Schottel Unveil New Large Thrusters Units

By George Backwell at June 22, 2013 00:48
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Offshore vessels, tugboats and ferries all have a common need  –  to turn in their own length, even move sideways at times – and German propulsion specialist propulsion manufacturer, Schottel,  specialises in meeting that need.

'ESVAGT Aurora' (2x SRP 3030 CP): Photo courtesy of Schottel

A company whose corporate roots go way back to 1921 continues to lead through its ongoing investment in R&D, now unveiling a new generation of their larger thruster units with their housings hydro-dynamically optimised using CFD techniques.

These new thrusters well-known as SRP (Schottel Rudder Propellers) and STP (Schottel Twin Propellers) are available with a variety of reduction ratios to suit all common input speeds whether diesel engine or electric motor driven, and Schottel add that they are more compact in size than existing thrusters in the range.

Hydraulic clutch drives thruster hydraulic units
The new thrusters come with an independent, hydraulically operated multi-disc clutch, which not only engages and disengages the drive train from the thruster but also drives the hydraulic units of the thruster, making it practically self-contained.

The system is simplified to make maintenance easier, and the clutch is installed separately outside the gearbox using the same type of oil for operation and cooling that is used for lubrication of the thruster. No additional auxiliary units are needed to operate the clutch.

Hydraulic multi-disc brake
In addition to the hydraulically operated clutch, these units also have a hydraulically operated multi-disc holding brake, which is used to block the propeller from turning during service and maintenance work.

Like the clutch, the brake is a separate system outside the upper gearbox and is fully self-contained, requiring no mechanical interface or auxiliary units outside the thruster.

Slipping clutch controls propeller from zero to idle rpm
Schottel offers a new hydraulic slipping clutch to control propeller rpm from almost zero to idle speed which can be mounted on the upper gearbox instead of the standard clutch.

Contained in a separate housing, this clutch provides a power take-off for driving the hydraulic steering equipment. Thus the complete thruster is as self-contained as with the standard clutch.

In addition to the engaging and disengaging function of a standard clutch, the slipping clutch offers the possibility of controlling the propeller rpm from almost zero to the idle speed of the engine and is thus an ideal add-on for diesel direct-driven DP 2 vessels with fixed pitch propellers, double-ended ferries and tugboats using an engine with high idle speed.

Schottel say that all their thrusters are prepared for integration with their Condition Monitoring System S-COM as an aid to maintenance scheduling.

Comments (1) -

SRP appears to be suitable for Tug, AHTSV and other types of vessels where higher thrusts are required at lower speed. However, I am not so sure where (which type of vessels) STP application will be attractive. Of course, for shallow draft vessels due to reduced diameter propellers. Will it be comparable to propellers in pull position if it is considered for a PSV or an icebreaker, etc.

Further, is there any advantage with these propellers in terms of fuel efficiency? I could be rather naïve in asking this question.

Arun Dev |     6/30/2013 12:23:03 PM #

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