Canal Boat Propeller (Replacements and Maintenance)

Let’s be honest, our waterways are not exactly flowing springs of the cleanest mineral water. Some are hundreds of years old and as a result have collected a fair bit of detritus. A lot of this junk is just floating along waiting to foul up your canal boat propeller. In this article we are going to take a quick look at what to do about it.

Canal boat propeller frequently asked questions

Clearing a Canal Boat Propeller.

Ok first things first. Accept it. Because it is going to happen. It’s inevitable. It is how you deal with it that counts. Let’s look at some common questions and see if we can get a few answers.

What is Likely to Obstruct a Canal Boat Propeller?

Well how long is a piece of string? Propeller length obviously. Fishing line is one that is popular, but by no means exclusive. Other things might be weeds, lines and a real favourite (which thankfully is becoming much less common) submerged plastic bags.

How Do I Know When My Canal Boat Propeller is Fouled?

It’s actually pretty obvious, especially if you know your boat. You’ll notice a marked loss in power and speed for a start.

Speed? How? I don’t have a speedometer.

At lower speeds the rudder is far less effective. So, you will notice that the steering feels a lot ‘looser’ than usual.

There are other signs too. The engine will probably protest loudly. Listen for straining noises or a higher pitch to the engine. Watch the exhaust too. If you have got something stuck around your canal boat propeller then there is likely to be black smoke produced as your engine burns more oil when under strain.

How Do I Clear a Fouled Propeller?

Well the first thing you need to do is minimise any further damage or strain to either the propeller or the engine. So, pop the boat into neutral. This disengages the propeller and stops it spinning and making everything worse.

Consider using reverse (slowly) if something has wound around your prop, by putting it into reverse you might be able to unwind it, and then it can clear itself. Pay particular attention to the sound of the engine as it acts as a great clue as to when your prop is clear.

This Hasn’t Worked. What’s Next?

First make sure you and your boat are safe. If possible, move your boat to an area where it can be safely moored.

Next you are going to get a bit ‘handsy’ so it is VITALLY IMPORTANT that you turn the engine off (and remove the key to prevent anyone from starting it whilst you’ve got your digits stuck in what could become a blender).

Look for your boat’s weed hatch. You’ll normally find this miniature trap door located directly above the propeller (well you’d hope so as this is exactly what it is for). Unscrew the fixings, remove the cover and with any luck you’ll be able to see what has obstructed the prop.

Once you have removed your head from your hands, you’ll be able to access the canal boat propeller in order to remove the debris. This can often be done by hand (be careful with fishing line as often there are a few hidden hooks which can be supremely sharp). Or failing this some decent kitchen scissors or garden secateurs make light work of most canal bound junk.

Once the debris has been removed, make sure you dispose of it (don’t throw it back in the canal for another boater to fall victim to the same misfortunate that has befallen you). And of course, don’t forget to close and secure the fixings back over your weed hatch.

It is worth turning over the engine and making sure all is working correctly before continuing on your way. Don’t blast it at full power ‘just to see if it is working’. You might cause more damage if the obstruction is not fully cleared. Instead work your power up slowly, with any luck your engine will be singing again.

If you aren’t sure it is worth perhaps calling for some professional help. OK it’s not cheap. But neither is a blown gasket or new engine.


It is bound to happen at some point. Expected some might say. There’s a reason why boat manufacturers build boats with weed hatches. By ensuring your canal boat propeller is clear you can look after your engine and ensure that you have hassle free cruising. Just remember the safety advice we have given above. What’s the worst fouling you have seen on a propeller? Why not leave a comment below?




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