Cobalt Series Bulkhead Connector


Cobalt Series bulkhead connector for use with Cobalt Series Cable, Single-ended or Cobalt Series Cable, Double-ended (sold separately).  Rated to 600 m depth, includes M10 X 1.5 nut.  3-pin, 4-pin, 6-pin, and 8-pin versions available.

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The Cobalt Series of dry-mate underwater connectors and cables from Blue Trail Engineering sets a new standard for miniature waterproof connectors.  Cobalt connectors offer the same reliability as larger subsea connectors, but at a fraction of the cost.  With 316 stainless steel shells and PEEK inserts, they withstand long-term use in seawater at depths up to 600 meters.  In spite of their compact size, Cobalt connectors can handle high currents (up to 20 amps on the 4-conductor version).  Connector shells are keyed and feature a scoop-proof design, allowing them to be mated blind with no possibility of pin damage.


Cobalt Series cables feature a simple, robust seal between the cable jacket and connector shell that eliminates the need for overmolding. A second hermetic seal between the connector pins and the connector shell provides redundancy. Because Cobalt connectors do not require overmolding, they cost less than traditional molded cables and connectors and eliminate the danger of leakage due to cathodic delamination. A simple, proven O-ring seal between the male and female connectors makes Cobalt connectors both easier to use and more reliable than wet-mate connectors. Perfect for space-limited applications, Cobalt connectors take up a fraction of the volume of the industry-standard Micro-Circular connectors.


The Cobalt bulkhead connector fits in the same 10-mm hole as Blue Robotics penetrators, making quick-connect and quick-disconnect possible with Blue Robotics thrusters, tethers, enclosures, lights, grippers, and other accessories.  A Cable termination kit allows the user to retrofit an existing Blue Robotics thruster with a Cobalt connector.


The Cobalt bulkhead connector is available in 3-pin, 4-pin, 6-pin and 8-pin versions.  It can be installed in the wall of any enclosure, provided that the enclosure has a smooth outer surface to seal against the connector’s O ring.  COBALT BULKHEAD CONNECTOR MUST BE USED WITH COBALT CABLE (sold separately).

Additional information

Weight N/A
Dimensions N/A
Technical Details


Depth Rating

600 meters

Operating Temperature

0° C to +50° C


Maximum voltage

300 V

Rated current

3-conductor version: 12 amps

4-conductor version: 20 amps

6-conductor version: 5 amps

8-conductor version: 0.5 amps

Wire size

3-conductor version: 18 AWG

4-conductor version: 16 AWG

6-conductor version: 22 AWG

8-conductor version: 24 AWG

Wire stranding

3-conductor version: 19/30

4-conductor version: 19/29

6-conductor version: 19/34

8-conductor version: 7/32


Bulkhead connector shell

316 stainless steel

Bulkhead connector insert


Bulkhead connector pins


Cable connector shell

316 stainless steel

Cable connector insert


Cable sockets

tin-plated shell with gold-plated contact

Cable jacket

95A UV-stabilized polyurethane

wire insulation

3-, 4-, and 6-conductor versions: ETFE

8-conductor version: polyolefin

O ring


Locking sleeve



Bulkhead connector threads

M10 X 1.5

Bulkhead connector hex

16 mm

Locking sleeve threads

M16 X 1.5

Cable outer diameter

3 and 6-conductor versions: 6.4 mm

4- and 8-conductor versions: 8.0 mm