The new Wide Operating Speed Range (WOSR) will be of particular interest to MJ readers, as Caterpillar has worked with Dutch dredging contractor Boskalis to develop a new type of performance capability for the 3500B series of engines specifically for use in dredgers, dredging equipment, tugs, fishing vessels and workboats.

WOSR allows customers much greater flexibility in how they operate their engines in order to deliver measurably better overall efficiency. The new WOSR performance is achieved by using a nominal 1,600rpm rated speed engine but allowing power to be maintained at a very high level out to 1,800rpm in the governor overrun curve. The end result is a flat-line constant power curve from approximately 1,200 to 1,800rpm.

WOSR is well suited for dredge pump drives and vessels such as ferries, harbour tugs and shallow water towboats that do a lot of manoeuvring or fishing vessels that would ordinarily use a controllable pitch propeller to accommodate the different operating requirements of hauling heavy nets or running in open water. The concept was proposed to Caterpillar by Dick Korf of Boskalis, the world's largest dredging contractor, which has hundreds of Caterpillar engines in its worldwide fleet. Mr Korf, a senior production and development engineer with Boskalis, was looking for a way to increase the productivity of the company's dredging equipment, in particular its mobile booster stations used to pump dredged material over substantial distances.

After discussing the specific technical needs of the dredging market, Caterpillar recognised that there would also be many other beneficial uses for WOSR and his since developed the solution for both Boskalis, which has purchased a number of Cat 3516B WOSR engines, and other customers as well.

Because the engine maintains a high power level out to 1,800rpm, the propeller is allowed to run at a much higher speed that should result in increased vessel speed in the free runing condition. Higher free running speed would be particularly useful for vessels such as tugs not running under tow, which would be able to increase speed for moving quickly between operations.

Cat 3512B and 3516B engines in the WOSR configuration are available for worldwide distribution immediately.

MJ Information No: 17531