The Yachting Monthly team put a range of marine knives to the test to find the best boat knife for a variety of applications

Getting your hands on the best boat knife is not a straightforward business. A blade that can slice through lifejacket harness webbing may not be suitable for severing a 12mm mooring warp that has become stuck around a bollard as you descend a lock. A knife that can saw through a polypropylene fishing line wrapped around your prop may fare less well faced with a Dyneema halyard jammed in a riding turn.

Almost every cruising yacht has a knife or three rattling around in a chart table drawer. Some skippers have a knife in a sheath attached to a point in the companionway or somewhere else easily reached. Many sailors also carry a knife in the pocket of their foul-weather gear.

But these knives often remain unused until they’re needed in anger. Apart from running a thumb across the blade to test how sharp it feels, we have little idea whether or not our chosen model will make the cut we need in a split second or a couple of minutes.

A test of man overboard recovery procedures led by Sir Robin Knox-Johnston, revealed that not all off-the-shelf blades and cutters are as effective as they might appear.

With this in mind, we collected eight different blades and tested their cutting power on lines appropriate for a number of jobs on board.

This is a single blade with a rounded tip and no other tools or features. Although the blade remains safely sprung closed, it is easy and safe to open one-handed.

The 7.8cm-long blade is serrated, but not so heavily that the knife grips a rope when it should be cutting it. We found the EZ-Out Rescue the most effective cutter in our test. Whether faced with the tough Dyneema halyard, the webbing or the awkward polypropylene line, this blade scythed through in a few seconds at most.

The blade locks well and is easily returned via a push point on the rear. At 73.7g, the EZ-Out Rescue is very light and there is a lanyard point as well as a pocket clip.

That bright yellow, reinforced thermoplastic handle is mottled for grip and Gerber has boosted this with a raised black rubber lip on each side. The overall unit is relatively thin but perfectly comfortable to use.

This knife comes with a lifetime warranty.

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This is a tool designed specifically for slashing through a safety tether in a hurry, if the tether is under load and can’t be released. Spinlock says that ‘by providing a means of disconnection, anyone wearing the Cutter satisfies ISAF and ORC recommendations’.

If that sounds unlikely, remember cases where the victim has been held under a capsized boat by a tether, or a tethered MOB has drowned while being dragged through the water. The S-Cutter comes in a protective sheath and a pouch and is small and light enough to keep in a foul-weather jacket pocket. There is also a lanyard hole if you want to keep it on your lifejacket full-time.

The tool features serrated edges for added grip in the wet. On test, we found the tool uncomfortable and difficult to get a useful purchase on. The device performed poorly in our cutting test, needing a significant amount of concerted sawing before it severed our safety tether webbing.

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This is another device designed for cutting safety tether webbing in a hurry. The blade lies on the inner corner of a U-shape in the design, which is too narrow to accommodate all but tether webbing or thin dinghy line.

The Gill model incorporates a shackle key which gives it a slightly more substantial body and makes it more comfortable to use than the Spinlock. The design includes a finger hole opposite the U-shaped blade so that cold, wet hands do not have trouble gripping the implement.

There is a lanyard hole and the tool is small enough, at 90mm long, to keep in a pocket or attached to your lifejacket belt. Gill has coated the stainless steel in titanium which is said to impede corrosion.

On test, the Harness Rescue Tool needed just one stroke to sever our tether, whether the webbing was stretched taut or held in a loop in one hand. On our guardrail lashing, it was equally effective, but too narrow for the ropes.

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The ‘Indiana Jones’ boat knife option for those who like a black leather knife pouch strapped to their belt, or to a suitable point on the boat, the Green River is a simple carbon steel blade from Sheffield, encased in a lovely rosewood handle, which is moulded for grip and comfort.

There’s no denying its aesthetic appeal and the 12.5cm blade will certainly turn heads. It also boasts a very low price.

We were assured that the blade should not need sharpening from new, but a straight edge such as this will need sharpening from time to time.

In our test, we needed at least a few seconds of cutting back and forth to sever any of the lines. Cutting the mooring warp, the Green River needed 17 strokes to cut through.

Compare that to the Gerber EZ-Out Rescue, which took one stroke.

On the polypropylene line around a propeller, we found again the Green River needed repeated sawing before it made headway. One other minus point is there is no means of securing the knife in its sheath.

Based on our test, we felt the Green River Knife was a better implement to have on board for a range of maintenance jobs.

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This boat knife is a single folding blade that is easily opened with one hand due to a thumb stud on both sides. The jet black aluminium handle has an integrated tether-cutter, but curiously, given the success of the Gill Harness Rescue Tool, we found this to have very poor cutting power on our test tether.

The 7.8cm-long knife blade itself – titanium- coated stainless steel for corrosion resistance – is rounded at its tip and has an unusual, almost childlike, bobbly serration.

In terms of cutting power, however, it was far from childlike, and proved the second most effective on test, slicing through all of our materials in a few strokes at most, equal to the Wichard.

The blade locks out securely and is folded back only once you’ve pushed in a clip within the blade slot, an idea we’ve not seen on other models but which works well ergonomically.

The Personal Rescue Knife is fitted with a clip to attach to a lifejacket or belt, and has small lanyard holes within the clip.

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The biggest plus point of this model is its locking mechanism. A thumb-operated clip locks the blade shut or open, while an additional thumb-button is pressed before it can be closed.

It sounds picky, but it’s not and with the thumb studs, the blade can be opened one-handed. Once halfway open, our test model could be flicked open all the way.

This 7.8cm-long blade has a 2.8cm-long serration at its base. The rest of the blade is smooth. We found the serration was not long enough to saw effectively at our lines and was prone to sticking.

On the guardrail lashing, the Obsidian performed well, but overall, we found it required more strokes than the other knives on test to cut through our thicker lines and tether webbing.

There are four other tools kept in the back of the handle – two screwdrivers, a bottle opener and a small file. A lanyard and pocket clip should ensure this knife does not go overboard.

The glass-filled nylon handle is smart and very comfortable to use but felt quite slippery compared to other models on test. It was also relatively heavy, at 130g.

The Obsidian comes with a lifetime warranty.

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This is a popular sailing knife, which features a marline spike, bottle opener and shackle key as additional tools to the 7.5cm-long blade. The body is fluorescent for night use and proved so on test, even after being removed from a spell in a pocket.

The chunky plastic handle is utilitarian rather than showy It’s clearly tough, but unlike some knives on test, has no sharp or jutting edges that might mark chart or saloon tables. There is a lanyard hole for this 132g model.

It is possible that our brand new model was stiffer than an example better worn-in, but we found the blade relatively difficult to deploy. Not only that, but once deployed, you have to lift up the shackle key to 90° before you can close it. It’s a secure locking system, but the shackle key itself was uncomfortable to deploy.

We found this definitely a two-hand operation and not one suited to either wet or weaker fingers. In our cutting test, the part-serrated, part straight Wichard blade performed extremely well, making light work of any of the materials.

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Although the Leatherman Wave has become popular with sailors for its wide and well-judged array of tools, for price reasons we chose a relatively conservative multi-tool, the Leatherman Fuse, with only 12 features additional to the knife.

It has a lanyard that needs to be deployed from within the body, but the 170g weight of the Fuse means you would not want it dangling too loosely around your person – better in a pocket.

The 6.8cm locking blade was extremely effective and easily deployed from within the Fuse’s body, not from the outside as on some other Leatherman models.

It sliced through all our ropes and the webbing without any problem. With pliers, wire stripper, three screwdrivers, scissors and a bottler opener, this multi-tool would cater for a lot of jobs on board with aplomb.

With none of the tools on the outside, you need both hands to use the Fuse, perhaps not ideal at sea, but the design was straightforward and all the tools easily accessible. The stainless steel body looks slippery but the Fuse fits nicely in the palm and even when wet offers solid grip. It comes with a 25-year warranty.

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