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Conventional Tug - Nozzles - Coggle Diagram
Conventional Tug - Nozzles
Going Astern
Efficiency
Fixed Pitch
60% ahead thrust
CPP
40-45% ahead thrust
Nozzles
increase thrust
15-25%
towing / pushing
30%
zero speed
Increases water veloc
Small clearance propeller x nozzle
reduces tip vortex
High speeds
increase drag
Decreases steering capabilities
Might be steerable
Type 19A
Ahead Thrust
Type 37
BACKING Nozzle
little less efficiency going ahead
65% ahead trust fixed pitch
45% ahead thrust CPP
Hannan Ring Nozzle
19A
Slots cut after end
good Astern Thrust
70% fixed pitch special blades
60-65% fixed pitch ordinary blades
Nautical Nozzle (Lips HR)
Higher efficiency ahead
than 19A and 37
8-12% in BP
Astern
Better than 19A
Lower than 37
On AZYMUTH propulsion
Optima Nozzle
Optimum
Better ahead than 19A
Good astern as 37
Schottel's VarioDuct SDV45
Higher BP than 19A
Great medium / high speed efficiency
Good for shallow water
