Bay Transportation Exercises Option To Build 3 More Ttogs
Aquamaster-Rauma, Wtirtsilti To Power Nabrico-Built Vessels Bay Transportation/Philip Towing of Tampa, Fla. has exercised options to build three additional stern-drive tractor tugs at an estimated cost of $18 million with Nashville Bridge Company (Nabrico) of Nashville, Tenn. The 110-ft.
(33.5-m)Kinsman Hawk is due to be delivered by Nabrico in November, 1994. The tugs are to be used for tanker escort service/ship assist and ocean-towing.
Aquamaster-Rauma Inc. will provide six 3001 Z-drive units to be installed in the three multipurpose stern-drive tugs. According to Aquamaster-Rauma vice president and vessel designer Gregory E. Castleman, each of the units is capable of absorbing 3,300 hp, resulting in total power of 6,600 hp for each vessel.
Bay Transportation reported that the ease of maintenance and time intervals between overhauls of the Vasa 32 engines over 10 years of field application were major factors influencing its engine choice, as well as the engines' extremely low level of NO emissions. Also considered was the high level of post-delivery technical support and parts availability that Wartsila was able to supply.
The hull design provides a clean flow of water to the thrusters, which enables them to rotate 360 degrees without encountering interference from vessels alongside.
Not only is the hull designed for speed running, but the bow is also shaped to provide high dynamic drag when the tug is in the various escort modes. Additionally, the thrusters are installed far enough apart for them to work in the transverse mode, which has been found to be very effective in escort service.
In the Kinsman Hawk class vessel, the Aquamaster 3001 Z-drive units will produce an estimated bollard pull in the 170,000-lb. range — making them, according to Aquamaster, the most powerful Z-drive tugs of their size in the world.
The running speed will be in the 14.5-knot range.
Aquamaster-Rauma has systematically researched tanker escort operation techniques and tug technology, verifying theories with model and full scale trials. This process has validated the use of two novel operating modes: • The "Transverse Arrest" mode utilizes the active thruster forces for retarding the tanker's forward advance without inducing a turning force and is designed to pose no risk of engine overload at any ship's speed. • The "Combination Arrest" mode combines the lateral lift and resistance of the tug's hull with the active thrust generated by the Aquamaster propulsors.
Bay Transportation's powerful stern drive tugs will add these two new operating modes to the traditional escort "indirect" and "direct" methodology to provide for safe tug and tanker escort operations. All four escort operating modes can be accomplished only with independently steerable Z-drives having nozzle propellers. The twin US3001 propulsion units have all of the reliable features associated with Aquamaster propulsion: • The strength of the units derived from the design philosophy for heavy duty ice conditions is designed for the most severe operating scenarios.
• The Aquamaster Z-drives can be installed and removed without docking the tug.
• The compact, self-contained archi architecture of Aquamaster units is designed for easy Z-drive installation and maintenance. • The standard Aquapilot drive control system, reinforced with the Micropilot single point joystick controller, provides redundant safety operations even a blackout of electric power on board will not jeopardize control of these tugs. The Aquapilot and Micropilot control systems are type-approved by the major classification societies, as well as by other regulatory bodies.
