by Contributing Author

Brock Rosenthal, President, Ocean Innovations


Marshall Underwater Industries’ motto is Experience Builds a Better Product™ and founder Bruce Marshall has plenty of it. After serving a stint in the Navy, Bruce joined Santa Monica-based Electro Oceanics in 1966. EO, as it is commonly referred to, was the second company dedicated solely to the manufacture of underwater connectors. Starting out as a shipping and receiving clerk, Bruce worked his way up the company serving in a variety of positions including purchasing and sales, ultimately becoming the firm’s general manager.

During this period, EO went through several changes in ownership and management. Then in 1988 the company was sold and relocated to the East Coast. At the time, it was unclear what the future of the product line would be. Bruce decided that it was important to the user community to have continued access to EO style connectors and took it upon himself to make this happen. He chose to open at Moorland, Iowa because it was more economical in the Heartland than Orange County, California.

Experience Builds a Better Product

Marshall Underwater Industries (MUI)

MUI successfully re-created the EO connector line and in some instances made improvements. These connectors are molded out of neoprene rubber with a precise interference fit between the contacts and rubber to rubber interface to ensure waterproof integrity. A unique feature of the design is a vent hole in the female sockets that allow water to be expelled when the connectors are mated. The wiping action of the male pin ensures the electrical connections are made in a dry environment and permits the connectors to be mated or un-mated submerged in a de-energized condition, at practically any depth.

Please note the improvements:

  • The connector body length was lengthened for ease in handling.
  • Nickel Aluminum Bronze has replaced Brass, providing increased strength & corrosion resistance.
  • All right-angle bulkhead connectors are now O-Ring sealed rather than skirt sealed.
  • Additionally, locking sleeves are all the same length to avoid confusion over the correct connector/locking sleeve relationship.

Despite these advantages, MUI connectors are among the least expensive underwater connectors in the marketplace.

Over the years, Marshall’s connectors have been used in many interesting projects including on the Trieste II, in EPCOT Center, and in the submarine used in the James Bond movie, “For Your Eyes Only” to mention a few. Customers include the US and foreign navies, oceanographic research institutions, and many underwater equipment manufacturers.

After 47 years of making underwater connectors, and being at the helm of Marshall Underwater Industries since 1988, it’s safe to say that Bruce Marshall is living up to the motto, Experience Builds a Better Product.™