a sailing yacht, they are battle-tested principles that can be used on any boat.
A manual bilge pump with good leverage is a useful addition, but what is your yacht’s overall pumping capacity?
Lieutenant Rob Manson, who runs the training facility, explains that they teach sailors to think and act fast. “With every minute that passes, the situation becomes more complicated. The more water that’s in the hull, the more unstable the vessel can be and the more likely it is to capsize. What we teach is a relatively simple skill set that can be put into practice almost anywhere on board. The training is conducted in seawater, so it focusses the mind!”
What equipment to have on board a yacht to stop it sinking is something that’s best decided after considering what a sinking might actually entail. Sailing rally safety checklists usually include soft wooden plugs for all seacocks, as well as manual and electric bilge pumps – all sensible things to have on board.
However, in recent years the number of yachts that have run into submerged objects, including whales and shipping containers, has increased significantly, posing the question: is being ‘holed’ likely to mean a round hole or more of an irregular gash.
Once floorboards and stores are floating – as here on the yacht Magritte shortly before she sank in 2016 – finding and tackling a leak becomes near impossible
One particularly impressive product is Stay Afloat – a flexible waterproof putty that can be jammed into the most inaccessible points and has proven itself to be highly effective.
It can be jammed into a failed stern gland, or seacock, seal along the line of a gash in the hull, or in conjunction with other materials found at hand.
The stern gland remains an Achilles Heel of modern yachts, explains Vyv Cox, a professional yacht engineer. “One of the largest holes in the boat, through which water might penetrate, is the stern tube through which the propeller shaft passes.
This has traditionally been sealed by a packed gland consisting of three or four turns of a woven flexible material such as graphite-impregnated cotton or PTFE. This design is reliable and rarely causes major leaks on failure, but it does have some disadvantages, resulting in the emergence of several patent seal designs.
In the vast majority of cases these are highly reliable and overcome the drips and need for greasing of the traditional type, but their failure can result in considerably greater influx of water.
“Originally, traditional gland types were solidly attached to the tube but the advent of flexible engine mountings dictated that the gland also needed to accommodate shaft movement by being mounted on a length of rubber hose. Fracture or loosening of this hose is potentially the greatest source of leakage.
“Packed glands can be over-tightened quite easily, leading to [the hose’s] disintegration. In some cases there are ‘dogs’ on both the stern tube and gland housing to prevent this. Most patent seal designs, exert far lower frictional drag, making this failure type less likely.”
If circumstances allow, stopping water coming in from the outside of the hull is likely to be more efficient as the water pressure is working with you, not against you. For this, a sail or piece of PVC matting stretched over the hole can prove effective, but only if it can be firmly held in place.
Under-bunk boards were cut, glued and drilled into place underwater on the catamaran Ensemble after she was holed
Even better is a combination of wood, Stay Afloat, and screws, which can be put together to fashion a serious patch. The essential tool to carry to make this work is an old fashioned hand drill, usable underwater, albeit slowly.
This solution carried the catamaran Ensemble over 800 miles when it was holed on a remote Pacific atoll while at anchor. Nearby cruisers came to Ensemble’s assistance, including retired engineer Ed Butt, who helped fix a piece of wood to the outside of the hull by diving underwater and driving fixings through the hull.
Interior access to the hull is another consideration, particularly when buying a new yacht. Some modern moulded interiors actually make it quite difficult to get to parts of the hull that might be holed, so the means to break through the interior quickly is an additional consideration. A weighty axe is carried by many offshore cruisers for this purpose.
An engine driven bilge pump, common on fishing boats, can shift a large quantity of water and isn’t dependent on battery power
Modern yachts are usually equipped with both electric and manual bilge pumps, but surveyors often remark that electric pumps are poorly installed, meaning they are inefficient, while manual pumps would be of little use in an emergency. The sums make difficult reading for anyone with only a standard sized pump on board.
A hole 2.5cm in diameter, 30cm under the waterline, will let in 2,700 litres of water per hour. A 5cm hole in the same position will let in 11,000 litres. Most underwater collision damage occurs even deeper, meaning an even faster ingress of water.
Being able to pump out a large volume of water won’t save your yacht on its own, but it might just buy you enough time to affect a temporary repair, or abandon the yacht in a controlled way. So how do you go about increasing your yacht’s pump-out capacity significantly?
Something that’s common on even small commercial fishing boats is a main engine-driven bilge pump. Not reliant on electrical power to run (your yacht’s batteries could quickly find themselves underwater) and with a very high pumping capacity when compared to an electric pump, they operate directly from the engine.
Another option is fitting an oversized electric pump that’s rated for continuous use, or better, having one you can deploy quickly in any part of the boat on a long lead. Another tool Ed Butt used, two 4,000 gallon per hour (gph) pumps strapped together, made an enormous difference, buying enough time to make repairs with help from others in the same anchorage.
Twin 4,000 gallon per hour pumps kept water ingress at bay for long enough to effect a sturdy repair on Ed Butt’s catamaran Ensemble
The obvious and unexplained
Despite our best efforts, incidents in the past, such as the unexplained sinking of ARC yacht Magritte in December 2015, demonstrate that well prepared and equipped yachts can and do sink without explanation.
In parallel, the risk of hitting a semi-submerged object, such as debris, sealife or a shipping container, would appear to have increased. So while preparing your yacht to avoid sinking, consider making preparations at the same time to abandon in a matter of seconds rather than minutes.
Pan Pan or Mayday?
In the event of finding out that you are taking on water, letting the Coastguard and other yachts know about your situation is wise. A Mayday should only be used if life is in ‘imminent danger.’ If you are sinking rapidly and anticipate abandoning the vessel very soon, send a Mayday.
A Pan Pan says ‘it’s serious, we need help, but there isn’t a grave or imminent danger to the boat or those on board’. Should things deteriorate rapidly, they will already have information about your position and situation.
Finding the source of a leak
- If you are sinking, locating where the water is coming from can be challenging, particularly if the source is below the waterline.
- First check that it is definitely seawater. A failed hot water tank valve on a larger yacht will result in a lot of water in the bilge! While it’s not generally advisable to taste bilge water, in an emergency, this is a quick way of determining whether it’s salty or fresh.
- Work logically through all of your boat’s through-hull fittings from bow to stern. A laminated diagram should be kept with the yacht’s documents. Be sure to include the stern gland.
- Pump as much water out as possible, this may well reveal where the water is coming from.
About the author
William Bruton, 27, grew up in Lancashire and learned to sail in 2012. He now works as a freelance skipper all over the world, specialising in Oyster yachts.
First published in the August 2017 edition of Yachting World.
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