Silent Runner II Submarine Plan Features:

  • This two man submarine built around a surplus aircraft fuel tank.
  • Air is supplied by a standard SCUBA tank with a single hose regulator.
  • The propulsion units are two electric fishing motors.
  • Power is supplied buy four 12 volt deep cycle batteries.
  • The sub’s maximum running time on a full charge is about 5 hours.

The “Skipper” of the sub rides in a plastic air-bubble. His dive buddy (wearing full SCUBA gear) rides outside the bubble in a forward lookout position. Negative buoyancy is achieved by operating a variable buoyancy valve inside the subs cockpit. The motors can be tilted independently up or down to achieve thrust in the desired direction. Turns are accomplished by cutting the power to one motor or the other.

This sub has been operated by a number of people, including certified SCUBA divers, oceanographers as well as junior and senior high school students. All were impressed with its performance, handling and capabilities.

Though the construction of the sub is relatively simple it does require some considerable effort. Do not expect to build it over a weekend or two. All parts can be purchased from a hardware store, lumberyard and junkyard with the exception of the fishing motors.

Start with the surplus aircraft wing tank (any stripped-down tank with a 2-ft diameter will do). These tanks are quite readily available on eBay or at an aircraft “bone yard”. The cost of the tanks can vary quite a bit in price...So do careful shopping.

States vary in their regulations for registering a motor-driven boat. To be safe, check with you State Division of Marine Vehicles to learn if your sub must be registered.

The Silent Runner Sub has been featured in a number of publications such as Popular Mechanics, Skin Diver, Dive and Florida Magazines, and has been a tremendous hit with divers from all over.

Saga of Popular Mechanic’s Submarine
Built in Florida by Kent Markham (top photo) PM’s Two-Man Sub (cover story) traveled by Red Ball Van Lines to New York where it appeared on the David Frost Show during the summer. Shortly afterwards, PM donated the craft to Windward Oceanography Institute, Rowayton, CT where it was used to explore Long Island Sound.

About the Designer Kent Markham: Kent a teacher for many years in Jacksonville, FL stirred considerable interest in oceanography with the cooperation of the principal. This Silent Runner II was in fact, tested by several on the designer’s students.


  • Overall Length: 11’
  • Overall Width: 24” Sub Hull, 34” Including Motor Cover / Dive Planes
  • Overall Height: 5’
  • Power: 12 volts
  • Motors: (2) 36 lb. – 40 lb. Thrust
  • Running Time: Approximately 5 hours
  • Construction: Aluminum Wing Tank / Plywood / Fiberglass / Paint


  • (3) 17” x 24” Paper Drawings (Not a CD) Plans Include Details of:

    -- 3-View Drawings
    -- Full Feature Detailed 3d Drawing
    -- Waterproof Seals
    -- Motor Controls
    -- Hull Section Specifications
    -- Rib Details
    -- Battery Case
    -- Constant Buoyancy Valve
    -- Water Seal for Motor Lead in Wire
    -- Tank Cutting Specifications
    -- Acrylic Plastic Cockpit Dimensions

  • Construction Book with Photos
  • Plans will be shipped in 2-3 days after payment is received.
    Any type of SCUBA diving can be potentially dangerous. Other than Snorkeling only certified SCUBA divers should operate this sub and all standard diving procedures should be observed during a dive.

    -- NOTICE: No Refunds are Offered on Plan Purchases. --
    Web Content and Plans©
    Midwest Engineering & Design and Kent Markham

    -- Silent Runner Two Man Sub Plans to be Shipped Within the U.S.A. --
    $35.00 + $11.00 Shipping & Handling

    No International Shipping at This Time.

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