Marine anodes, including zinc, aluminum, and magnesium anodes, are sacrificial metal components used to protect the hull and underwater metal parts of boats and yachts from galvanic corrosion. By corroding preferentially, the anodes help protect more valuable submerged components such as hull fittings, propeller shafts, rudders, trim tabs, and other bonded metal parts.
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1-2 weeks delivery time Allpa ring-shaped zinc sacrificial anodes for marine propeller shafts, available for shaft diameters from Ø20 to Ø60 mm. The range includes ten metric sizes: 20, 25, 30, 35, 38, 40, 45, 50, 55 and 60 mm. Each version uses a split ring configuration for installation around the propeller shaft and is selected according to the required shaft diameter.
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$ 11.43
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1-2 weeks delivery time Navalloy streamlined collar anodes for marine propeller shafts, available for metric shaft diameters from Ø25 to Ø50 mm. The range includes six versions for 25, 30, 35, 40, 45 and 50 mm shafts. Each anode has a compact streamlined collar profile designed for installation around the propeller shaft and is selected according to the required shaft diameter.
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$ 15.65
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1-2 weeks delivery time Allpa aluminium sacrificial anodes for propeller shaft nuts, available for shaft diameters from Ø20 to Ø60 mm. The range includes versions for 20, 25, 30, 35, 40, 45, 50, 55 and 60 mm shafts. These are replacement anodes only, with a tapered cap-shaped design for fitting to the corresponding propeller nut assembly.
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$ 10.09
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1-2 weeks delivery time Allpa zinc sacrificial anodes for propeller shaft nuts, available for metric shaft diameters from Ø20 to Ø60 mm. The range includes nine sizes for 20, 25, 30, 35, 40, 45, 50, 55 and 60 mm shafts. Each version features a compact tapered cap-style body and is selected according to the propeller shaft diameter.
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$ 27.33
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1-2 weeks delivery time Allpa propeller nut assemblies with replaceable zinc anode and stainless steel locking ring, available for propeller shafts from Ø20 to Ø60 mm. The range covers metric threads from M12x1.5 to M45x3, including two versions for Ø45 mm shafts with M33x2 or M30x2 thread. Each assembly combines the propeller nut, corresponding zinc anode and stainless steel locking component.
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$ 101.73
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1-2 weeks delivery time Allpa aluminium sacrificial anodes with two mounting holes for bolt-on marine installation. The range includes Allpa 9077810 measuring 150x60x25 mm with an 80 mm hole pitch and weighing 0.42 kg, 9077811 measuring 250x65x28 mm with a 140 mm hole pitch and weighing 1.40 kg, and 9077812 weighing 3.00 kg with a 200 mm hole pitch.
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$ 29.43
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1-2 weeks delivery time Allpa aluminium sacrificial anodes with an elongated body and central longitudinal mounting slot for bolt-on marine installation. Allpa 9077815 measures 200x65x35 mm, while the larger 9077816 measures 320x65x35 mm with a 160 mm fixing pitch.
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$ 41.84
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1-2 weeks delivery time Allpa 9077800 aluminium sacrificial anode with a conical body and central recessed mounting point for bolt-on installation. The anode has an outer diameter of Ø80 mm and weighs 0.41 kg, providing a compact solution for marine corrosion protection.
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$ 33.74
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1-2 weeks delivery time Allpa magnesium sacrificial anodes with two recessed mounting holes for bolt-on marine installation. The range includes Allpa 9077970 measuring 150x60x25 mm with an 80 mm fixing centre distance and weighing 0.33 kg, 9077971 measuring 250x65x28 mm with a 140 mm fixing centre distance and weighing 1.05 kg, and 9077972 measuring 350x70x35 mm with a 200 mm fixing centre distance and weighing 1.50 kg.
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$ 33.53
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1-2 weeks delivery time Allpa magnesium sacrificial anodes with an elongated body and central longitudinal mounting slot for bolt-on marine installation. Allpa 9077975 measures 200x65x35 mm, while the larger 9077976 measures 320x65x35 mm and has a 160 mm fixing pitch.
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$ 47.24
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1-2 weeks delivery time Allpa 9077980 magnesium sacrificial anode with a conical body and central recessed mounting point for bolt-on installation. The anode has an outer diameter of Ø80 mm and weighs 0.26 kg, providing a compact solution for marine corrosion protection.
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$ 35.44
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1-2 weeks delivery time Allpa Type HZ zinc sacrificial hull anodes with integrated mounting strips for bolt installation, available in three sizes. Allpa 9077450 Type HZ-2 measures 165x30 mm and weighs 0.20 kg, 9077451 Type HZ-5 measures 165x40 mm and weighs 0.50 kg, while 9077452 Type HZ-10 measures 200x60 mm and weighs 1.00 kg. All versions are manufactured from zinc for marine hull corrosion protection.
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$ 11.72
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1-2 weeks delivery time Allpa zinc sacrificial anodes with two mounting holes for bolt-on installation, available in three sizes. Allpa 9077860 measures 150x60x25 mm with an 80 mm hole pitch and weighs 0.88 kg, 9077861 measures 250x65x28 mm with a 140 mm hole pitch and weighs 2.40 kg, while 9077862 measures 350x70x35 mm with a 200 mm hole pitch and weighs 6.00 kg.
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$ 33.06
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1-2 weeks delivery time Allpa zinc sacrificial anodes with an elongated body and central mounting slot for bolt-on installation. The range includes Allpa 9077865 measuring 200x65x35 mm and Allpa 9077866 with dimensions of 320x65x35x160 mm. Both versions are designed for marine installations where a slotted mounting arrangement is required.
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$ 58.05
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1-2 weeks delivery time Allpa 9077920 zinc sacrificial anode with a conical body and central recessed mounting point for bolt-on installation. The anode has an outer diameter of Ø80 mm and weighs 0.98 kg, providing a compact mounting solution for marine corrosion protection.
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$ 55.64
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1-2 weeks delivery time Navalloy 9017701A commercial hull disc anode for marine corrosion protection. The anode weighs 0.4 kg and has a height of 33 mm. Catalogue dimensions are Ø99 x Ø38 mm with a Ø14.3 mm mounting hole, providing a compact disc configuration for hull installation.
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$ 23.96
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1-2 weeks delivery time Navalloy HE Series European-style hull anodes with fixing straps, available in two sizes. Article 9017702A has catalogue dimensions of 140x100 x 34x16 mm with a 115 mm fixing centre distance, while 9017703A measures 160x118 x 45x25 mm with a 137 mm fixing centre distance. Both versions feature 6x12 mm mounting slots for installation.
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$ 11.99
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1-2 weeks delivery time Navalloy aluminium double disc sacrificial anodes designed for marine rudders and trim tabs. The range includes four sizes with diameters of Ø48, Ø72, Ø95 and Ø127 mm. Each model uses a two-disc configuration for installation on opposite sides of the protected rudder or trim tab component. Select the required version according to the anode diameter.
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$ 7.47
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1-2 weeks delivery time Allpa round aluminium sacrificial anodes designed for marine rudders and supplied as single disc anodes. The range includes Ø90 and Ø110 mm versions. Allpa 9077190 has a diameter of 90 mm and weighs 0.20 kg, while 9077191 is the larger Ø110 mm version.
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$ 27.59
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1-2 weeks delivery time Allpa round magnesium sacrificial anodes designed for marine rudders and supplied as single disc anodes. The range includes Ø70 and Ø90 mm versions: Allpa 9077960 measures Ø70 mm and weighs 95 g, while Allpa 9077961 measures Ø90 mm and weighs 110 g.
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$ 36
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How do Aluminum, Zinc, and Magnesium Anodes differ in protecting a boat?
Aluminum, zinc, and magnesium anodes all provide cathodic protection by acting as sacrificial metals, but their effectiveness depends on the water type and their electrochemical potential. Zinc anodes are traditionally used in saltwater and provide reliable protection in high-salinity environments. Aluminum anodes are more electrochemically active than zinc and offer a higher protective capacity for their weight, making them suitable for saltwater and brackish water and, with the correct alloy, many freshwater applications. Magnesium is the most active of the three materials and is primarily intended for freshwater, where its higher driving voltage provides effective protection in low-conductivity conditions. Magnesium anodes should generally not be used in saltwater or brackish water, as they may provide excessive protection and be consumed too rapidly.
Why is anode placement on the hull plate important for effective corrosion protection?
Correct anode placement is essential because sacrificial anodes must be electrically connected to the metal they protect and positioned where protective current can reach exposed underwater surfaces effectively. On metal hulls, anodes should be distributed around areas that are most susceptible to galvanic corrosion, including the hull plating, rudder, propeller shaft, stern gear, and other submerged metal components. Poorly positioned, undersized, or electrically isolated anodes may leave parts of the structure insufficiently protected. Proper distribution helps maintain a more uniform protective potential across the underwater metalwork and reduces the risk of localized corrosion.