A vast variety of propulsion systems
Brunvoll offers an extensive range of CP-propellers, Reduction gearboxes, Thorque and CRP PM-systems, Azimuth Propulsion, Control, Alarm & Monitoring Systems.
Single point of contact
Brunvoll propulsion, manoeuvring and controls provide easier delivery, service and support.
In-house design and engineering ensure quality in project execution and integration of systems.
Brunvoll's integrated propulsion systems ensure time-saving installation, easy maintenance and simple service and support.
PRINCIPLE CP-PROPELLER SYSTEMS
Different pitch control systems delivered by Brunvoll. They all include CP-propellers, propeller shaft and gearbox with built-in clutch.
In an ACG system the servo motor system for the pitch control is placed inside the gearbox. The ACG system has a push-pull rod from the pitch mechanism in the hub through the propeller shaft to the servo motor piston located in the gearbox. Push-pull rod systems are typically recommended due to their simplicity and ease of access for service and maintenance.
In the EF system the servo motor system for the pitch control is located inside the propeller hub, and a radial OD-box is placed within the shaft line. The EF-system is ideal for propellers with long shafts. This system is also used for stand-alone delivery of a CP-propeller and propeller shaft.
In the EACG system the servo motor system for the pitch control is placed inside the propeller hub. The EACG system features a low pressure oil system controlled from an oil distribution system within the gearbox (or from a separated OD-box). The hub servo system is recommended when the length of a propeller shaft exceeds 20 meters, or in cases where propellers are highly loaded with large servo forces and medium/long shafts.
Brunvoll's CP-propeller configurations ranges from single-mode transmission systems to advanced systems customised for specialised vessels with a high number of operational modes.
Propulsion systems - Optimised to suit the actual vessel
The varying working conditions of a vessel require flexible solutions in order to execute all tasks efficiently. The goal is for the ship's propulsion system to be optimised to suit the ship's actual service profile. With different configurations of engines, gearboxes, propellers and tunnel thrusters, it is possible to achieve optimal flexibility, efficiency and economy.
Diesel Mechanical Propulsion
Simplistic systems suitable to all ship types with a narrow service profile. The system is driven by either a constant or a slightly varying engine rpm. Simultaneous running of an el-generator with fixed or floating frequency is possible by a Power Take Out unit (PTO).
Diesel Electric Propulsion
Flexible and efficient solution for a wide and varied range in propulsion power. The propeller is driven by one or more electric motors via the reduction gearbox. The power is delivered from the ship's electric supply system. The most efficient solution is achieved through variable rpm from one or more of the electric motors, to ensure that the propeller has optimised working conditions in the entire power range.
A hybrid system can be a simple and efficient solution designed for boost mode or take-me-home condition. The configuration enable ships with variable power rquirements to run at high propeller efficiency.
Complex Hybrid Propulsion
A hybrid system can be a complex configuration with numerous operational modes. The large number of operational modes enable the engines and propellers to run optimally over a wide power range. The hybrid propulsion system benefit from the best from two systems; the combination of electric propulsion and diesel drive. Installation of a battery pack would further enhance the flexibility in operational modes.
Direct driven CP-propeller in slow speed propulsion
The propeller is directly driven by a slow speed diesel engine, thus there is no need for a gearbox. The advantage of a CP-propeller is the rapid reversal of thrust direction, without need for a reversible engine. This system is an economical and reliable system for many merchant vessels.
Integrated Propulsion Packages
Brunvoll propulsion systems can be integrated with any medium speed diesel engines. Brunvoll has independent and non-exclusive supply agreements with major diesel engine manufacturers for easy contract handling of terms and conditions. With a proven track record and strong reference projects with major engine manufacturers, rest assured Brunvoll will provide an optimal integration of diesel engine and propulsion systems alike.
Optimised Propeller design for each vessel
Tailor-made blade design ensures optimum propeller efficiency with lowest possible vibration and noise levels.
Changeable propeller blade bearings in propeller hub
Brunvoll standard propeller systems are delivered with changeable bearings in propeller hub of high performance self-lubricating and wear restistant material.
Available for all ice class requirements
Brunvoll propellers can be designed to meet any class society notifications and up to the strongest arctic ice class.
Environmentally friendly systems
Brunvoll propeller systems can be delivered in compliance with the high industrial standards as US EPA VGP2013, DnV-GL Clean, DnV-GL Clean Design requirements.
Brunvoll CP-propellers are available in the following product range:
- Four-bladed propellers
- Hub diameter from 520 - 1900 mm
- Propeller diameter from approx 1600 - 8000 mm
- Power range from 500 - 20.000 kW
- CP-propellers with servo motor either in the gearbox, in the shaft line or in the propeller hub
- Blade design of high skew or normal skew
- Propellers are made of NiAl Bronze or stainless steel
A typical Brunvoll propulsion propeller package consists of:
- Propeller hub and blades
- Stern tube and stern tube seals
- Propeller shaft
- Shaft couplings
- Propeller nozzle
- Control system
- Temperature sensors, earthing device etc.
Design criteria of a Brunvoll CP-propeller
- The blade angle of CP-propellers varies from full ahead to full astern pitch.
- A CP-propeller offers a higher maximum bollard pull, as it is possible to optimise the relation between rpm, pitch and power.
- With variations in operating conditions, propeller performance is enhanced with a CP-propeller due to optimum pitch/advanced ratio.
- A CP-propeller increases flexibility if available engine power is reduced.
- For ducted propellers it is possible to demount propeller blade with propeller inside the nozzle.
- The propellers from hub size 68/4 and upwards are all normally delivered in stainless steel hub with changeable propeller blade bearing in hub. The bearings are made of high performance self-lubricating and wear resistant bearing material. This application increases the lifetime of the propellers with years of operation.
Optimised Brunvoll propeller systems
Brunvoll serves a large variety of vessel applications. There is a continious demand for propeller designs to be optimised in order to achieve the highest energy efficiency. All Brunvoll CP- and FP-propeller configurations are designed for the particular ship.
Propeller blade data such as diameter, pitch, rpm, skew and local distribution, are always carefully selected to give the best solution with respect to both efficiency and noise/vibration characteristics. Tailor-made blade design ensures optimum propeller efficiency with lowest possible vibration and noise levels.
have a push-pull rod from the pitch mechanism in the hub through the propeller shaft to the servo motor piston located either in the gearbox or in the shaft line. Push-pull rod systems are often recommended because of their simplicity and easy accessibility for maintenance inside the vessel.
have the servo piston located in the propeller hub. The low pressure oil system is controlled from the oil distribution system in the gearbox or from a separate OD-box. The hub servo system is recommended where the length of propeller shafts exceed 20 meters or in cases with highly loaded propellers with large servo forces in combination with moderate or long shafts.
is an option on standard CP-propeller systems.
On a feathering propeller the blade angle can be arranged in line with the water flow. This reduces the water resistance and gives the following advantages;
- power reduction by shutting down one of the two propellers in twin screw systems
- allows for maintenance at sea of one shaft line while the other is in operation
With twin screw installation and one side out of operation it is possible to reduce requirements for the shaft brake with CP-propeller.
Fixed Pitch (FP) Propellers
Brunvoll offers FP propellers in a complete propulsion package with ThorqueTM or gearbox including propeller design, propeller shaft, stern tube bearings, seals and nozzle when required. Brunvoll FP are always as mono-block or with adjustable bolted propellers for fine-tuning of the propeller and the possiblility to adjust and optimise the propeller during the vessel's lifecycle. The FP-propeller range follows the range of Brunvoll ThorqueTM and gearboxes.
Brunvoll utilizes state of the art hydrodynamic knowledge
Brunvoll's hydrodynamic expertise in propeller design is based on calculation methods of the latest hydrodynamic theories and tank test results.
Brunvoll has participated in international joint industry projects (JIP) to get first hand knowledge of test results from theoretic knowledge and through development of practical methods for accurate predictions of full scale performance.
The JIP-programs has been developing analytic methods and design- and analysis tools deeply rooted in ground breaking results from research projects where hundreds of CFD-calculations have been implemented in simulator software for evaluation of the performance of manoeuvring in propulsion systems.
These projects represent the state of the art in propulsion with global major propeller manufacturers and research institutes in Norway, The Netherlands, Germany and China participating with the same goal - to establish modern and accurate design and analysis tools, and to secure long term competence in key areas of this discipline.
Brunvoll is or has been participating in the following JIP's:
- Bollard Pull JIP, Marin Netherlands (2016-)
- Wageningen TT JIP Series (2015-2018)
- Full Scale Performance Prediction For Energy Efficient Ship Design (2013-2016)
- CD Propeller Series Phase I & II (2011-2016)
- Low Speed Manoeuvring Project (2009-2012)
- Norwegian Propeller Forum I & II (2004-2011)
Brunvoll Integrated Costa Propulsion
A twisted leading edge rudder with Costa bulb and a CP-propeller with hub cap acting as one system.
The solution is proven to increase propulsion efficiency, give better manoeuvrability and reduce pressure pulses.
It is a robust and simple construction with similar installation time as for conventional rudder and cp-propellers.
Propeller nozzle profiles
A ducted propeller gives up to 30% higher thrust at low speed compared to an open propeller.
Brunvoll is optimising the propulsion efficiency by applying the best nozzle profile to the vessel based on given service profile.
Brunvoll HE nozzle profile
is recommended for ships with high bollard pull requirements, and low propeller loading at higher speed. The Brunvoll HE nozzle also has a better astern performance than the 19A nozzle.
19A nozzle profile
is recommended for many installations since it has a good overall performance in different running conditions.
37 nozzle profile
is recommended for vessels with high priority to astern performance. The forward bollard pull will be at the same level as for the 19A nozzle, but at higher speeds the performance is not competitive compared to the 19A nozzle.
All Brunvoll gearboxes are customised for the specific vessel with the right number of operational modes and PTO/PTI functions.
GREAT ARRANGEMENT FLEXIBILITY
The wide range of gearbox models and PTO/PTI options gives the best possibility to find the right system solution.
CONTINUOUS PRODUCT DEVELOPMENT
Brunvoll's experience and close location to well-reputed marine clusters have given us first-hand knowledge of new development and strict requirements for demanding customers.
INTEGRATED PROPULSION SYSTEMS
The combination of Brunvoll propellers, gearboxes and control systems are suitable for all vessel types and all medium speed engine brands.
The in-house design and assembly of reduction gearboxes are based on years of experience, engineering skills and excellent workmanship, making them some of the most reliable gearboxes in the market.
HIGH QUALITY MATERIALS
All materials used in the gearboxes are carefully selected to ensure the right conditions of the product.
- The gear housing is made from high quality cast iron to achieve a rigid and stiff design to safely absorb all forces during operation at maximum load.
- Fluid film bearings for pinion and bull gear shafts ensure extremely good reliability.
- The gearwheels are of the highest quality and designed with large safety margins.
- Hydraulic operated multi-plate clutches for optimum and smooth operation of the entire propulsion system. Brunvoll Soft ClutchR on all main clutches improves lifetime for clutch and gearbox.
Gear type: Vertical Offset
Model range: ACG 450 – ACG 1400
Power Range: Approx 500 kW up to 20.000 kW
PTO/PTI: Options for flexible built-on PTO/PTI units
Gear type: Vertical Offset, K-type Compact design
Model range: ACG 600K - ACG 980K
Power range: Approx. 2.500 kW up to 7.000 kW
Depending on selected rpm and ice class notation
PTO/PTI: Integrated PTO
Gear type: Vertical Offset - 2-speed type
Model range: ACG 680 2sp - ACG 1080 2sp
Power range: Approx 2.200 kW up to 10.000 kW
Depending on selected rpm and ice class notation
PTO/PTI: Integrated PTO/PTI
Gear type: Horizontal Offset
Model range: ACG 450H - ACG 1400H
Power range: Approx. 500 kW - 20.000 kW
Depending on selected rpm and ice class notation
PTO/PTI: Options for flexible built-on PTO/PTI units
Gear type: Twin-in Single-out, Horizontal Offset
Model range: ACG TS 1000 - ACG TS 1700
Power range: Approx. 2 x 1.100 kW - 2 x 8.900 kW
Depending on selected rpm and ice class notation
PTO/PTI: Options for flexible built-on PTO/PTI units
2-speed gearbox systems
Optimised running conditions
Great advantages and flexibility with a 2-speed gearbox system giving optimised running conditions with huge fuel savings for your vessel.
Huge fuel saving for ships with considerable time in modes with low power to the main propeller.
Integrated propulsion systems
Brunvoll's 2-speed gearboxes can be configured in a Brunvoll propulsion system with propellers, tunnel thrusters and control systems, integrated with any medium speed engine.
High quality materials and design
Brunvoll 2-speed gearbox design is based on the same design principle as for all Brunvoll gearboxes, and benefit from long experience, engineering skills and excellent workmanship.
The gearboxes are designed in 3D and analysed for full load to ensure excellent performance in both normal and critical operations.
All materials are carefully selected to ensure the right conditions of the product.
2-speed gearbox range:
- ACG 525 2sp
- ACG 680 2sp
- ACG 750 2sp
- ACG 850 2sp
- ACG 980 2sp
- ACG 1080 2sp
The gearboxes are designed with an integrated PTO shaft for aft mounting of generator/electric motor. Power ranges from 1100 kW to 10000 kW.
The power range for each gearbox depends on selected rpm and ice class notification.
All 2-speed gearboxes are in vertical offset version.
Boasting flexibility and efficiency in a diesel-mechanical system with PTO
The 2-speed reduction gearbox is a fully integraged solution to provide the option for two steps of different propeller speed in a diesel mechanical configuration. The system is ideal for vessels with variations in power requirements, such as Purse Seiners, Trawlers, AHTS, Seismic vessels, Mega Yachts and Rescue vessels.
Diesel mechanical mode Step1 and Step2
The graphs of Step1 and Step2 in the diagram above show the direct effect of reducing the rpm using the 2-speed reduction gearbox. The configuration consists of a diesel mechanical engine and a generator in PTO-condition. By designing optimum power distribution to the propeller and utilising the remaining power to the PTO, there will be full utilisation of the available power from the main engines.
Diesel-Mechanical mode Step3
The 2-speed gearbox also offers possibility to run the diesel-engine at reduced rpm as a 3rd step, for further reduced fuel comsumption. The generator will still run at rated speed and power.
Optimised running conditions with a combined generator / electric motor
For vessels spending most of their operational time in low propulsion power condition below 40-50% of their total available power, there is a significant potential for power saving if the zero pitch loss can be reduced or eliminated. Brunvoll's solution to this issue is the 2-speed reduction gearbox, combined with diesel-electric features to create a very flexible and redundant hybrid configuration.
Boost mode for maximum power demand
For high propulsion power, the 2-speed reduction gearbox can combine main engine power with input power of the shaft generator acting as a motor, creating a Boost Mode. This mode benefits the size of the main engine which can be reduced while still maintaining the required maximum power needed for certain operations such as anchor handling, towing and trawling.
Variable rpm in diesel-electric mode
With reduced propeller rpm, the main engine can be shut down when running in diesel-electric mode. Alternatively, the electric motor can be driven by a frequency converter (VFD), in this way the rpm can be adjusted even lower allowing additional fuel savings.
Simulation: Seiner/Trawler saves up to 25% fuel in searching mode
Fuel analysis of the difference with a 2-speed gearbox versus a single speed gearbox in a typical operation profile of a combined seiner/trawler shows the vessel may save up to 25% fuel while in searching mode.
Simulation: AHTS saves up to 32% fuel in DP mode
Fuel analysis of the difference with a 2-speed gearbox versus a single speed gearbox in a typical operation profile of an anchor handler tug supply vessel, shows the vessel may save up to 32% fuel while in DP mode, and even more in a wait on position.
New gearbox solution featuring space-saving innovation
Brunvoll's Spindrift propulsion system represents an innovative space-saving philosophy. The flexibility and simplicity of Spindrift system give vessels more space to utilise by rearranging placement of the gearbox and the electric motor towards the rear of the hull.
The compact design of Spindrift gearbox offers easy installation, and the concept gives additional hull efficiency, propeller efficiency and buoyancy in the aft ship.
Brunvoll Spindrift concept is patent protected.
Significantly larger amount of space for cargo. Minimal installation in the storage room. Easy accomplishment of SPS codes for passenger transport.
Maximum efficiency by tilting the propellers into the direction of the waterflow. Improved hull efficiency with the added appendix.
Brunvoll design principles ensuring maximum strength and stiffness for excellent performance in normal as well as critical operation.
POWER TAKE OUT (PTO) & POWER TAKE IN (PTI)
Brunvoll has a wide range of different configurations for powering generators or pumps from the reduction gearbox. The PTOs can be primary or secondary driven, and most PTOs are available with multiple outputs. This applies to all gearbox configurations except for the K-version which has an integrated PTO-function with only one output. Brunvoll offers PTO versions with two different speed settings.
The PTOs are usually delivered without clutch. The PTO may be delivered with an integrated hydraulic clutch, which is relevant when running a pump or when a PTI function is wanted for "take me home" function, or as boost in addition to main engine power.
The PTOs have the following designations:
- PF: A primary driven PTO front mounted. This PTO operates independently of main clutch status.
- SA: A secondary driven PTO aft mounted. This PTO is always running when the propeller is running.
Single system with clutch + PTO type PF without clutch
This system contains a primary driven PTO without clutch, which is always running with the engine. The PTO can be used for generators or pumps.
System designation: ACG 62/600 PF525
Single system with clutch + PTO/PTI type PF with clutch
This system contains a primary driven PTO with engine release clutch. The PTO can run independently of the propeller. Usually used for generators or for PTO/PTI solutions where the generator also can operate as electric motor for boost or "take me home" function.
System designation: ACG 62/600 PF525-1c
Single system with clutch + PTO/PTI type SA without clutch
This system contains a secondary driven PTO for shaft generator, where the PTO always runs when the propeller is running. This system can also be used as PTI with electric motor for boost or "take me home" function.
System designation: ACG 62/600 SA525
ThorqueTM Propulsion System
A unique permanent magnet propulsion motor with integrated pitch and thrust mechanism for CPP applications
ThorqueTM is available in single screw and twin screw configurations
- High efficiency
- Compact design
- Reduced emissions
- Robust construction
- Low noise
ThorqueTM is also available in fixed pitch configurations.
ThorqueTM is patent protected.
ThorqueTM is the most efficient motor for converting electric power into propulsion power, either the power comes from a power storage or an electric power production unit.
ThorqueTM is ideal for vessels requiring a wide and varied range in propulsion power. The system keeps high efficiency in the entire speed range, and in the lower speed range ThorqueTM is superior to systems with gearbox and asynchronus electric motors.
ThorqueTM is a new concept in a combination of well-known and proven technologies carefully selected from the permanent magnet (PM) motor and gearbox industries.
Reliable conventional CP propeller and shaft line directly connected to the ThorqueTM with integrated thrust and pitch mechanisms - makes this a unique propulsion system.;
Each ThorqueTM is designed to meet the requirements of the specific vessel regarding power/rpm and class society regulations. ThorqueTM is normally designed for a lifetime of 30 years.
In vessels with electric power generated from diesel fuel oil, the efficiency of the ThorqueTM allows for reduced oil consumption and thereby reduced emissions to air.
ThorqueTM propulsion system meets requirements for Clean Design and Green Shipping
High power density
The high torque/power density in ThorqueTM allows for a compact configuration with great arrangement flexibility and better utilisation of the vessel. The high power density enables an immense reaction force and acceleration from zero rpm.
"Multi Green" of FSV Group is the first vessel in operation with a ThorqueTM and CP propulsion twin screw system.
"Stormur" is the first vessel in operation with a ThorqueTM Plus – single screw system.
ThorqueTM Compact Concept
- a complete configuration in hull appendix
ThorqueTM is available in a complete concept including
- ThorqueTM PM-motor
- Nozzle / rudder nozzle
- Steering gear
- Tunnel thrusters
- Control systems
- Power supply
- Hull appendix
- Interface to hull
The major benefits of ThorqueTM Compact Concept is:
- DP capability
- Fuel efficiency
- Course stability
- Easy installation
ThorqueTM Compact Concept is ideal for new building as well as retrofit.
Contra Rotating Propulsion
A complete propulsion system with significant efficiency improvements, low emissions and noise, and easy installation with low maintenance costs.
Great advancement in efficiencies in hull, propeller and motor makes the Brunvoll CRP-PM a unique system based on a combination of known technologies.
The high efficiency gives considerable fuel saving and reduced emissions of CO2, NOx and SOx.
Fixed pitch propellers and short shaftline directly connected to slow speed permanent magnet motors gives a system with easy installation and low maintenance cost.
Environmentally friendly systems
Better noise output with each propeller having a lighter load. Ultra quiet PM motors also make for a comfortable environment within the vessel.
More than 20% higher efficiency in transit mode
Based on calculations from model test simulations of Brunvoll CRP-PM system versus Azimuth CRP twin screw system.
Robust and protected
Fixed pitch propeller system with few movable parts.
The propeller is protected behind the center skeg far from the ship side, while the propeller tip is well above the baseline and further protected by a solepiece.
The Brunvoll CRP-PM system is a shaft-in-shaft propulsion system with two separate monoblock fixed pitch propellers. Each of the propellers are individually and directly connected to separate permanent magnet motors.
Quick response from the system gives excellent manoeuvrability. The difference in dynamic positioning capabilities between Azimuth twin screw propulsion and Brunvoll CRP-PM is minimal.
Red curve: Brunvoll CRP-PM: 1 CRP, 2 tunnel thrusters in aft ship, 2 tunnel thrusters and 1 retractable azimuth thruster in fore ship.
Green curve: Azimuth system: 2 azimuth propulsion thrusters in aft ship, 2 tunnel thrusters and 1 retractable azimuth thruster in fore ship.
Brunvoll Azimuth Propulsion Thrusters
The dedicated Brunvoll Azimuth Propulsion Thruster is based on our extensive in-house experience with design, production and servicing of Brunvoll Tunnel and Azimuth Thrusters since 1965.
The Brunvoll Range of Azimuth Propulsion Thrusters Includes both, cpp and fpp, whereas the cpp Azimuth Thruster is our main product.
The Azimuth Propulsion Thrusters are available as open pull and ducted push propellers.
Also available are Azimuth Propulsion Thrusters based on the RDT (Rim Driven Thruster) concept with PM technology.
L- and Z-drive, weld-in and trunk mounting
- Can be supplied with or without propeller nozzle
- Various designs of propeller blades and propeller nozzles are available to suit the bollard pull, speed requirements and positioning abilities of the vessel
- Controllable pitch or fixed pitch propellers are available
- Propeller shaft with multiple sealing systems and safety chamber
Top mounted electric motor provides direct power transmission via only one gear.
Right angle top gearbox for horizontal drive from diesel engine or electric motor is available:
- Top gearbox pressure lubricated, completely oil-filled at standstill
- Supplied complete with lubrication pump and monitoring
- External clutch can be supplied
A steel structure/trunk with a top plate/flange is provided for bolting into the hull via a well with a counter flange provided by the yard.
A steel structure/trunk is welded to the hull structure.
For both options the trunk shape and hight are tailored to each vessel.
The underwater unit (gear box and propeller) is mounted from below.
Push ducted thrusters
Azimuth Thrusters with propeller nozzle
Mostly applicable for vessels in the low to medium speed range with requirement for high pollard pull in towing or pushing operations, typically tugs and other vessels with req to towing capab and or. DP operations.
Pull open Thrusters
Azimuth Thrusters with open propeller
Applicable for vessels in low speed to medium high speed range with operations in transit and with requirement for efficient propulsion, for a wide range of various ship types
RDT Azimuth Propulsion Thrusters
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 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, 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.
Brunvoll RDT has no central shaft and no shaft supporting struts. This
improves propeller efficiency and reduces propeller induced noise and
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 RDT for main propulsion has a nozzle, which may be of the accelerating or decelerating type. This is an advantage when the thruster operates with a rudder angle since the duct will reduce the negative effect on noise and vibration due to an inclined inflow.
Greater efficiency means reduced emissions – a greener solution.
Simpler installation saves time and costs.