How to Select an Underwater Connector: Depth, Contacts, Materials Checklist

Selecting the right subsea connector is a multi-dimensional engineering decision. A wrong choice -- undersized depth rating, incompatible material, wrong contact count -- can cause catastrophic system failure at depth. This guide walks through each selection parameter with practical guidance for ROV, AUV, offshore oil and gas, and oceanographic applications.

Step 1: Define Maximum Operating Depth

Depth rating is the primary filter for subsea connector selection. Apply a minimum 1.5x safety margin over your maximum expected operating depth:

Step 2: Determine Signal Type and Contact Count

Identify each electrical, optical, or fluid interface in your system:

• Power contacts: Determine voltage (AC or DC) and maximum continuous current. High-power connectors carry up to 150 A per contact. Allow 20% headroom on current rating.
• Signal contacts: Low-level sensor signals (0-10 V, 4-20 mA, RS-485). Standard signal contacts rated 3-10 A are appropriate.
• Ethernet: Use a dedicated subsea Ethernet connector (100BASE-TX or GigE rated) rather than wiring data signals through a standard multi-contact connector. Maintains 100-ohm differential impedance.
• Coaxial / RF: Sonar transducers, acoustic modems, and underwater cameras require 50-ohm or 75-ohm subsea coaxial connectors. Do not use multi-pin contacts for RF signals above 10 MHz.
• Fiber optic: High-bandwidth video, multiplexed telemetry, or command-critical links. Use a hybrid opto-electric connector or dedicated fiber optic connector.

Add all contacts, then select the standard contact count in the relevant series that is equal to or greater than your total. Reserve 15-20% of contacts as spares for future system expansion or in-field troubleshooting.

Step 3: Choose Shell Material

Step 4: Specify Cable Type and Termination

The connector backshell and cable entry must match your cable outside diameter (OD) and construction. Common considerations:

• Cable OD range: Confirm the connector's acceptable cable OD range (typically given as a min/max). Polyurethane jacket cables in subsea applications range from 5 mm to 25 mm OD.
• Jacket material: Polyurethane (PU) is preferred for subsea flex cables; avoid PVC in deep cold water (embrittlement below 5 deg C).
• Armoured cable: Cable armour must be terminated in the connector backshell, not passed through. Discuss with manufacturer if armour is present.
• Potting: Most subsea connectors require field potting of the rear (cable side) after termination. PU-based potting compound is standard; two-part epoxy for static, non-flexing terminations.

Step 5: Check Compatibility Requirements

If the connector must interface with existing equipment:

• Identify the existing connector brand and series (SubConn MCBH? SeaCon? Burton/Eaton?)
• Confirm whether you need a matching plug, matching receptacle, or both
• Request intermateability confirmation from the new connector manufacturer (RV Power Group can provide a written statement of intermateability)

Quick Specification Checklist

• Maximum operating depth: _______ m → select connector rated ≥ 1.5x this value
• Total contact count required: _______ → choose standard count that meets or exceeds
• Signal types: [ ] Power [ ] Signal [ ] Ethernet [ ] Coaxial/RF [ ] Fiber optic
• Shell material: [ ] 316L SS [ ] Titanium [ ] PEEK [ ] Delrin
• Cable OD: _______ mm
• Intermateability required with: [ ] SubConn [ ] SeaCon [ ] Burton [ ] None
• Quantity required: _______ (affects lead time and pricing)
• Any special requirements: [ ] High-temp seal [ ] Low magnetic [ ] Food-safe [ ] ATEX

Send your completed checklist to [email protected] and receive a full technical proposal within 48 hours.