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Propulsion evolution

Posted to Propulsion evolution (by on November 5, 2013

Naval architect focus on enhancing ship propulsion efficiency

As the shipping industry faces rapid and comprehensive changes in various sectors, naval architects find themselves facing the brunt of the heavy demands not just from the regulatory change being brought into place but also the increasing pressures to shore up engine efficiency, reduce pollution and above all the growing need to have ship designs which owners find cheaper and easier to operate.      

Taking the bull by the horns, the Institution of Naval Architects of India (INA) has created a forum under the banner ‘INAVATION Technical Meet’ to help members and other interests keep abreast of various developments and new technologies being developed. The recent INAVATION Technical Meet held last week - a quarterly event - brought into focus a fundamental issue that has gained significant importance, “Propulsion and Maneuvering - Vendors and Manufactures Forum”.

Featuring the “Developments on Wartsila 2S Generation X Engines and 2S low pressure DF engines” Sarad Sinha of Wartsila India explained that the company is committed to continuously improving efficiency because it means profitability for the customer and protection of the environment. “Fuel flexibility is an important matter as the customer has the option to decide on the type of fuels he can switch to,” he said. “Wärtsilä is passionate about optimizing lifecycle value by offering whatever its customers in the marine industry need from the most complete offering of marine products, integrated solutions and services”.

A synopsis of the marine engine design evolution over the last few decades focusing on the utility of higher stroke / bore ratio and increased propeller diameter formed the basis of the development. To the query “What is the market asking from us?” he explained, “Ships have specific design and engines have to adapt to the design. Normally engine price is 10% the cost of the ship and we are constantly looking to reduce this. The key requirements of the owners are reliability, total cost of ownership and serviceability, best ship performance and attractive overall cost. Earlier container ships had to operate at high speeds but now this has changed.”

Wärtsilä’s portfolio includes a range of products, solutions and services aimed at both land-based power plants and ship installations. As part of the portfolio, Wärtsilä offers catalysts (SCR) that reduce nitrogen oxide (NOx) emissions and scrubbers for removing sulfur oxides (SOx). They also offer complete oily water treatment systems for power plants and marine applications that meet the most stringent standards, as well as ballast water treatment (BWT) systems which are vital to prevent organisms from one ecosystem upsetting the ecological balance in another. Their range of offering cover total service packages, including start-ups, installations, engineering work, and maintenance and repairs.

Speaking on another aspect of the evolution that has taken place Jussi Kuusisto of Rolls Royce Marine India featured “Developments in Azimuth Propulsion Technology”. According to him there were several benefits of Azimuth Thrusters to convention propulsion. “They have superior maneuverability, provide direct trust and turning on the spot, improved crash stop, improved dynamic positioning capabilities; real redundancy in propulsion and steering.” He said that flexibility in design provides freedom in location and shafting, reduced building costs with compact package, simple hull form and short engine room. They can be installed late in the building process and service without dry-docking (if delivered as bolted-inversion).

Why use natural gas as a marine fuel? Kuusisto points out, “It is a simple, clean and efficient system. Single fuel – optimize; smoke free exhaust, inherently safe engine. Basically LNG is the tug fuel of the future.”

In his Keynote address by Prof R. P. Gokarn, world renowned authority on naval architecture and propeller design spoke on his favorite subject about improving propeller efficiency in ships. As ships have become larger, faster and more powerful and drafts of water levels have remained constant he presented various option available to designers in enhancing propeller efficiency. This include reducing energy loses, having higher diameter propeller and reducing the rpm (revolutions per minute), etc. He touched upon various theories and rules associated as well as operating conditions that affect efficiency.


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