Magnetic Retrieval Systems for Offshore Maintenance – Shapes, Sizes, and Applications

Working offshore means operating in one of the harshest environments on Earth. Equipment is often exposed to high winds, constant vibration, and the ever-present risk of tools or parts falling overboard. To minimize downtime and losses, magnetic retrieval systems based on neodymium magnets have become a valuable tool in offshore maintenance.

Why Magnets Are Essential in Retrieval

When tools, bolts, or small components are lost in the sea, recovery becomes difficult. Divers or ROVs (remotely operated vehicles) often rely on high-strength neodymium magnets to attract and lift ferromagnetic objects. Their compact size combined with extreme pulling force makes them indispensable.

Recommended Magnet Shapes for Retrieval

1. Disc Magnets
   • Best for: General recovery, attaching to flat surfaces.
   • Sizes: Ø 40–75 mm, thickness 10–20 mm.
   • Example: A Ø 60 × 15 mm N52 disc magnet can provide a pull force of over 100 kg.
2. Ring Magnets
   • Best for: Mounting with ropes or bolts for vertical retrieval.
   • Sizes: Outer diameter 50–100 mm, inner hole 8–12 mm.
   • Advantage: Easy to connect to carabiners or lifting equipment.
3. Pot Magnets (Encased Magnets)
   • Best for: Heavy-duty offshore recovery, resistant to mechanical stress.
   • Sizes: Ø 48–75 mm steel-cased neodymium pot magnets.
   • Advantage: Enhanced protection against chipping and corrosion.
4. Magnetic Hooks / Eyebolt Magnets
   • Best for: Direct rope connection in retrieval operations.
   • Sizes: Ø 60–80 mm with M8 or M10 threaded eye bolts.
   • Advantage: Designed specifically for magnetic fishing and retrieval.

Corrosion Protection – A Critical Factor

Offshore magnets are constantly exposed to saltwater. Standard neodymium magnets will corrode quickly without protection. Recommended coatings include:

• NiCuNi (Nickel-Copper-Nickel): Standard industrial coating.
• Epoxy: Strong resistance against saltwater exposure.
• Stainless Steel Housings: Encapsulation adds durability and prevents chipping.

For long-term reliability, fully sealed magnets are the best choice in marine retrieval systems.

Example Use Cases Offshore

• Recovering fallen bolts or tools during deck maintenance.
• ROV-assisted retrieval of small ferromagnetic components underwater.
• Securing equipment temporarily during inspection and welding tasks.

Conclusion

Magnetic retrieval systems are a cost-effective and efficient solution in offshore maintenance. The right magnet shape and size depends on the task:

• Disc magnets for general retrieval.
• Ring and eyebolt magnets for rope-based lifting.
• Pot magnets for heavy-duty and protected use.

With proper coatings and housings, neodymium magnets remain reliable even in the demanding conditions of offshore environments.