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built in Louisiana. To date, ten 600- hp Z-drives (two per vessel) have been supplied, along with four 450- hp tunnel thrusters. Controls in- clude full follow up controls for the

Z-drives. The company is currently negotiating to supply thrusters for a second series of vessels, the specifi- (To the left): A technical diagram of the MJP Water

Jet J500S. cations of which call for 700-hp Z- drives with automatic hydraulic kick up of the outdrive leg.

Another company which supplies both thrusters and water jets is

North American Marine Jet, Inc.

The company builds two different types of marine jet propulsion sys- tems. Nomera 12-14-20 units cover gasoline or diesel engines from 140- to 800-hp and are designed for ves- (Continued on page 34)

A special Stator Screen is avail- able with the eight-inch system to keep debris out of the tunnel.

The thruster system, which fea- ture twin NiBrAl propellers, is avail- able in 25- to 50-hp models for boats in the 40- to 100-foot range, while boats in the 100- to 200-foot range can be accommodated using mul- tiple tunnels, the manufacturer claims. For corrosion protection, each Twin Prop unit is constructed using 316 L stainless steel housings and propeller shafts.

SchottelPump-Jets and propul- sion units have proven ideal for use in a variety of vessels. Recently, the Mare Azul of the Sines port authority in Portugal was equipped with two Schottel Pump-Jets, type

SPJ22. One pump-jet was installed in the bow and one in the stern. The

Schottel Pump-Jets reportedly give the Mare Azul exceptionally high maneuverability, while allowing the boat to operate in extremely shal- low water. Schottel propulsion units have also proven effective for use in a minesweeper and a research ves- sel.

The types of propulsion used in the vessels, SRP 300 E in the mine- sweeper and SRP 3030 LS in the research vessel, are new designs by

Schottel.

Schottel designed the SRP 300 E with the goal of minimizing noise emission. The actual generation of sound is reportedly minimized by using hypoid gear trains in the un- derwater gearbox.

Development of the SRP 3030 LS was prompted by the demand for a rudder propeller rated at 3,000 kW and optimized from the point of view of sound emission.

The use of high-performance materials such as GRP and polya- mide for the hydrodynamic optimi- zation of the underwater part of the unit, and the tractor-type propel- ler, all play a major role in reducing flow-induced noise generation.

KaMeWa offers an extensive product range, including thrusters, water jets (tunnel and rotatable) and controllable- and fixed-pitch propellers. The company designs and manufactures cp and fp propel- lers of all types from conventional propellers to highly-skewed propel- lers for low vibration/pressure pulse levels and quiet running. A techni- cal leader in the water jet field, the company has supplied water jet units rated as high as 27,880-bhp, and by the end of 1993, the aggre- gated power of KaMeWa's water jets amounted to 1.4 million bhp.

Thrustmaster of Texas, Inc. has found a hot market in supply- ing Z-drives and tunnel thrusters to the casino boats currently being

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