Propeller Rope Cutters


Fixed rope cutter

Whether we use our boat at sea, on the lakes, rivers or canals, we all face the uncertainty of what is under the water, unseen. Plastic sheets, fishing nets and discarded or lost ropes. Every single one of these things can stop our boat dead in the water if they get caught in our propeller.

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The video above come courtesy of Motor Boats Monthly magazine and demonstrates quite nicely how the various marine rope cutters work. However, you must choose wisely. Some of these cutters require a part to be screwed to the 'P' bracket that supports the end of your propshaft. On a small boat this bracket will be too small to support the imposed load if a heavy rope needs to be cut. This kind of loading will probably result in part of the rope cutter being wrenched off possibly causing damage to the 'P' bracket and propeller shaft. The one featured below is much more suitable and considerably cheaper.

Marine rope cutter

Marine Rope cutters

Ropes, nets, carpet and plastic etc wrapped around your propeller can destroy your holiday and potentially put your life in danger. The rope cutter pictured on above is the simplest type, and is also the cheapest. It is manufactured in the UK from marine grade stainless steel. It clamps onto the prop-shaft and rotates with it. The outer edge is sharpened and as rope or other fouling wraps around the prop and tightens, the blades edge cuts through and in effect chops the item up.

As you can see from the picture this rope cutter is in one piece and needs the propeller to be removed to allow you to fit it to the shaft. Removing a seized propeller involves the use of a large puller and can be made much more difficult if the rudder is in the way. In cases like this you may choose to pay a yard to do the work for you and this can be extremely expensive given current labour rates. In fact there is a very simple solution. The cutter pictured above is also available in a split version. This allows you to place the two halves together on the shaft and simply fasten two Allen screws to clamp the cutter onto the prop-shaft. This option makes far more sense than paying to have the propeller removed.

Incidentally, if you do decide to buy the split version, use the £38 version link to contact that same company. The split cutter that they produce is cheaper than others advertised.

Take a close look at the rather chunky propeller at the top of this page. You can clearly see the rope cutter immediately behind the propeller. Also note that there is a gap between the propeller and the support bracket. Without a gap here you cannot fit a rope cutter. The required gap will depend on the shaft diameter, but typically an inch is enough. If in doubt, email the supplier.

I really do doubt that you will find another cutter anywhere near the price of this one. Go take a look.

It's also good to know that these guys will ship anywhere on Earth!