A fouled propeller is every sailor’s nightmare. Whether snagged suddenly in the middle of a channel, or a drifting target for shipping, it’s a stressful situation and one that requires a calm head.

Lobster pots are better marked these days thanks to tireless campaigning by bodies such as the Cruising Association. However, the chances are you’ll still run into one sooner or later – either that or a free-floating fishing net or polypropylene line.

Mostly, it’s down to bad luck, but keeping a good watch is imperative.

Pot markers are easier to spot from the side of the boat, so if you have a spare crew, place them there and keep a particularly good lookout around headlands and in strong tidal race areas where markers may be dragged below the surface.

In many instances, however, rope caught around the propeller is your own!

Never start the engine without looking for loose ends over the side. In particular, check when leaving a berth or towing a dinghy.

It’s a worrying moment when an engine slows or judders to a halt.

There can be other clues too – for example, a tendency for the vessel to stray to one side or for the engine to sound not quite right and perhaps overheat.

If conditions allow, a yacht has the advantage of being sailed into port, and can usually do so dragging a modest length of light line.

Even so, it’s a good idea to radio the marina or harbour authority who may prefer to send out a tow.

Motorboats, of course, don’t have the luxury of alternative propulsion.

If you have twin engines, and there’s a port nearby, try motoring slowly because if you stop to free the disabled prop, the tangle may loosen enough to ensure the other one gets knotted.

With a single engine, the likelihood is you’ve come to a complete stop, and your first thought is safety. Which way are you drifting? Are there any obstacles you need to fend off? Anchor if you can, and have a boat hook or lines ready if there’s any chance of catching a mooring buoy.

A motorist wouldn’t think twice about using hazard warning lights, but not many boats carry the correct NUC (Not Under Command) signals these days.

These are two black balls by day, two red lights at night, both in a vertical line.

In poor visibility, one prolonged blast followed by two short blasts is the correct sound signal. The next step is to advise the coastguard of your situation.

If you’re in danger, or a danger to shipping, the coastguard may alert the RNLI.

Alternatively, if you’re not in any danger, a commercial breakdown service, such as SeaStart, which covers the English Channel, may be able to clear the fouled propeller or offer a tow to the nearest port.

Fouled propeller: Drifting or anchored?

Polly Philipson of Grenada Bluewater Sailing points out that the way you’re entangled will dictate the method for freeing the fouled propeller or rudder. If you’re drifting, try gently reversing on low revs.

If you’re sailing, raise the sails to control your movement – you may even be able to reach a safe anchorage. If you’re in imminent danger, call for help.

If the boat’s anchored by a line you need to take pressure off the part that’s tangled – either the prop or the rudder.

Drop your sails immediately and, using a boat hook, locate the line and bring it up to the boat.

Next, tie the line off on a cleat. This may take some effort if there is wind and tide so be careful not to drop the boat hook (she recommends carrying two).

Do not cut the line at this point as then you will have a drifting boat, which is more dangerous! Now it’s time to assess the tangle and cut it free (see below).

Safety first when dealing with a fouled propeller

Before you go anywhere near the fouled propeller, be sure to remove the keys from the engine so your crew doesn’t accidentally start it.

Even then, have a first aid kit handy because even stationary props are sharp. If you have sailing gloves, wear them.

Outboards with a fouled propeller

Solutions vary for untangling props, and if you can stay in the boat that’s by far the best option.

An outboard engine or sterndrive (where the outdrive or drive leg lies outside behind the transom) can be lifted to the beach position so you can access it from the boat.

If you’ve sucked one of your own ropes into the prop; a jib sheet or halyard, for example, you may be able to unwind it by hand-turning the fouled propeller slowly in the opposite direction.

However, even then it can be difficult to untangle.

In severe cases, the rope can actually melt into a hard ball and may need a hacksaw or other knife to clear.

Even if you do clear the prop, bear in that there may still be damage that needs attention when you get to port.

Inboards

With an inboard engine, where you can’t reach the prop, try the ‘dry’ method first.

Restart the engine in neutral, then go astern, just for a second before slipping back to neutral.

If this doesn’t free it, try going ahead. Note – only do this if you’re drifting; if you’re anchored by the line it’ll make the situation worse.

Hopefully, whatever has wound its way around will start to work free, or if you have a rope-cutter device fitted to the prop shaft that will do the job for you.

If you feel things are improving, run for a few more seconds each time.

You may be able to move slowly on, but if it keeps stalling you have a serious problem and will need to call for help.

If the rope is from your own boat, Tom Cunliffe, writing in PBO’s sister magazine Yachting Monthly, suggests having someone heave it, but warns. “You need to be sensitive here, because trying to crank the engine with the electrics when it doesn’t want to turn can burn out the starter motor as well as flatten the batteries. Think about the kit and be gentle with it.

“It’s a long shot, but before trying the starter motor method, it’s kinder to put the gearbox into neutral, grab the shaft inside the boat if you can reach it, and see if you can turn it while someone on deck tugs the rope. You could even try mole grips on the shaft to get it started.”

Fouled propeller: Hand-clearance

You may be able to clear a fouled propeller by leaning over the boat with a knife attached to a boat hook or long-handled hull scrub brush.

Gaffer tape and cable ties will keep it secure. Mark the handle so you know which way the blade edge is pointing.

Ensure you’re tethered on and wearing a lifejacket. Have a crew keep a lookout while you lean over the bathing platform.

Locate the rudder/s with the boat hook as the propeller/s will be just ahead of them.

Slide the pole in as horizontally as possible so that you can push the blade down onto the rope (cutting downward is usually easier than cutting up).

Using a sawing action, try and cut off as much as possible and keep removing any debris from the water so it can’t entangle anyone else.

When you’ve cut as much as you can, retry the engine to see if drive is restored.

For better access, you can try tying your tender alongside, though this can be a struggle in anything other than calm water.

In reality, this is very hit-and-miss; here’s what Tom Cunliffe reported back whilst trialling this method for Yachting Monthly.

“First, I lashed a short bread knife to our extending boat hook and despite a quarter-hour of hacking about, the arrangement didn’t budge a millimetre.

“The only chance of getting near the prop shaft was to lie in the dinghy with my arm right in the water. The question was, after I’d groped around and found the shaft, do I try to cut up or down? I’d assumed that ‘up’ would be best, but in practice, ‘down’ proved the superior option. I had enough purchase to do some cutting and there was plenty of space above the shaft, but it was literally a hit-and-miss affair. In real life, I’d have been in with a chance, but I could well have been at it all morning.”

Overboard

Diving under the boat to free a fouled propeller should be the very last resort.

Many sharp, hard parts on the underside of a boat can injure you, not to mention the risk of entanglement, hypothermia and cutting yourself with the knife.

Keep fins, a snorkel and mask on board, as well as a wetsuit. Not only will a wetsuit guard against cuts and bruises, but will keep you warm (in UK waters, opt for the thickest you can find, ie 6mm neoprene).

A small air bottle can allow you to dive under the boat for a few minutes, but bear in mind this means there’s more to get tangled.

Keep a line on your cutting tool, lest you drop it. A wrist lanyard is an option, but make sure it’s loose enough that if the blade gets stuck you can wriggle free.

Most sailors will have a multitool, sailing or Swiss Army knife on board.

However, Tom Cunliffe favours a robust bread knife or hacksaw. “Both are less likely to inflict horrible wounds and both will hack their way through nets, rope that’s welded itself together into a lump, or that villainous feature of modern life, the plastic fertiliser bag.”

The RYA’s Richard Falk is a free diver, former SCUBA diving instructor and a sailor with several hundred thousand miles under his belt.

He tells PBO, “I have some first-hand experience of this – and it is a pretty touchy subject! First and foremost, entering the water should not be attempted by anyone who is not experienced in snorkelling or diving, and is physically fit and healthy.

“Even then, circumstances such as sea state, water temperature, traffic, pollution, risk of entanglement and potentially dangerous sea life may be good reasons not to consider getting in the water.

“Even the slightest of seas will create a slamming effect as the bow and stern of the vessel hobby horse, risking the stern of the vessel slamming into the person in the water working to clear the prop or rudder.

In the event that an individual does decide to get in the water to clear a fouled propeller or rudder, they would want to consider the following:

• Have a ladder or boarding steps deployed prior to entering the water
• Use mask, snorkel and ideally fins
• Have a crew member on standby
• Potentially fix a ‘mermaid line’ with a float attached for the diver to hold so they remain attached to the vessel
• Engine off and ignition key removed – ensure crew are all aware there is a diver in the water
• Scan for nearby hazards before entering the water
• Use a sharp knife with a serrated blade, ideally with a blunt end to avoid accidentally stabbing yourself
• In daylight, display code flag A
• At night, display appropriate lights for the vessel, along with a bright light
• Monitor for approaching traffic and be prepared to radio if necessary or signal visually if necessary
• Alert authorities with a Pan-Pan call
• Where water temperature dictates, use a wetsuit, which will likely mean a weight belt is also required
• Consider carrying a device such as Spare Air dive kit or similar, to allow a few minutes of underwater breathing. Ensure you practice with this device before it is actually needed.

“There have been several fatalities involving people entering the water to clear a fouled prop, only to be struck by their vessel stern slamming into them, and I emphasise this is not an action that should be undertaken lightly.”

Useful kit for dealing with a fouled propeller

• Sharp knife with wrist lanyard – a serrated blade will cut quickly through a line under tension. Bread knives, hacksaws and hook knives can also be effective.
• Boat hook – useful to hook onto a line under the boat and/or attach to a knife. Carry a spare in case you drop it!
• Dive mask, goggles and wetsuit. Scuba diving equipment if you’re qualified
• Waterproof torch or headlamp –in case your prop becomes fouled at night.
• Appropriate flags and lights for Not Under Command and Diver Down
• Spare line and float to rig ‘mermaid line’ under boat n Waterproof camera capable of fixing to an extension pole

Check for damage

If you’ve managed to free a fouled propeller it’s still really important to check the hull.

Water ingress or loss of the prop shaft can be catastrophic. A fouled propeller can strip gears in the gearbox or even rip the engine from its mounts.

You’d have to be really unlucky for your prop shaft to fall out at sea – but it does happen.

Make sure you have a hardwood bung on board that fits the prop shaft’s exit hole – ideally secured with a lanyard next to the stern gland.

Rope cutters

As the old adage goes, prevention is better than cure, and prop rope cutters can certainly limit the damage or prevent a wrap altogether.

These have been around commercially since the early 1980s and there are three types: disc, scissor and shaver.

The disc cutter, also known as a rotary cutter, is mounted on the prop shaft and as the propeller spins, so does the disc, its sharp edges slicing through any tangled rope or debris.

Scissor rope cutters have two or more blades that operate in a scissor-like action.

When they meet resistance such as a rope or fishing net, the rotation of the prop shaft forces them to close and cut the debris.

Shaver rope cutters – used by the RNLI – are small fixed blades mounted on the block attached to the P-bracket.

A cylinder slides over the shaft and attaches to the front boss of the prop.

Debris is forced between the blades and the prop and as the blade spins the rope is gradually shaved through.

Rope cutters are made from stainless steel or titanium and can be retrofitted by anyone with good DIY skills, though the boat needs to be out of the water.

Many designs can be fitted without removing the prop but you’ll need to drill into the shaft to attach the cutter.

For specialist information, try companies such as Darglow Engineering and R&D Marine.

Fixing a fouled prop in the Atlantic: case study

While it’s unusual to encounter nets on an ocean crossing, two yachts got tangled in fishing gear last November whilst en-route to Cape Verde in the first leg of the ARC+ rally.

Kristian Hægeland, skipper of Najad 520 Christina, noticed what looked like ‘a veil’ in the ocean.

Further investigation with a GoPro camera and flashlight attached to a boat hook revealed the net had disabled both the rudder and the propeller.

After hours of hard work, they managed to free the net from the rudder and bring it to the bow, but it was still tangled around the propeller.

As it was night-time and the seas were rough, they were unable to deal with it immediately.

However, the nearby yacht Frenesi, a Nauticat 43, stayed on standby.

With her rudder back in action, Christina continued to sail towards Cape Verde and, when conditions allowed, the boats hove-to and put out their sea anchors.

Using a paddleboard and a long line with a fender attached to the boat, Frenesi’s skipper Martin Hakansson dived overboard with a crewmember and cut free the net with a Leatherman knife.

In an unfortunate coincidence, the following day Frenesi also got tangled in line and Martin had to dive overboard again, this time to free his own propeller.

Despite the ordeal, the two crews arrived in Marina Mindelo, Cape Verde, happy and well rested.

It’s not the first time PBO has interviewed a skipper who dived overboard in the Atlantic.

In 2020 we met ARC participant Jarmo Lohikari, who swam underneath his Hans Groop EA to free the jammed rudder.

When Jarmo surfaced he was covered not only in bruises, but antifouling – leading his daughter to comment he looked like a Smurf!

The Finnish skipper had been given a diving lesson the Christmas before by his wife Teija.

“Little did I know how valuable her gift would turn out to be,” he said. “My first dive was in the swimming pool in Helsinki. My second dive, it turned out, would be in the middle of the Atlantic…”

Prop entanglement in the North Sea: a case study

Rachel Hibberd, a comms manager for World Cruising Club, was crossing the North Sea from the Netherlands to the East Coast when she and her then-husband Steven caught a rope around the propeller of their Hallberg-Rassy 42.

“It was where the traffic separation schemes come together; where all the ships are!” She recalls.

”The first thing we noticed was the dropping revs from the engine. There was no wind at all, and visibility was poor – classic North Sea conditions.”

The boat was wide at the stern so it was hard to see what was happening. Steven decided to go overboard with a snorkel and mask to investigate.

“He was quite adventurous and the stronger of the two of us, so it made sense,” says Rachel. “He discovered the prop was fouled by a 6ft rope, around 2in diameter, with bits of nets on it.”

Steven attached himself to the boat with a rope around the waist, but encountered far more swell than he’d envisaged. He had to be incredibly careful not to bang his head under the transom.

He went down with cutting tool after cutting tool, but nothing worked.

“Perceived wisdom is to lash a knife onto a pole but you need a lot of force and we couldn’t get it to work,” says Rachel. “We tried all our sailing knives and blunted everything; hacksaw blades and various other things. The rope was plastic and very fibrous.”

Finally, after an hour’s battling, an exhausted Steven managed to free the rope with a bread knife.

Looking back, Rachel acknowledges it could have been an extremely stressful situation, but says she felt confident because it was daylight.

“There were lots of ships around but we put out regular warning calls and had white flares and orange float flares to hand. I think it was the adrenaline that kept us going. In a way, it was also kind of fun and exciting. We were young and solving a problem. I can’t say I’d feel the same excitement now, 20 years later!”

These days Rachel recommends using a GoPro on a stick like the crew of Christina did in the recent ARC+ rally.

“That way you could formulate a plan before deciding whether to do the most risky thing and enter the water,” she advises.

“You might discover the rope’s not as tightly attached as you first thought and you can free it with a boat hook or fishing gaff.”

Through her role at World Cruising Club, Rachel speaks to hundreds of sailors taking part in ARC rallies, and has found sargassum weed is a growing problem because of increasing water temperature.

“There are quite large rafts of it so you need to keep a lookout,” she says. “It’s easy to deal with – you can push it off with a boathook or reverse under sail or motor.”

What if you can’t clear the entanglement? A case study

It happens to the best of us: even PBO’s engine expert Stu Davies has come a cropper twice from fouled props!

The first time was when Stu and wife, Laura, were on the river in Waterford, Ireland.

“We felt something wind around the prop and managed to limp to the marina in the town centre,” says Laura.

“I was happy to dive under the boat but I didn’t tie myself on in case I got tangled. Instead, I attached a rope from the winch to the propeller so I had something to hang on to. It turned out to be one of those orange barrier fences with the holes in. It had wrapped itself around the propeller shaft and I managed to free it with a diving knife.”

That was 15 years ago, and since then the couple have moved their Beneteau 381 out to Portugal to enjoy some winter sun.

They were leaving an anchorage in Ferragudo when they went over the dinghy painter. The engine immediately started banging.

Due to his health, Stu was unable to dive overboard, but Laura had done it before and was happy to do it again.

“I didn’t wear diving gear,” adds Laura. “The tank just gets in the way and it’s not that far down, but it did get blinking cold! The rope had wrapped itself around the prop shaft, pushing the cutless bearing up the shaft. Laura tried a diving knife but it didn’t work.

“There was an inch of shaft exposed and the rope had wrapped itself in very tightly,” she says.

“It took a fair bit of work, wedging my back against the boat and holding my breath long enough to make the cuts. You quickly run out of energy.” After three exhausting hours, Laura succeeded with a pairing knife – one they use to peel potatoes.

“I managed to get it between the rope and the shaft. It was sharp as a razor and did the job!”

It was enough for them to hand-turn the shaft to get the engine started and leave the anchorage.

Fortunately, they had enough wind to sail 12 miles to Albufeirer, where they paid a hefty €460 for a lift-out.

Stu then removed the prop and replaced the cutless bearing.

“It’s really important to check your prop after it’s been fouled,” Stu advises. “Even if everything looks fine, a tangle may have bent the shaft and shifted the engine bearers.”

Fortunately, the boat had rope cutters, which limited the damage considerably. “Fitting rope cutters is a DIY job. If you’re capable of taking off a propeller you can easily put the rope-cutters on.”

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