Thruster Systems

• Enhanced gearbox for optimal hydrodynamic performance.
• Robust gear maintains optimum tooth contact in various operating conditions.
• More compact propeller hub.
• Replaceable blade bearing liners.
• Options for non-pollution seals and lip seal systems that can be replaced without removal of the propeller hub.
• Underwater unit can be removed with propeller blades in place.
• Pipe connections are easy to access.
• Pitch feedback unit includes a visible display.
• Shaft coupling enables easy installation and removal of drive motor.
• Reduced weight of the gearbox, propeller hub and tunnel – structural improvements ensure that the thruster is just as  rugged despite the lower weight.
• The tunnel is being optimized and strengthened to reduce vibration.
• Nodular cast iron in the motor frame improves stability, reducing vibration and noise.

No. 1 in LowNoise Thrusters

Thruster noise is a major problem for crews. The stress and discomfort it causes may threaten both performance and safety on board.

Quieter manoeuvring means better sleep, improving the alertness and efficiency of the crew.
Passengers enjoy a new degree of comfort.

Noise levels of 75-88 dB(A) are typical in cabins next to and above conventional tunnel thrusters. Brunvoll’s advanced technology can cut this by up to 15 dB(A). Combined with other measures, noise reductions of up to 20-25 dB(A) have been verified.

Brunvoll pioneered the LowNoise thruster in 1977. Today, Brunvoll is recognized world wide as the major supplier of effective LowNoise thruster solutions.

The Brunvoll RDT Concept with major potential in different areas

Brunvoll AS has since 2002 worked on the development and refining of Rim Driven Thruster Units.
The RDT is electrically driven with a permanent magnet (PM) motor.

Advantages with the RDT Concept

Permanent magnet technology provides greater flexibility in selection of motor speed (number of motor poles) and a motor with high efficiency running with a lower temperature.

The Brunvoll Rim Driven Thruster saves space and energy, offering higher propeller efficiency and lower environmental impact with exceptionally low noise. The RDT concept creates exciting potential for both manoeuvring and main propulsion.

The thruster, propeller and motor are in one compact unit – there is no need for an external motor, shafts or couplings.

With no gap between the propeller tips and the duct or tunnel, propeller efficiency is higher, while noise and vibration levels are exceptionally low.

The propeller blade thickness is optimized, and the radial thickness distribution as well as the radial load distribution is designed to enhance propeller efficiency.

The bearing design for the RDT eliminates the need of oil lubrication and there are no dynamic seals. Hence, the bearings (patents pending), are designed to minimise maintenance costs and eliminate any oil pollution.

The Brunvoll RDT has no central shaft and no shaft supporting struts. This improves propeller efficiency and reduces propeller induced noise and vibration.

The lack of a central shaft and shaft support stays, and the fact that there are no dynamic seals, is also beneficial with regard to damages due to line and rope entering the thruster.

The compact design increases arrangement flexibility and makes more space available on board.

The RDT can be fitted in places where there is little room for conventional thrusters.

Greater efficiency means reduced emissions – a greener solution.
Simpler installation saves time and costs.

The Brunvoll Retractable Azimuth Thrusters are used for dynamic positioning on offshore and research vessels, as mooring thrusters on shuttle tankers, and as stand by/take home propulsion on naval ships and coastal tankers.

Reliable and proven technology

• Almost an industry standard for shuttle tankers
• Shock-qualified thrusters available for naval vessels
• A popular choice for product tankers, reefers, chemical tankers and container ships in the merchant navy
• Can serve as an take-home propulsion

Various designs of propeller blades and propeller nozzles are available to suit the bollard pull and positioning abilities of the vessel

Controllable pitch or fixed pitch propellers are available

Propeller shaft with multiple sealing systems and safety chamber

In retracted position, the unit is mechanically locked using spring-loaded locking devices, allowing hull deflections without deterioration of the thruster alignment.

The bottom hull cover is landed and preloaded to the bottom structure of the ship by the spring-loaded locking devices.

The hull cover securely closes the bottom opening to reduce drag and protect the machinery against debris or slamming forces which could damage the unit.

Arrangement for vertically mounted electric drive motor is standard resulting in only one gear transmission.

Shaped as a column with a minimal footprint - the Retrctable Azimuth Unit is easily arranged and installed.

First-class inspection possibilities and easy maintenance of vital parts from in board the vessel.

Supreme tank top sealing system for the stem housing (submarine technology).

The integrated and robust guiding arrangement is designed to withstand operation in harsh environmental conditions.

The unit is lowered into operating position and retracted into the hull using hydraulic lifting equipment.

The unit can serve as "take home" / redundant propulsion.

As an option to vertically mounted electric motor, a right angle top gearbox for horizontal drive from diesel engine or electric motor is available, where;
– the top gearbox is pressure lubricated, completely oil-filled at standstill,
– and supplied complete with lubrication pump and monitoring,
– external clutch can be supplied

Brunvoll may deliver a complete plug-in installation with all of the necessary steelwork surrounding the Azimuth Thruster, fully assembled and pre-tested at our factory.

The illustration shows a complete shock qualified plug-in installation

When lowered, the thruster is locked and supported at keel level where it can act as a 360-degree azimuthing propulsion unit, ensuring that the vessel complies with DP Class II requirements, even with one main propeller.

When retracted it acts as a conventional tunnel thruster, locked in the upper position with a hull cover closing the opening in the keel.