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Propeller shaft arrangement

Propeller Shaft - Ruime keuze uit topmerke

Marine Propeller Shaft - Design And Constructio

The propeller shaft or tail shaft is supported by a bearing arrangement which acts as an intermediate phase between the sea and the ship Design of Propeller Shaft (dp) Since the propeller shaft is subjected to both bending moment due to propeller weight and twisting moment diameter of propeller shaft dp = 25% extra then the designed by pure torsion. dp = 1.25 x 400.135 dp = 500 mm Design of Intermediate Shaft (d) The intermediate shaft is subjected to bendin The propeller, shaft and gearing all represent dead weight that is duplicated with multi-shaft arrangements. In addition, the curve of engine output power as compared to size and weight is not linear; two smaller engines together weigh substantially more than a single larger unit of the same output One of the most common layouts for larger Tankers, Bulkers, Container and vehicle carriers is a layout with one or two cross-head main engines with direct drive with a fixed propeller. The main engine is directly connected with the propeller and the speed of the engine (90-105 rpm) is also the speed of the propeller

PROPELLER SHAFTING Stern tube contains bearing in which propeller shaft rotates.Aft bearing is the water tight seal which protect inner part and oil from sea water.Front side of bearing is welded to aft peak bulkhead and aft part is to propeller post.Normally water or oil is used as lubricating agent between shaft and shafting The propeller shaft bearing housings (stern bushes) can be installed either by press-fitting to machined bores in the stern structure or can be fixed to the stern structure by resin chocking Construction of propeller shaft. Propeller shaft or Cardan shaft is a mechanical component of transmission for transmitting torque and rotation. Propeller shaft consist of one or several cardan shafts or cardan hinges. It usually used to connect other components of a drive train that cannot be connected directly because of distance between them

Stern Tube and Shafting ArrangementsCCS to issue the survey guidelines for use of EAL as

Propeller Shaft Installation & Arrangement Clever Marine

Propeller Shaft Earthing Systems On sea-going vessels and ships, the propeller blades and propeller shaft bearings are vulnerable to spark erosion as the turning propeller shaft becomes electrically insulated from the hull. This is even the case on vessels that are equiped with sacrificial anode systems The propeller shaft arrangement which connects a transmission with a differential gear of a vehicle includes a first propeller shaft segment connected to the transmission at one end thereof and a second propeller shaft segment connected to the differential gear at one end thereof. The first and second propeller shaft segments are made of aluminum Gap and sag alignment is basically carried out to Locate pedestal bearings, Engines (for directly coupled engines), gearbox, etc with respect to the tail shaft (Propeller shaft) forward end. Once these are located, shafts are coupled either using hydraulic couplings or with flanged joints with spigots and fit bolts Propeller shaft lines connecting the engine to the propeller must be supported at points along its length and the whole arrangement must be designed to absorb and compensate for the various forces that will be acting upon it, the ship's structure and the engine or gearbox

The propeller shaft arrangement which connects a transmission with a differential gear of a vehicle includes a first propeller shaft segment connected to the transmission at one end thereof and a.. The main functions of propeller shaft that if transmits rotary motion and power to the differential. Propeller shaft consisting by three parts, i.e. hollow shaft, universal joints and slip joints. Fig: 2(a) Propeller Shaft. The propeller shaft may be hollow or solid as per design. In the case of cars and pick-up van Fig: Propeller shaft arrangement Where the thrust shaft is an integral part of the engine, the casing is usually fabricated in a similar manner to the engine bedplate to which it is bolted. Pressurised lubrication from the engine lubricating oil syste For such arrangements a short propeller shaft is used to drive each wheel. The engine and the transmission unit are attached to the vehicle frame with some flexible mounting. The rear axle housing with differential and wheels are attached to the vehicle frame by suspension springs

Propeller Shaft: Diagram, Parts, Types, Functions [PDF

A stern tube, which is present at the bottommost part of the ship, connects the engine, inside of the ship to the propeller outside.A propeller shaft passes through this stern-tube and is used to connect the propeller to the engine. Stern tube bearings, generally oil lubrication glands, are used to prevent the ingress of sea water inside the engine room and also to support the weight of the. Principle of Propeller Shaft Alignment. Download. MYKLASSHIP.COM is a Knowledge Management (KM) Consulting based maritime service provider being established among experienced and skilled professionals in the naval, maritime and offshore-related services for more than 50years, having a vision and mission to embark on providing specialized naval. Propeller shaft & universal joint. 1. Ch-4 Propeller Shaft & Universal Joint By, Deep Shah Sub: ATM (3330202) 2. Introduction of Propeller Shaft Propeller shaft is connecting the drive from gear box to final drive. Hence it is also called Drive Shaft. OR It is the group of parts connecting the transmission with the drive wheels Problems and failures in shaft line arrangement. Post date April 12, 2018 Post categories In Power, A typical propeller shaft system comprises the shaft itself attached to the propeller and passing through the stern tube plus intermediate shafts and coupling bolts, supporting intermediate bearings, the stern tube seals and a lubrication. An arrangement for transferring power of an engine to front and rear propellers of a ship comprises an inner propeller shaft directly coupled to the engine, an outer propeller shaft coupled to the..

Propeller shaft is a shaft which transfer the power developed in the engine to the wheels with the help of gear box. It consists of universal joints which allows the propeller shaft to move linearly when the wheels of the vehicle run over an uneve.. A propeller shaft bearing arrangement, which arrangement includes a plain bearing, which is lubricated with oil or water and which supports the propeller shaft extending through an opening in the body of a hull, and packing members for keeping the lubricant in the lubrication space and for preventing water from entering the bearing arrangement. A.F. Theriault & Son boatyard offers complete marine propeller repair and maintenance services A propeller in an inclined shaft arrangement has been simulated using a Reynolds-Averaged Navier-Stokes solver. The commercially available codes Ansys' Fluent and IcemCFD were used for the numerical simulation. The method has been demonstrated through a series of simulations advancing in complexity

A few pictures of the propeller shaft arrangement. The first 3 pictures show the outside. The whole shaft arrangement is slightly out of line with respect to the longitudinal axis of the boat. This enables pulling the shaft from the outside. Otherwise the rudder skeg would be in the way. The bracket holds the Vesconit The following is the driveshaft arrangement for a typical front-motor back wheel drive vehicle (a few autos have the transmission at the back). The propeller Shaft is the pole that transmits control from the gearbox to the differential rigging in an engine vehicle from the motor to the propeller in a vessel or flying machine. The propeller. In some arrangements two or three propeller shafts are used to make up the length. In some vehicles, the engine is kept at the front and the front wheels of the vehicle are being driven. In some other vehicles, the engine is at the rear and the rear wheels are being driven. For such arrangements a short propeller shaft is used to drive each wheel A propeller shaft earthing system will prevent early maintenance costs of the ships propeller and shaft bearings. On sea-going vessels and ships, the propeller blades and propeller shaft bearings are vulnerable to spark erosion as the turning propeller shaft becomes electrically insulated from the hull To properly choose a propeller we must first understand some of the basic nomenclature used to describe propeller geometry. Figure 1 is taken from Gilmer and Johnson, Introduction to Naval Architecture. Basic Nomenclature: Hub The hub of a propeller is the solid center disk that mates with the propeller shaft and to which the blades are attached

From the Midsummer 1911 magazine The Shipbuilder they describe the shafting arrangement of the Olympic/Titanic ships. For one thing, these ships were triple screw ships, not quadruple. Meaning they had two outside shafts, port and starboard, from the two reciprocating engines, and a single central shaft from the low-pressure turbine engine Sterntube assembly is to accommodate the propeller shaft arrangement on the vessel hull. It contains Sterntube along with bush housing, stuffing box, gland and Cutlass rubber bearings. Sterntube is supplied in M.S., S.S. or Brass. Other items are in Manganese Bronze or Gunmetal castings The Propeller Shaft itself showed clear signs of chafing. Therefore it was decided to send the complete Propeller Shaft arrangement as well as IPP coupling to Manufacturers WARTSILA for. A propeller shaft transmits engine torque to the rear wheels and therefore needs to be strong and reliable. Hitachi Automotive Systems Americas, Inc. developed two types of propeller shafts using alternative materials: Carbon Fiber Reinforced Plastic (CFRP) Propeller Shaft & Aluminum Propeller Shaft. They are part of Drive Train products line, through which passes the tube shaft or aftermost section of the propeller-shaft. Sterntube is the housing of the shaft bearings, generally two (one aft and one fore), that sustain the shaft and allows its rotation with less frictional resistance. The stern tube also accommodates the shaft sealing arrangement

Ship or vessel PHOENIX GAIA want to buy spare parts of Propulsion System And Rudder System Propeller Shaft and Arrangement on ShipParts.com, log in to view the detailed manufacturer, model and serial number information, and make a quotation to the buyer The paper explores the key advantages and disadvantages of both arrangements, arguing the case for the conventional propeller shaft configuration due to its lower capital expenditure, reduced.

Shaft Seals. Shaft seals are essential to the reliability and environmental compliance of a vessels primary shafting. They sit either on the forward end or both the aft and forward ends of a Stern tube on the conventional shafting of a vessel. They can also be found on Thruster or podded type propulsion units The stern tube of a ship has a peculiar shape and arrangement for carrying the propeller shaft. As the shape of the ship is streamlined at the aft end, there is very little space to accommodate the propeller shaft arrangement. The stern tube is situated at the aft peak of the ship's hull and the propeller shaft arrangement is also situated at.

•Output shaft with flange arrangement for propeller shaft coupling •All bearings of roller type with low friction losses and long lifetime •Spherical roller thrust bearing with low friction losses and long lifetime •All parts are made of the most suitable material qualities Simple one-piece propeller shaft with one slip-joint and two universal joints. 2.5 Divided Propeller Shafts and Their Support. Two-piece drive-lines, with two shafts and an intermediate support bearing are generally used on trucks with wheel bases from 3.4 to 4.8 m, but there is some overlap depending on the vehicle's work role Three tubular propeller turbine configurations are vertical shaft, pit, and S-type. They are appropriate for heads of 5 meters or less with a syphon type arrangement. Tube propeller turbine arrangements (Reference: books.google.nl) Pit turbines can be classified as bulb turbines with a gearbox Publisher Name Palgrave, London. Print ISBN 978--333-34789-8. Online ISBN 978-1-349-06704-6. eBook Packages Engineering Engineering (R0) Buy this book on publisher's site. Personalised recommendations. Universal Joints/Propeller Shafts/Drive Arrangements. Cite chapter Propeller shaft definition is - a shaft that carries a screw propeller at its end and transmits power from engine to propeller

Propeller Shaft Function , types , Components and

  1. On reaching the propeller the current flows down the shaft line until it reaches the earthing arrangement where it is directed back to 'ground' (the ship's hull). Because the shaft earthing arrangement has been fitted correctly, the current has been able to find the path of least resistance throughout its journey without discharging into.
  2. A seal arrangement for rotating shafts, in particular a propeller shaft of a ship which is in contact with water containing impurities, is designed to provide a filter portion substantially adjacent the outermost seal to thereby filter dirt particles out of the water and keep the dirt particles out of the vicinity of the seal. Such a filter can be made from a sintered material and can.
  3. The propeller shafts in one layer of the pallet are not in alignment and collision between the flanges affect the performance of propeller shaft in long run, 3.3.2 TROLLEY ARRANGEMENT The main problems in this trolley are : 1. The trolley is not user friendly
  4. Regulates air supply to increase the head pressure of the sterntube gravity tankDesigned for vessels where structure and layout do not allow for installation..

This can result in spark erosion in the shaft bearings and gear. Propeller shaft grounding provides a very low electrical resistance to the hull, preventing erosion damage. It also includes the propeller to the boat's cathodic protection system. Silver slip ring Silver slip ring arrangement for shaft. The system consists of a slip ring with. A drive shaft, driveshaft, driving shaft, tailshaft (Australian English), propeller shaft (prop shaft), or Cardan shaft (after Girolamo Cardano) is a component for transmitting mechanical power and torque and rotation, usually used to connect other components of a drivetrain that cannot be connected directly because of distance or the need to allow for relative movement between them The propeller shaft withstands the full accelerating power comes from the gear box. Material of Propeller shaft. It is made of hardened steel and in tubular form. Two propeller shafts are used if the vehicle length is more. Bearing is fitted between the centre of two propeller shafts.Propeller shaft is generally made up of alloy steel Propeller Hub - A central covering that is found in the middle of the propeller designed to cover the locking propeller nut securing. Propeller Shaft - A rotational shaft, driven from a main engine source, which generates propeller movement. Multiple screw vessels will have a multiple propeller shaft arrangement As a result, the length of the propeller shaft is reduced, along with the stern tube bearing span used to support it. In this case, the shaft flexibility is reduced, the reaction influence number is increased, and the point load of each bearing is easily influenced by change in displacement. it is difficult to adjust the shaft arrangement.

Proper Propeller Removal | Steve D'Antonio Marine Consulting

The Propeller Shaft Description Your Online Mechani

A coupling-shaft-coupling arrangement is commonly called a cardan shaft or if the couplings are rubber based, a flexible shaft. The majority of the couplings supplied by Twiflex are for use in a shaft arrangement. Shafts are used when there is a need to bridge a distance between two pieces of equipment The propeller is fitted onto a taper on the tailshaft and a key may be inserted between the two: alternatively a keyless arrangement may be used. A large nut is fastened and locked in place on the end of the tailshaft: a cone is then bolted over the end of the tailshaft to provide a smooth flow of water from the propeller

The propeller is not on the same shaft as the basic engine turbine and compressor. [Figure 14-5] Unlike the fixed shaft engine, in the split shaft engine the propeller can be feathered in flight or on the ground with the basic engine still running. The free power-turbine design allows the pilot to select a desired propeller governing r.p.m. propeller hub blade hull shaft arrangement inboard. INBOARD MOTOR. An engine mounted within the hull of a vessel, usually driving a fixed propeller by a shaft protruding through the stern. Generally used on larger vessels. See also stern drive and outboard motor

Understanding Stern Tube Arrangement on Ship

Marine propeller shaft - Thrust blocks arrangement Thrust blocks : The main thrust block transfers forward or astern propeller thrust to the hull and limits axial movement of the shaft. Some axial clearance is essential to allow formation of an oil film in the wedge shape between the collar and the thrust pads (Figure 8.6) Certificate. On completion of the training program, the student will be awarded: → A Certificate of Propeller and Shaft Installations, issued by Bureau Veritas Solutions Marine & Offshore.. The Certificate of Propeller and Shaft Installations, is obtained after completing the course and passing the online test.. Presentation. This training course provides general information on the ship's. The propeller of the ship is fitted at the aft and attached to a crankshaft coming from the main engine. This is done so that the rotating motion of the Main Engine can be converted into thrust to propel the ship. The propeller shaft or tail shaft is supported by a bearing arrangement which acts as an intermediate phase between the sea and the.

Propeller and Propeller Shaft 1. Describes the arrangement of thrust shaft, intermediate shafts and tailshaft 2. Explains how propeller thrust is transmitted to the hull 3. Describes how the propeller shaft is supported between the thrust block and the stern tube 4. Sketches and describes an oil-lubricated stern-tube bearing Describes how the propeller is secured to the tail shaft 6 P a r t 6 C h a p t e r 9 C h a n g e s-c u r r e n t Rules for classification: Ships — DNVGL-RU-SHIP Pt.6 Ch.9. Edition July 2016, amended January 2017 Page 3 Survey arrangements Reconditioning of shafts. Complete reconditioning of all kinds of marine shaft sealing systems. Reconditioning of propeller hubs. Machining of stern tubes on-site. Centrifugal casting of white metal bearings. Manufacturing of new liners and bushes in stainless steel and bronze. Dismantling and assembling of propeller equipment This arrangement consists of three high-strength threaded rods and a plate that uses the propeller shaft end as its fulcrum. The rods are screwed into matching threaded holes that have been bored and tapped in the aft end of the propeller hub

History and Technology - Shafting a Ship - NavWeap

  1. Propeller shaft general arrangement & installation The simplistic view of the merchant ship main propulsion shaft installation is that the system is set up with initial straight alignment and remains in that state during the lifetime of the ship, unless affected by accident or wear
  2. Arrangement and installation - Shaft alignment o Alignment calculation o Shaft alignment sighting o GAP and SAG method o Bearing loads o Alignment checking after chocking Material tests, workshop inspections and testing, certification Propellers o Classification requirements o Propeller types o Geometry of propeller o Material
  3. 2. Propeller shaft nearing arrangement Founded in 1970, the Caravan Stage Company [Caravan] travelled in Canada and the U.S.A., entered a community with horse-drawn gipsy-style caravan carriages, pitched a large (24 m diameter) decorated tent in a park, and using the caravans in the tent as their scenery performed self-scripted plays
  4. A propeller shaft often gets damaged, when the shaft line arrangement suffers failures. Damages also occur during shaft redrawal or when removing the couplings etc. MarineShaft can repair any type of damages on shafts. No matter what caused the damage, we have the knowhow and workshop equipment to fix your shaft problem..
  5. Marine Propeller Shaft / Propeller Shaft / Stern Tube Arrangement , Find Complete Details about Marine Propeller Shaft / Propeller Shaft / Stern Tube Arrangement,Propeller Shaft,Propeller Shaft,Stern Tube Arrangement from Shafts Supplier or Manufacturer-Taizhou Sanyang Heavy Machinery Co., Ltd
  6. The propeller consists of several blades held in place by a central hub. The propeller hub holds the blades in place and is connected to the engine through a propeller drive shaft and a gearbox. There is also a control system for the propeller, which will be discussed later. Modern propellers on large turboprop airplanes typically have 4 to 6.
  7. A propeller is a mechanical device with blades that spins around a shaft to produce necessary thrust to propel the ship. The propulsion system with shaft, engine, and propeller moves the ship based on Newton's third law of motion. The propeller pushes the water backward while the water around pushes the ship forward with equal force

Propulsion layouts shippipedi

  1. 2 • When developing a shafting arrangement the provisions for removing propeller shaft from the stern tube must be considered, • Short propulsion shafting usually generates excessive torsiona
  2. The Hundested propeller assemblies make use of a concentric shaft arrangement just like the Helseth equipment, and it is therefore 100% compatible with the larger Sabb gear offerings. A Hundested installation can alternately make use of a standard reduction gear combined with a Hundested CP 'control box' in the drive line (rather than a 'servo.
  3. Craig Carter, Director of Marketing and Customer Service, Thordon Bearings, said: Based on our cruise installations to date, a seawater-lubricated propeller shaft system typically has a wear.
  4. The propeller shaft can be subjected to a number of loading types during use, including torque moment, bending moment, axle thrust force and transverse load. The risk of failure to the system can be increased by weather and sea conditions due to the fact they have a direct effect on the wear, tear and life time of a propulsion shaft
  5. I'm looking for information on propeller shaft design for a pusher prop. I have a belt-driven system where the pulleys mount directly to the propeller, so the shaft is more of a free-wheeling axle than it is a power-transmitting shaft. As such, I only have bending moments to worry about. Thus..

Ship Propeller and Shafting Syste

  1. Propellers and Shafting for Sustainable Shipping: 10.4018/978-1-4666-4317-8.ch004: The importance of the line shafting, tailshaft, propeller, and thrust shaft cannot be over-emphasised. Failure of any one of them will rend the shi
  2. Thordon's COMPAC propeller shaft bearing installed with the Bearing Condition Monitoring System. Image courtesy of Thordon Bearings. Two Super Eco 2700 containerships being built for Singapore-headquartered X-Press Feeders will be launched with complete water lubricated propeller shaft arrangements supplied by Thordon Bearings
  3. Propulsion arrangement (single screw, multiple screw) Immersion of propeller shaft; Any ice class requirements; 2.0 Propeller Diameter. Generally, you want the largest propeller diameter possible. What limits the propeller diameter? Propeller immersion. The bottom of the propeller generally aligns with the bottom of the ship
  4. The phrase propeller shaft has somewhat different meanings between British and North American English. In North American usage, a propeller shaft has a propeller attached to one end. A propeller is an assembly of helical blades which, when rotat..
  5. The three types of reduction gearing systems most commonly used for aircraft propeller are spur planetary, bevel planetary, and spur and pinion. Whenever the speed of the blade tips approaches the speed of sound, the efficiency of the propeller decreases rapidly. In some engines, the bell gear is mounted on the propeller shaft, and the planetary pinion gear cage is held stationary
  6. Ship shaft alignment and operation services. DNV experts perform root cause analysis for ship and MOU shaft alignment and aid owners/yards in obtaining safe, compliant shaft alignment. An inadequate alignment of the propeller shaft often results in the late delivery of newbuilds, and costly off-hire due to damage or failure of the stern tube.

Prop shaft tapered roller bearing; relative bearing life versus mounting setting and geometric spread . . 5.4-4 Placement of oil Jet at cone's smaller end for mor 9.propeller shaft, tail shaft, 10.plummer Mock, pillow block, shaft block, 11.intermediate shaft, 12.thrust shafts Cargo ship: general structure, equipment and arrangement Container ship: general structure, equipment and arrangement Anchor, Mooring gear Construction of ship Multi-purpose ship Equipment on forecastle deck of ship.

2 piece driveline angles and 5” rear dropEdge modification | Services & Support | Nakashima

Marine Propeller Shafting and Shafting Alignment - Part 1

The propeller shaft carries the power from the engine, clutch and transmission unit to the driving wheels of the vehicle, through the final drive and differential unit. Functions of the propeller shaft. In most automotive vehicles, the engine is located at the front and the rear wheels of the vehicle are being driven. This arrangement. The figure shows an arrangement of a heavy propeller shaft in a ship. The combined polar mass moment of inertia of the propeller and the shaft is 100 kg.m 2. The propeller rotates at ω = 12 rad/s. The waves acting on the ship hull induces a rolling motion as shown in the figure with an angular velocity of 5 rad/s A recent inspection of the twenty-year-old water-lubricated propeller shaft bearings installed on a twin-screw cruise ship were found to be within classification society parameters and suitable.

The following example will be taken as a sample drive shaft design problem throughout this series of article: Example problem: Design a cardon shaft with the orientation shown as below: Automobile Propeller Shaft Design Example Arrangement . Given: Max. Transferred Torque (T)=3500 Nm . Length of shaft (L)=1250 mm . Inclination angle (θ)=2 Deg The propeller shaft is also rotating counter clockwise. The engine torque is 180 ft-lb and the transmission ratio is 3 (such that the propeller shaft speed is 1/3 the engine speed). The transmission weighs 60 lbs. Question: 3. Consider the engine-transmission-shaft arrangement shown below. The engine is rotating counter clockwise when viewed. 4. Parallel shafts with a small axial separation provide less propeller support. Propeller support is improved if the smaller propeller separation is used with a rearwards converging shaft arrangement. This also makes engine arrangement easier. 5. Recovery of rotational energy with both propellers turning in the same direction. 6 Wärtsilä Controllable Pitch (WCP) propeller systems provide excellent performance and manoeuvrability, and are recommended for vessels with frequent sailing routes that involve multiple operating conditions. These can be, for example, vessels requiring full power in both bollard pull and freesailing conditions, or that make frequent port calls Carisbrooke now operates the COMPAC seawater lubricated propeller shaft arrangement on a total of eight vessels. Based on our experience with these bearings in continuous service for the last 6 years we will ensure that future building specs incorporate the Thordon system, added Capt. Merritt

Construction of propeller shaft Car Constructio

AZIPOD (Azimuthing Podded Drive)Development of the Screw Propeller - Shipping Wonders ofElectric Azimuthing Propulsion Pods – Welcome to PT

While the propeller itself may be operating in somewhat disturbed air due to the passage of the fuselage ahead of it, and thus have a slightly lower efficiency, the overall system of the aircraft/propeller arrangement is more efficient with the tail propeller Most commonly used propellers on cargo vessels have four or five propeller blades, but six blades have been used. The propeller may have a diameter of more than nine metres and a weight of 130 tons. The most commonly used materials are stainless steel or a bronze alloy. These propellers are mounted on a propeller shaft that turns on demand P a r t 6 C h a p t e r 6 C h a n g e s-c u r r e n t Rules for classification: Ships — DNVGL-RU-SHIP-Pt6Ch6. Edition October 2015 Page 3 Cold climate DNV GL AS CHANGES - CURREN A Cardan shaft consists of a propeller shaft with two (less frequently one) Cardans. If the Cardan Cross Joint Rolling Mill propeller shaft is connecting mechanisms between which the angle and distance vary (for example, the transmission and rear-axle drive of a motor vehicle), Cardan Shaft Heavy Duty Universal Joint, overhang balance is provided i The propeller shaft bearing clearance shall be ascertained. 1.3.3 The following securing arrangements shall be examined: — propeller nut — propeller hub coupling bolts or nuts, if bottom survey afloat, only the securing of the protective arrangement shall be examined — propeller blade bolts. 1.4 Thrusters 1.4.1 All thrusters shall be. The best propeller speed for efficient operation is in the region of 80 to lOOrev/min. The turbine or engine shaft speed is reduced to that of the propeller by the use of a system of gearing. Helical gears have been used for many years and remain a part of most systems of gearing