Like the rest of the shipping industry, tugboat and barge owners are facing increasing pressure to improve the environmental footprint of their fleets. One way to do so – while increasing fuel efficiencies and reductions in running costs – is to invest in new tugs that will use a hydro-mechanical propulsion system, claims Caterpillar Marine, which has entered into a collaboration agreement with Sanmar Shipyards to build such tugs.
The Marine Advanced Variable Drive (AVD) will use an innovative hydraulic propulsion system, the companies say. Caterpillar says that, unlike typical power take-in solutions, the AVD incorporates a planetary gear set allowing seamless clutch engagement of main engines, auxiliary engines, or both to provide a scalable power installation to meet operational needs in terms of maximum vessel speed, power, or bollard pull. This also allows propeller speed independent of engine speed for optimum engine efficiency – which results in 15% to 20% fuel savings, according to the companies.
“Thanks to the flexibility enabled by the innovative Caterpillar AVD technology, the speed of the vessel’s engines can be modulated and optimized independently from the speed of the fixed pitch propellers. The speed of the propellers can be varied continuously throughout their full speed range. In addition, the power of the main and auxiliary engines can be channeled independently or jointly to propel the vessel,” said Igor Strashny, Caterpillar Innovation & Technology Development Division engineering manager, with responsibility for AVD. Strashny says the technology is cost effective, and the fully integrated hybrid propulsion solution reduces maintenance costs and has conventional service requirements. He adds that it is scalable to meet requirements of a wide range of vessel types, applications, power levels and enables effective downsizing of engines without the loss of performance.
The vessel selected for the first Caterpillar AVD system will be a Robert Allan Ltd-designed RAmparts 2400SX tug.
Environmentally Responsible Tugs on the Rise
Announcements regarding “green” tugs were profuse in 2017, as operators and clients seek improved efficiencies, and as regulators demand improvements in environmental responsibility in the shipping industry, the Maritime Journal points out. For example, Wartsila added to its green innovations with three new tug designs, announced last November, featuring an HY propulsion system aimed at addressing environmental and efficiency issues.
Vendors Mentioned Above
- Caterpillar Marine
- Sanmar Shipyards