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Nautican Triple Rudders are a system
of three narrow-bladed rudders that improve the manoeuverability of
vessels with nozzles. Joe
Gruzling, President of Nautican describes the typical problems of
rudders behind nozzles, “single rudders stall easily so the tug loses
thrust, and many multi-bladed rudders
choke off the water flow through the nozzle, especially during astern
operation.” The Nautican
Triple Rudders use a differential linkage, a unique geometry, and some
hydrodynamic tricks such as high aspect ratio foils and the cascade
effect, to “create higher lift forces with less drag on the rudder,”
according to Gruzling. The
result is a more efficient steering system that requires lower steering
torque than the equivalent single rudder.
In addition, the entire propeller outflow is directed up to 60
degrees to the side, without the loss of thrust or the engine
overloading usually caused by the flow being choked off.
For this installation Gruzling says that, “ we didn’t change
anything on the steering system. We
just cut the spade rudder off, leaving the rudder stock, then linked
that to our system.”
The Island Monarch
has just returned (November 2003) after retrieving the Island Trader from China and pushing
her across the Pacific to Vancouver.
Bob Shields, President of ITB
reports that all the skippers say the new Triple Rudders have
improved the tug’s manoeuverability. As an example, he recounts how,
“on the trip down the Wangpu River, where the [boat] traffic density
is high , like our roads in rush hour, and which like all rivers has
bends--and these are sharp bends--the pilot never had to order more than
10 degrees of rudder.” As
well, Shields says that the Triple Rudders, “had no problem keeping
the ATB up to weather on the ocean crossing.”
He sums up by saying the Nautican Triple Rudders,
“work just beautifully.”
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