US Navy Orders Four New Tugs
The U.S. Navy has ordered four new tugs from Anacortes, Wash. shipbuilder Dakota Creek Industries Inc., with options for two additional vessels. Construction of the series′ first vessel is expected to begin in early in 2019.
The vessels will be a new version of the Robert Allan Ltd. designed Z-Tech 4500 tugs. The Navy already has six vessels of this design, known as the YT 802 Class, in service. This first group were delivered between 2010-2012 and are in use in the Pacific Northwest and Japanese waters.
The new tugs will perform ship-handling duties for the full range of U.S. Navy surface ships, barges and submarines. For the latter duties the tugs are equipped with an extensive array of underwater fendering, as well as the typical fenders for surface ships.
The hull form for the new vessels will be essentially identical to previous versions of the YT 802 Class vessels, but with deckhouse changes to suit new EPA Tier IV engines, which require significantly larger exhaust emission systems, Robert Allan Ltd. said. Changes to the fendering system will incorporate feedback from operators on the existing vessels.
The tugs are configured essentially as day-boats but also provide accommodation for a crew of up to six persons. The layout completely separates the accommodation deckhouse from the machinery casing, a configuration designed to both provide a reasonably dry access to the accommodation spaces in the damp northwest climate, as well as provide a significant degree of noise attenuation in the crew spaces.
The tugs are equipped with a telescoping gangway, or brow, stowed across the aft end of the deckhouse. This is used to transfer personnel to other ships alongside or down to submarines.
The new tugs will have the following particulars, as illustrated in the accompanying preliminary arrangement drawing:
- Length Overall: 27.42 m
- Beam, Molded: 11.65 m
- Depth, Molded: 5 m
- Maximum Draft (overall): 4.88 m
- Machinery: CAT 3512E Main engines and Schottel model 340 Z-Drives
- Power: 2 x 1,810 BHP at 1,600 rpm
- Bollard Pull: 40 metric tons minimum
- Free Running Speed: 11.7 knots minimum
- Endurance: 7 days underway at 10 knots