Select Page

Propellers are complicated and repairs should be done by specialists but owners can carry out checks and some routine maintenance themselves when the boat is in the boatyard.  A propeller is critical to a boat’s performance, fuel consumption and ride, so it makes sense to keep a propeller in good working order.

Here are some checks and maintenance to carry out:

  • Clean the propeller thoroughly, removing all marine growth. Using a plastic scraper to remove barnacles is preferable to a metal one to avoid scratching the blade surface. I find mixing up a paste using white vinegar, flour and salt works well. Apply the paste to the surface and leave it for about 15 minutes. Then rinse with warm water and polish, being prepared to use plenty of elbow grease. Use superfine wire wool to help things along if absolutely necessary but whatever you do, don’t use a grinder.
  • Grease the propeller as recommended by the manufacturer’s instructions. Note that folding and feathering propellers need to be greased and the manufacturers provide advice and a kit for doing this.
  • Check the surface of the blades for any dents, scratches or nicks, paying particular attention to the tips of the blades.
  • Check for any hairline cracks in stainless steel blades, especially around the edges. These can be repaired for much less than the cost of a new propeller, but if ignored then the propeller will soon deteriorate to the point that it will have to be replaced.
  • Minor nicks and scratches can be filed smooth but take care not to grind too much as you could easily alter the blade geometry. Filing the nicks smooth will be worthwhile as the smallest of imperfections will affect performance.
  • Check the propeller and prop shaft stern bearing for signs of fishing line caught around it, which can easily damage shaft seals. This may require removing the propeller to carry out the check.
  • Check the condition of the propeller sacrificial anode if fitted and replace according to manufacturer’s recommendations – it is normal practice to replace an anode when half of it has been wasted away. Anodes do an essential job protecting bronze or aluminium propellers from galvanic interaction with stainless steel propeller shafts. A missing or badly wasted anode will result in very rapid corrosion of the propeller as soon as it is back in the water. Make sure you clean the contact point between the anode and the propeller shaft before replacing it.
  • Check for areas of pitting in the blades of faster boats that can be caused by cavitation. Cavitation is a highly complex phenomenon that causes bubbles to form on the back of a propeller blade due to the negative pressure that is created when a propeller spins at high speeds. Over time these bubbles hammer away at the blade and can cause pitting damage, which leads to vibration. Ask an expert’s opinion on the best course of action to repair the blade and whether they think cavitation is the cause.
  • If a blade has been bent out of shape or chunks of metal are missing then this will not only affect performance but also cause vibration, risking damage to struts, bearings, seals and drive shafts. The solution is to remove the propeller and ask your yard to recommend a specialist who can repair it for you. They will have the right equipment to get the propeller back into the correct shape – if it is repairable. Trying to hammer it back into shape yourself is clearly not an option.

propeller damage boat      Propeller damage boat

Vibration

There are quite a few possible causes of vibration in addition to propeller blades being out of shape and cavitation, as outlined in the checks above. Vibration from the engine and drive system is not good news and several other checks can be done at the same time as checking the propeller if vibration has been an issue:

  • Check the integrity of the bracket or strut supporting the propeller shaft and propeller. If this is at all loose then this should be looked into.
  • The propeller shaft may be worn or slightly bent, so check this over carefully for any signs of wobble when turning it.
  • The engine and shaft may be misaligned – it will probably be best to have this checked over by an engineer unless you have the skills to do this yourself.

Understanding your boat’s compass

Article submitted by Mike Rossiter, Certificated Compass Adjuster. Since the magnetic compass was first used by the Chinese...

Keel design – options to consider when choosing a yacht

Keel design is constantly evolving and nowhere is this more apparent than in modern racing yachts such as the Imoca Open 60...

What boating skills should you have before you buy a yacht?

Many people dream of owning a yacht and sailing off into the blue yonder. What boating skills should you have before you buy...

Saildrive maintenance

There are less maintenance tasks to carry out on a saildrive transmission than on a traditional inboard shaft drive system with its associated stern gear. However, there are a few critical things that require maintenance, as recommended in detail by the engine manufacturers, and should be adhered to.

First Aid Afloat – how to deal with a fracture at sea

First Aid Afloat A closed fracture does not break through the skin. An open fracture is when the bone punctures it. A...

Essential Knots: Reef knot

Essential Knots: Reef knot Use: Tying two ends of rope together, often used for tying up a bundle of loose sail around the boom. Step...

Essential Boat Spares for Safety

  Boats Spares Tool kit What you carry in the boats tool kit will be useful for many boat repairs, but you might want...

Feeling anxious at sea

  Some people feel anxious at sea. Will they be seasick? What if they get caught in a violent storm? Could the boat...

Peer to Peer yacht charter – How can you monetize your boat?

There is a growing trend in peer to peer yacht charter. How does it work? People already rent rooms, cars and bikes from one...

Essential Knots: Sheet bend

Essential Knots: Sheet bend Use: Joining two ropes together. A sheet bend is particularly useful for joining two ropes of different...

Essential boat engine checklist

Boat engine checklist Engine oil level check Even if you have checked it previously, confirming the engine oil level is up...

Repairing a leaking hull-to-deck joint

If you suspect a hull-to-deck joint has failed, then being absolutely sure where the actual leak is occurring is of prime...

Antifouling for leisure boats – Part 1

Boats that are kept afloat can very quickly become a home for small marine organisms such as barnacles, weed and slime. Applying an antifouling paint to your hull is necessary to protect it from these micro-organisms, as a fouled hull can cause problems and will slow down a boat’s maximum speed considerably if left unchecked.

VHF DSC radio – how best to communicate at sea

There are many ways to communicate with others at sea. What makes the VHF DSC radio the best form of short range...

Seized fixings and fastenings

Maintaining a boat can be a rewarding experience but at times it can also be frustrating. A prime example of this is when you come across a seized fixing or fastening that refuses to budge. Read our tips on how to release and fix them:

First Aid Afloat – jellyfish stings

  Wherever you are boating in the world I am sure you will be using a pilot guide to aid your navigation. Often in the...

Boating emergency – how to broadcast a MAYDAY emergency call

How to broadcast a MAYDAY emergency call   How to broadcast a MAYDAY emergency call if a vessel or person is in grave...

Boating Rules of the Road – International ColRegs

    International ColRegs Rule 7: Risk of Collision Anyone who is responsible for a vessel at sea, from the...

Top 5 Reasons Why an Inflatable SUP Should Be Your Next Yacht Accessory

In this article, inflatable paddle board expert Jason Paul gives the top 5 reasons why an inflatable SUP should be your next...

Distress flares – which flare, how & when to use?

How to use distress flares at sea Flares should be kept in a waterproof container in an easily accessible location such as a...

Marine diesel exhaust checks

You should inspect the exhaust system for corrosion damage regularly, especially around the injection bend. If you have noticed the engine exhaust smoking a lot during the sailing season this can also indicate a number of potential problems.

Avoiding collisions at sea – how to stay safe on the water

Boats have many blind spots, including the headsails of sailing boats. Always keep a lookout, stay safe and remember that...

Antifouling for leisure boats – Part 4

Applying antifouling. Antifouling is best applied on a dry, calm day. It is best to apply the antifouling in the middle of the day to ensure the hull is dry and as warm as possible.

Essential Knots: Figure of eight

Essential Knots: Figure of eight Use: Stopper knot, prevents a rope from being pulled through a hole e.g. through a block or...

Boat ownership

Owning a boat is a big commitment that should bring no end of satisfaction for the owner as well as the owner's family and friends. In...