A variety of deck hardware devices will hold a line fast, but when should one be used and not another? Graham Snook explains

Sailing would be nothing without rope, but rope would be of little use if there was no way to fix, belay or secure it. Early sailors must have quickly realised holding rope for long periods was no fun – something many yacht racers have yet to understand – and making off sheets and halyards freed their hands to do other things. With the advent of rope, came rope-holding technologies.

There may be some who abhor the thought of Yachting Monthly referring to lines as rope, or you may have sailed with someone who proclaims ‘there are no ropes on a boat’. Ignoring the bell rope, bolt rope and foot rope there is rope. Lines are rope, as are halyards, sheets and warps. When we talk about rope-holding technology, we are securing the product ‘rope’, not a specific line.

While we’re righting misnomers, many people, including me, will have been calling clutches ‘jammers’, but a clutch can be released under load while a jammer cannot. That said, many Australian sailors, including gear manufacturer Ronstan, also refer to clutches as jammers, and Karver’s KJ jammer can be used as a clutch!

Cam cleats and constrictor clutches are used to control all lines on IMOCA 60 Hugo Boss

Simple cleats

For lightly loaded control lines (up to 150kg) used without winches, it’s possible to use clam cleats, jam cleats or cam cleats if they are up to the job.

As the loads increase, and unless you have a winch for each line, you’ll need a rope clutch or jammer ahead of the winch to hold the load of one line while
you winch in another.

The mechanisms used to secure the ropes vary between manufacturers and even between ranges – depending on the loads involved. But they all operate by gripping the line as much as possible while minimising damage to the rope.

A line passing through the device in the ‘open’ position can travel in and out. Once the mechanism is closed or locked, the line can be pulled in but will not go out. Once the clutch or jammer is locked it’s always best to ease the load on the winch gradually until you know the line is secured – poorly adjusted clutches can fail to secure the line.

When pulling a line in through a clutch, while it’s usually possible to do so with a closed clutch, having the clutch open will reduce wear on the gripping surface, saving the jaws of the clutch and the fibres in the rope and making it significantly easier to pull the line through.

Before a jammer can be released, the load has to be taken off it by winching the line taut. A clutch, on the other hand, can be released under load – handy for a speedy spinnaker takedown. But, as James Hall from Spinlock explained, ‘just because you can do it, it doesn’t mean you should. Our XXC Powerclutch can release at over 2,300kg but repeatedly releasing a rope with over two tons of load is not good for boat, rope or crew.’

The lead from the clutch to the winch should be as close to straight as possible, unlike in this picture

Clutch vs Jammer

Most boats from 7.5-11m (25-40ft) will have a range of different-sized clutches depending on the loads and the rope diameters in use. As boats get bigger you start to see more jammers to take the larger loads. Choosing between a clutch and a jammer will mostly depend on the working load it will experience, your line thickness, and its purpose. For very high-load applications and lines you don’t want to be released unexpectedly, a jammer is the best choice.

There is less risk of damage, and a high-loaded line cannot be accidentally released, but you rarely see these loads on sub 40ft yachts so most will opt for a clutch, and caution.

Lines become thinner under load and with age, so if you have an 8mm line and the choice of a clutch that takes 6-8mm or 8-10mm opt for the smaller clutch if its maximum load is up to the job – it will grip the line better. Also, if you need to replace a clutch that’s on a continuous line (such as a furling line for an in-mast furling system) look for clutches for endless lines. These have split fittings that can be fitted without parting and re-splicing the line. Some designs allow the clutch to be side-mounted which is handy if the clutch is to be mounted to an upright surface such as the side of a coachroof or coaming.

Clutches allow for many lines to be taken to a single winch, giving you all the lines at your fingertips


The layout of your deck needs to be considered when fitting a new clutch or jammer. Clutches are available individually or in clusters of two, three, four or five. The lines have to enter the body of the device as straight as possible. Likewise, the exit angle to the starboard side of the winch drum must be as fair as possible too. If there is upwards or sideways loading this should be taken by a deck tidy or fairlead/bullseye, not the clutch or jammer itself.

Some clutches and jammers offer the option of operating remotely using thinner control lines. The advantages of this are the length of the highly loaded line is shorter; so less stretch and the ability to locate the hardware in an inaccessible location such as a mast top jammer for a racing yacht’s main halyard.

For the low-load applications any suitable-sized A4 stainless steel bolts will do, but for mid- to high-load use, many devices will come with suitable fixings for the maximum load.

threaded metal backing plates will take loads of the clutches rather than the cored deck

It’s very important that wherever you attach the clutches or jammers, the deck needs to be able to withstand the combined load of all the jammers and should have suitable backing plates inside. Most boats have a cored or sandwich deck that will need cutting away and sealing inside to accommodate the backing pad. See our recommended method for doing this on p83.


Jammers and clutches don’t need a lot of maintenance, just a hose down after use will help rid the clutch of rope fibres, debris the rope has picked up, plus any grit or salt. When you service your winches annually (which of course you do) it’s worth inspecting your clutches and lightly greasing any bearing surfaces, all of which will be identified in the manual.

Finally, if you plan to upgrade or replace your lines, bear in mind your poor rope clutches – they might not be designed for the thinner line diameter, higher loads or the fancy slippery outer braid on the rope. Luckily, spare parts or upgrades are easy to come by, so if the jaws get worn, polished or lose their grip they can usually be replaced.

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