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Engine

The propeller — cleaning, protection and reconditioning

Cleaning, polishing, antifouling protection and propeller reconditioning, plus checks of anodes and the shaft.

The superyacht Lady Lau in Bonifacio

The propeller works in the harshest conditions under the hull and its condition translates directly into speed, fuel consumption and vibration. Once the yacht is lifted out, the propeller is usually covered in weed, barnacles and deposits that drastically reduce efficiency. The first step is a thorough clean — best started while the growth is still wet, because dried barnacles set like concrete. Work in gloves and goggles, as shellfish have sharp edges.

Author: Maciej Baniewicz · Boat & Yard editorial team

Methodology: The material was prepared from the sources given and from practical service rules; the parameters have to be confirmed in the manual for the specific manufacturer or model.

For cleaning use a plastic or soft-metal scraper and a brush, avoiding aggressive sanding that changes the blade profile. After the rough clean, polish the bronze or steel with metal polish until the surface is smooth — a smooth propeller fouls less and is hydrodynamically more efficient. While you are there, look at the blade edges: chips, dents and signs of cavitation (small pits and erosion) point to problems worth correcting. Small irregularities on the leading edge can be gently smoothed with a file.

Judge whether the propeller needs professional reconditioning. Bent blades, uneven pitch or imbalance cause vibration that is transferred to the shaft, the Cutless bearing and the bearings. This is not fixed by eye — geometry and balance are restored by a specialist workshop with measuring equipment. If you feel clear vibration under way, have the pitch and balance checked before the whole drive train is damaged.

Folding and feathering propellers (Gori, Flexofold, Volvo and the like) need their mechanism serviced as well. Dismantle, clean and grease the joints and gears with the waterproof grease recommended by the maker, checking for play and that the blades fold freely. A seized mechanism will not fold under sail or will not open when you engage the drive, which is dangerous when manoeuvring. Pay attention to the seals, so that water and deposits do not block the moving parts.

Corrosion and fouling protection is a separate subject. The propeller and shaft are protected by a sacrificial anode (zinc in salt water, aluminium in brackish, magnesium in fresh) — replace it once more than half its mass is gone, and never paint or grease it. The propeller itself can take a dedicated antifouling for non-ferrous metals or a prop coating, but only on a perfectly degreased and etched surface, strictly to the instructions. Do not insulate the anode's contact surfaces with paint, or it will lose electrical contact.

Check the parts that work with the propeller as well. Inspect the split pin or lock nut holding the propeller on the shaft, the key and the taper — the propeller must sit firmly, with no rotational play. Look at the Cutless bearing and the shaft seal (stuffing box or lip seal) for wear and play. After refitting the propeller, make sure the nut is tightened to the correct torque and secured, because if it comes loose at sea you lose propulsion.

Finally, plan how often you do all this. Cleaning and inspecting the propeller is standard at every haul-out, and during the season it is worth diving to look under the hull if the speed has noticeably dropped. Note the state of the anodes, the date of reconditioning and the type of coating used, so you can judge how long the protection lasts. A well-kept propeller means lower fuel consumption, quieter propulsion and a longer life for the shaft and bearings.

Material prices — products and options

Indicative prices in EUR (incl. VAT), as of July 2026. Products widely available in Europe; prices depend on the shop, the pack size and consumption. The links lead to example shops that ship across the EU. Dollar amounts are converted at 1 EUR = 1.1622 USD (ECB, 7 September 2026) and rounded — treat them as a rough guide, not a price in a US shop. Imperial values in brackets are conversions of the metric figure.

Sacrificial anodes for propellers and saildrives
Folding propellers
Fixed and feathering propellers
Coatings, chemicals and small parts

Recommended materials and sources