Bay-Houston Towing Co. contracted with Orange Shipbuilding Co., Inc. of Orange, Texas to produce a second generation Robert Allan Ltd. designed Z-Tech tug. The design offers:
· The forward deck (over the skeg) has a low, flat sheer, creating a spacious, relatively flat and safe working deck, without any obstructive anchor chains, etc.
· For "sea-going" operations, the Z-Tech tug works astern in tractor mode, so the shape of this part of the hull is more rounded in plan than would typically be seen in an ASD design. There is no appreciable loss of speed in this direction of operation. The increased flare and freeboard at the "aft" end is simply to ensure a drier operation when towing in this direction.
· Only one winch is required for both harbor and coastal towing operations. When towing long distances, the Z-Tech will simply tow in tractor mode going "astern".
· The low sheer forward, coupled with the aft bias of the deckhouse and wheelhouse enable the Z-Tech design to work under large overhanging ship flares.
The vessel will be Orange Shipbuilding Hull H-391. The tugs will be 98.5 feet long, with a beam of 39.3 feet, a hull depth of 16.4 feet.
As in the first Z-Tech Bay-Houston Towing Co. ordered, the tugs will be powered by two of Caterpillar's new 3516C high power engines, delivering 3150 hp each. At 6300 hp, the tugs will be the most powerful docking tugs on the Texas coast. The vessel is designed to produce in excess of 75 metric tonnes of bollard pull. The Caterpillar engines are being furnished by Mustang Cat Power Systems, the authorized sales, parts, and service Caterpillar Dealer for the marine marketplace on the Texas Gulf Coast. Mustang Cat Power Systems is a sub-division of Mustang Machinery Company, Ltd. headquartered in Houston. The Caterpillar engines will be mated to Schottel drives, the Model SRP-1520 driving 106 inch (2,700 mm) stainless steel propellers. These drives are rated at a combined 6300 horsepower.
Markey Machinery Company Inc. will provide the bow winch, a Model #DYSF – 52 Escort Line Winch. The winch has an automatic render/recover mode and will be equipped with an application specific Markey tension meter. The winch will have a brake capacity of 500,000 pounds.
The tug will be built to FiFi1 standard, and will be equipped with two Caterpillar C18 engines powering twin fire pumps each rated at 5300 gallons per minute, with water mist capability built in.
All engines on the vessel, including main propulsion, fire pumps, and generators are EPA Tier II compliant.