Triple screw lugger tug
Over in the USA, in the section of the Gulf Coast where the Mississippi meets the Gulf, shallow draft lugger tugs have been earning their keep suppling the near shore oil industry. But their size has been limited by their draft which is, of course subject to the prop size as much as the hull depth.
Over the years innovative tug designers and operators have found that three smaller engines, turning smaller props can deliver as much power with significantly less draft than a twin-prop boat with bigger engines. An additional advantage of the triple-screw arrangement is that, in the event of loss of power from one engine, the operator can still rely on two engines for maneuvering and safety.
Triple-screw shallow-draft boats come in a variety of forms including pushboats and model bow tugs. Although he builds vessels of those classes, Joseph Rodriguez of Rodrigues Shipbuilding is perhaps best known for his in-house designed Lugger-type tugs. Their aft mounted deckhouse provides a convenient foreward deck space for cargo. A single drum aft mounted towing winch allows towing or, with blocks, the boat can be rigged as a pusher.
Rodriguez recently delivered the Captain Nedo C. The vessel is a triple-engine lugger powered by three Cummins QSK19-M engines each producing 660 HP at 1800 RPM. The 70 by 29-foot tug has a moulded depth of 9.5 feet and is equipped with a M50 Pullmaster stern towing winch.
Even though the tug has a hefty 1,980 HP, when light loaded with fuel and water, she only draws 6.5 feet. Even with full capacities or 17,000 US gallons of fuel and 26,000 US gallons of water she is able to access most of the necessary sites along the shallow estuary of the Mississippi River.
By Jake Frith
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