Page 37: of Marine News Magazine (June 2021)

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Tech

File

A Mini-Tractor for the US Navy

By Alan Haig-Brown oduteh Marine, of Tacoma, Wash., has gained ? tted with s single Schottel SRP 150 azimuthing drive. recognition on meeting the stringent conditions The drive has a 41.3-inch propeller in a nozzle. The for- of military contracts. In 2020 they completed a ward-mounted drive is protected by a heavy pipe guard.

M contract to build a ? eet of ? ve small tugs. These A pair of ? ns, with approximately the same depth as the carry the military designation Work Boat Docking. single drive, enhance the maneuverability while providing tracking stability.

“The mission of the CNIC Work Boat Docking (WB The powerful heart of these remarkable craft is a single

Docking) is to provide waterborne support at U.S. Navy Cummins QSM11 engine, producing 450 horsepower at

Installations,” said Modutech’s Brian Swindahl. “The 2,100 rpm. This big power gives the little tug a speed over boats are required to have the ability to safely assist vessels 7.5 knots and a bollard-pull in excess of 10,000 pounds. including submarines for mooring and dry-docking, open This power allows the tug to operate in both push and and close security barriers, as well as to tow/push ? oating towing methods as required.

port operations support equipment. The boats must in- The steel hull carries an aluminum pilot house with clude propulsion equipment that is optimized for bollard heating and air conditioning. The wheelhouse can be re- pull, be highly maneuverable, and include suf? cient deck moved for repair or transportation. Similarly, a pair of push ? ttings and winches to tow astern, alongside, or push.” knees mounted forward are removable. Arching from the

In effect, the Navy wanted a Swiss Army knife that top of the push knees, over the house, and down to the aft would ? t in a mooring pocket. Modutech built a series deck, a cage allows the boat to pass easily under mooring of ? ve boats that do just that. The rectangular shaped 25- lines. Normal operation will be with a two-person crew, by 14-foot hulls have an 8-foot draft. The relatively deep although there is room for an additional ? ve passengers. draft results from the requirement that these little boats be The ? ve Cummins-powered Yard Tugs were deployed to highly maneuverable. To meet that requirement, they are naval yards in 2020.

Alan Haig-Brown www.marinelink.com MN 37|