Z-Tech® 4500 tugs ordered for U.S. Navy

November 8, 2007


Robert Allan Ltd. has been awarded a contract to design a Class of new Z-Tech® tugs for the United States Navy Pilots. To be designated as the Z-Tech® 4500 Class, these new tugs will be very similar in size to the current Z-Tech® 6000 Class tugs, of which more than twenty tugs have been built to date.

The tugs will be built in Tacoma, WA by J. M. Martinac Shipbuilding Ltd., who are a sub-contractor to Pacific Tugboat Services of Long Beach, CA, the prime contractor for the delivery of these new tugs.

The hull form for the new Z-Techs will be essentially identical to the well-proven and ocean-tested hull used on the recent ten-tug order for the Panama Canal Authority. Four of these tugs have now sailed across the Pacific under their own power, demonstrating that these tugs, designed essentially for harbour service are proving to be very capable sea boats.

The US Navy tugs will be based in Bremerton, Washington, and will perform ship-handling duties for the full range of US Navy surface warships 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 new tugs will have the following particulars, as illustrated in the accompanying preliminary Arrangement drawing:


Length Overall
Beam, Moulded
Depth, Moulded
Maximum Draft (overall)

Bollard Pull
Free Running Speed

– 27.42 metres (90′-0″)
– 11.65 metres (38′-3″)
– 5.00 metres (16′-5″)
– 4.88 metres (16′-0″)
– CAT 3512 C DI TTA Main engines
– Schottel model 1012 Z-Drives
– 2 x 1810 BHP at 1,600 rpm
– 40 Short tons minimum
– 12 knots minimum
– 7 days underway at 10 knots


The tugs are configured essentially as “day-boats” but also provide accommodation for a crew of up to six persons. 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 notoriously damp north-west climate, as well as provide a significant degree of noise attenuation in the crew spaces.

Construction of the first of this new series of tugs is expected to commence early in 2008.

For more information on these or any of the Z-Tech® family of high-performance tugs, contact us.