Tecnoseal USA Egg Type Shaft Anode - Magnesium

Tecnoseal USA Series Magnesium Egg-Type Propeller Shaft Anodes provide sacrificial cathodic protection for exposed marine propeller shafts in 19mm to 50.8mm sizes. Each USA egg-type anode is a two-piece magnesium casting designed to clamp directly around a shaft with the same nominal diameter.

What Is This Shaft Anode Used For?

The anode is fitted around an exposed propeller shaft and connected electrically through direct metal-to-metal contact. It is designed to corrode in preference to the shaft and other electrically connected underwater metals, helping to reduce galvanic corrosion while the anode remains active.

Key Features

• Brand: Tecnoseal
• Product category: USA egg-type marine propeller-shaft anode
• Anode alloy: Magnesium
• Typical water-selection guide: Fresh water
• Shaft-size range: 19mm to 50.8mm
• Mounting method: Split, bolted clamp
• Application: Exposed propeller shafts and electrically connected underwater metals
• Manufacture: Made in Italy by Tecnoseal

These magnesium variants are intended primarily for fresh-water operation. They share USA-series geometry, which is not interchangeable by appearance alone with Tecnoseal’s standard egg-type range.

How Do I Select the Correct Size?

Measure the shaft outside diameter with callipers and select the part number with an identical internal diameter. Do not choose by the anode’s outside diameter or weight alone. Imperial-labelled shafts should be checked by measurement because nominal inch and metric sizes can be close but are not always interchangeable.

• 00500USAMG: 19mm / 3/4in
• 00501USAMG: 22mm / 7/8in
• 00502USAMG: 25mm
• 00503USAMG: 25.4mm / 1in
• 00505USAMG: 28.6mm / 1 1/8in
• 00506USAMG: 30mm
• 00507USAMG: 31.8mm / 1 1/4in
• 00509USAMG: 35mm / 1 3/8in
• 00510USAMG: 38.1mm / 1 1/2in
• 00511USAMG: 40mm
• 00511MUSAMG: 44.5mm / 1 3/4in
• 00512USAMG: 45mm
• 00513USAMG: 50mm
• 00514USAMG: 50.8mm / 2in

Which Anode Alloy Should I Choose?

• Magnesium: generally selected for fresh water; it is normally unsuitable for prolonged salt-water use because it can be consumed too quickly.

Use the alloy specified by the vessel, drive or equipment manufacturer and keep the choice consistent with the existing cathodic-protection system. Water salinity, connected metals and stray-current conditions can change the correct selection.

Installation and Maintenance

Expose and clean the shaft to bright, bare metal where the anode will sit. Fit both halves squarely around the shaft and tighten the fasteners evenly in stages so the anode seats securely without rocking. Do not apply paint, grease or sealant between the anode and shaft, because direct electrical contact is required.

Inspect the anode at routine service intervals and after extended operation in a different water type. Replace it when materially consumed, cracked, loose or no longer able to clamp securely. Investigate unusually rapid or uneven wastage rather than simply fitting a larger anode.

Alloy Standards and Manufacture

Tecnoseal sacrificial anodes are manufactured in Grosseto, Tuscany. Alloy batches are checked using spectrometric analysis and produced to the applicable current US-MIL alloy specifications used by Tecnoseal for zinc, aluminium and magnesium marine anodes.

Frequently Asked Questions

• Can I fit a larger bore and tighten it down? No. The internal diameter must match the shaft so the anode seats correctly and maintains reliable electrical contact.
• Can the anode be painted? No. Paint or coating will isolate the sacrificial alloy from the water and can prevent the anode from working correctly.
• Does this replace every other anode on the boat? No. It protects only the metals electrically connected to it; retain the complete anode arrangement specified for the vessel.

Specifications