Step 1 -- Define Your Operating Depth

Operating depth is the first and most critical selection parameter. Pressure at depth follows Boyle's law: every 10 m of seawater adds approximately 1 bar (14.5 psi) of hydrostatic pressure. Key depth breakpoints:

• 0-300 m: Shallow AUVs, coastal survey ROVs, diver-held instruments. Most commercial-grade IP68 connectors adequate.
• 300-1,000 m: Work-class ROVs, offshore inspection vehicles. Requires full wet-mateable design with dual O-ring per contact.
• 1,000-4,000 m: Deep-water construction ROVs, oceanographic moorings. Requires premium materials and factory pressure testing.
• 4,000-7,000 m: Full-ocean-depth instrumentation, hadal zone landers. Titanium or PEEK housings, extreme pressure testing required.

RV POWER GROUP standard micro circular connectors are rated to 7,000 m and pressure-tested to 600 psig -- covering the full commercial and scientific ROV operating envelope.

Step 2 -- IP68 vs. Wet-Mateable: Understanding the Difference

Both terms indicate submersion capability, but they serve different use cases:

• IP68 (IEC 60529): Continuous submersion beyond 1 m. Tested at a fixed depth per manufacturer specification. The connector may not be designed to connect/disconnect underwater -- it seals only when fully mated.
• Wet-mateable: Specifically engineered to be connected and disconnected while submerged. Uses spring-loaded contacts, O-ring face seals, or water-displacement designs to prevent galvanic corrosion and short-circuit during mating.

For ROV tooling, manipulator-assisted connections, and any application requiring in-situ reconnection, wet-mateable connectors are mandatory. RV POWER GROUP MCBH/MCIL series are wet-mateable by design.

Step 3 -- Contact Count and Signal Type

Count every signal, power, and ground wire in your application separately:

• 1-4 contacts: Simple sensors, single-axis thrusters, LED lighting
• 5-8 contacts: Multi-axis thruster control, RS-232/RS-485 + power
• 10-14 contacts: Camera systems with pan/tilt + video + power
• 16-19 contacts: Multi-function instrument packages, hybrid power/data

For mixed signal and power in the same connector, specify the current per contact to verify that contact and wire sizing are adequate. RV POWER GROUP offers up to 10 A per contact in the micro circular series and higher current ratings in the subsea 55 and High-Power series.

Step 4 -- Shell Material Selection

Step 5 -- Sealing Design

The two dominant sealing approaches:

• Dual O-ring per contact: Each individual contact pin or socket is sealed by two O-rings in series. Failure of one O-ring does not compromise the circuit. This is the approach used in RV POWER GROUP MCBH/MCIL series.
• Face seal with potting: A single moulded rubber face seal mates against the opposing connector face. Used in bulkier, higher-pin-count designs. Less tolerant of slight misalignment.

For safety-critical systems, dual O-ring per contact provides superior reliability and easier field diagnosis (individual circuit testing possible without full system disassembly).

Step 6 -- Environmental and Biological Fouling Resistance

Long-term subsea deployments face biofouling from barnacles, mussels, and microbial films. Key considerations:

• Titanium and PEEK resist fouling adhesion better than aluminium
• Spring-loaded sliding contacts sweep debris during mating
• Dummy caps (MCDC series) protect unmated bulkheads from settlement
• Annual inspection and O-ring replacement recommended for deployments exceeding 6 months

Connector Selection Summary Checklist

1. Operating depth (m): ___
2. Wet-mateable required? Yes / No
3. Number of contacts: ___
4. Maximum current per contact (A): ___
5. Signal types (power / RS-232 / RS-485 / video / fibre / Ethernet): ___
6. Shell material preference (Al / Ti / SS / PEEK): ___
7. Compatible with existing connector standard? (SubConn / SeaCon / Burton / other): ___
8. Deployment duration and maintenance frequency: ___

Send this checklist to [email protected] for a connector recommendation within one business day.