First Z-Tech® 7500 Class tugs from Robert Allan Ltd., for Suderman & Young Towing Company, L.P. of Houston, Texas

September 6, 2007


In July 2007, Thor, a new Z-Tech® 7500 Class tug, was delivered to its Owners, Suderman & Young Towing Company, L.P. of Houston, Texas. Thor is the first of this new class of powerful ship-handling/escort tugs developed by Robert Allan Ltd., Naval Architects of Vancouver, BC, and builds on the international success of its smaller cousin, the now well-known Z-Tech® 6000 Class, which since their introduction to the world market barely four years ago are now operating throughout South-East Asia, Australia, the Middle-East and in the Panama Canal. This delivery marks the first Z-Tech® tug of any class built in North America.

The Thor, and its soon to be delivered sister tug, classed for both harbour and coastal towing and tanker escort duty, will be used in the port of Houston.

The tugs were built to ABS Class notation ✠ A1 Towing Service, ✠ AMS, Escort, Fi-Fi 1″ by Main Iron Works of Houma, Louisiana. Another set of three tugs of the Z-Tech® 7500 class have recently been contracted with Orange Shipyards of Orange Texas, a division of Conrad Industries, Inc. for delivery in 2008 and 2009.


Particulars of the Z-Tech® 7500 Class tugs are as follows:


Length Overall
Beam, Moulded
Depth, Moulded
Draft, Maximum
Fuel Capacity
Potable water capacity
– 98′-8″ (30.00 metres)
– 39′-4″ (12.00 metres)
– 16′-5″ (5.00 metres)
– 17′ (5.18 metres)
– 169 cubic metres
– 24 cubic metres



Propulsion comprises a pair of CAT 3516B diesel engines, each rated 2,348 kW at 1,800 rpm, and each driving a Schottel model SRP 1520 Z-drive with a 2,700 mm diameter propeller through a hollow, in-line shafting system. This combination delivers a Bollard Pull of 75 tonnes ahead, 70+ tonnes astern, and provides a free running speed in excess of 13 knots.

The Z-Tech® 7500 Class tugs are outfitted for a crew of six persons, in modern and well-equipped facilities with a “down-home” touch to the decor provided by the shipyard.

The main hawser winch is a double drum, Model DYSF-52 hydraulic winch supplied by Markey Machinery of Seattle, WA. The winch has a line capacity of 750 feet (228 metres) of 10″ circumference (80 mm dia.) synthetic line, a brake capacity of 250 tonnes, and a line pull of 20,000 lbs. (9070 Kg) at a speed of 125 fpm (38 metres/minute) or 9,500 lbs. (4300 Kg) at 250 fpm (76 metres/minute).

Electrical power is provided by a pair of John Deere 6081AFM75 gen-sets, each rated 195 kW.

The tug has a full Fi-Fi 1 rating in accordance with Class notation requirements. The two fire pumps are driven by an independent fire pump engine.



The configuration of the “Thor” is shown on the accompanying General Arrangement drawing and photographs. Under the design guidance of senior Naval Architect and Project Manager Xuhui (Bill) Hu of Robert Allan Ltd., the Owner’s objectives have been fully satisfied with this handsome and powerful new tug.

For further information on this or any other high-performance Z-Tech® tug designs, please contact us.