The following is text of a news release from Robert Allan Ltd. (RAL):
(VANCOUVER, British Columbia) — Robert Allan Ltd. has been awarded a contract to design a new version of the Z-Tech 4500 tug for the United States Navy (USN). The USN already has six vessels of this design, known as the YT 802 Class, in service. This first group was delivered between 2009-2012 and are in use in the Pacific Northwest and Japanese waters.
Four new tugs (with an option for two more) will be built in Anacortes, Wash., by Dakota Creek Industries. The hull form for the new vessels will be essentially identical to previous versions of this class of vessels, but with deckhouse changes to suit new EPA Tier 4 engines, which require significantly larger exhaust emission systems. Changes to the fendering system will incorporate feedback from operators on the existing vessels.
The U.S. Navy tugs will perform shiphandling duties for the full range of surface warships, 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. At least one of the new vessels will be assigned to an East Coast naval base which is the first use of this design with the Atlantic Fleet.
The new tugs will have the following particulars:
Length overall: 90′
Beam, molded: 38′ 3″
Depth, molded: 16′ 5″
Maximum draft (overall): 16′ 0″
Machinery: Caterpillar 3512E main engines and Schottel model 1012 z-drives
Power: (2) 1,810 bhp at 1,600 rpm
Bollard pull: 40 short tons minimum
Free running speed: 12 knots minimum
Endurance: Seven days underway at 10 knots
The tugs are configured essentially as day boats but also provide accommodation for a crew of up to six people. One of the unique features of the layout is the complete separation of 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.
These 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.
Construction of the first of this new series of tugs is expected to commence early in 2019.