week 5 pt.2 (Rudders, Thrusters, and propellers) Flashcards
is a primary steering device used on ships, located at the stern, submerged in water.
It functions by deflecting the flow of water, creating a turning force (yaw) that changes the ship’s direction.
The effectiveness of the rudder is dependent on its size, shape, and the ship’s speed.
Rudder
Is basically a rudder plate that is fixed to the rudder stock only at the top of the rudder.
oCharacteristic: The rudder area is partially forward and partially aft of the rudder stock (the axis about which the rudder rotates).
oPurpose: Provides easier steering as the forces on the rudder are more balanced, requiring less effort to turn.
oShip Type: Commonly used on medium to large vessels, such as tankers, container ships, and bulk carriers.
➢Balanced Rudder
means that the rudder is partly balanced and partly unbalanced
oCharacteristic: Similar to the balanced rudder, but with a smaller area forward of the rudder stock.
oPurpose: Offers a compromise between the ease of operation of a balanced rudder and the simple construction of an unbalanced rudder.
oShip Type: Often found on older or simpler designs of cargo ships and smaller vessels.
Semi – balance rudder
Have their stocks attached at the forward most point of their span
oCharacteristic: The entire rudder area is aft of the rudder stock.
oPurpose: Simpler and cheaper to construct but requires more force to operate since the entire area resists movement.
oShip Type: Typically used on smaller vessels like tugs, fishing boats, and older ships.
Unbalance rudder
A spade rudder is basically a rudder plate that is fixed to the rudder stock only at the top of the rudder.
oCharacteristic: A rudder that is entirely unsupported at its lower end, giving it a ‘spade’ appearance. It is connected to the ship only at the top via the rudder stock.
oPurpose: Provides high maneuverability and is commonly used on modern ships where precise steering is essential.
oShip Type: Frequently found on high-speed vessels, including naval ships, cruise liners, and container ships.
Spade Rudder
is a specific type of multi-section rudder used on boats and ships.
oCharacteristic: A rudder with a hinged aft section (flap) that increases the effective turning angle and thus the lift generated.
oPurpose: Enhances steering at low speeds and in tight spaces, offering greater control and maneuverability.
oShip Type: Commonly used on vessels requiring high maneuverability, such as ferries, tugs, and offshore vessels
Flap Rudder
is a specific type of profiled rudder used on certain boats and ships
oCharacteristic: A high-lift rudder with a unique, curved shape designed to maximize the flow of water over the rudder surface.
oPurpose: Provides enhanced steering capability, especially at low speeds or in reverse.
oShip Type: Often used on vessels where maneuverability is critical, such as harbor tugs and offshore support vessels.
Schilling rudder
A fixed, annular forward extending duct around the propeller.
oCharacteristic: A rudder placed within a Kort nozzle, which is a ducted propeller system that increases thrust and steering efficiency.
oPurpose: Improves propulsion and maneuverability, particularly in vessels that operate at lower speeds.
oShip Type: Common on tugs, trawlers, and other vessels that require strong, controlled propulsion.
Kort Nozzle with Rudder
is often found on vessels with twin propellers and is designed to provide improved maneuverability and steering control.
oCharacteristic: Two rudders positioned on either side of the ship’s propeller(s).
oPurpose: Provides better maneuverability, especially in twin-screw ships, by allowing differential steering.
oShip Type: Common on large ships with twin propellers, such as naval vessels, ferries, and cruise ships.
Twin Rudders
For all rudder types, the watertight construction of the rudder stock is critical to maintain the integrity of the ship’s hull.
The rudder stock typically passes through the hull via a rudder trunk, which is a watertight housing designed to prevent water ingress.
The trunk is fitted with gland seals and packing around the rudder stock to ensure a tight seal, allowing the stock to rotate without allowing water to enter the hull.
Watertight Construction of Rudder Stock:
A bow thruster is a transversal propulsion device installed near the bow (front) of a ship. It consists of a propeller mounted in a tunnel that runs through the hull, allowing the ship to move laterally (sideways) without using the main propulsion or rudder.
oPurpose: Bow thrusters are primarily used to improve a ship’s maneuverability when docking, undocking, or navigating through narrow channels.
oUsed by: Large commercial vessels (like tankers and container ships), passenger ships (like cruise liners), offshore supply vessels, and yachts
Bow Thruster:
is a transversal propulsion device that enables the vessel to move laterally, but from the stern.
oPurpose: Stern thrusters work in conjunction with bow thrusters to provide even greater control and precision in maneuvering. They are particularly useful for large vessels where turning the ship’s stern is challenging
oUsed by: Large vessels like oil tankers, cruise ships, ferries, and large yachts.
Stern Thruster
The shaft tunnel is a critical part of a ship’s engineering design, particularly in vessels where the main propulsion machinery is located amidships (in the middle of the ship), and the propeller is located aft (at the rear).
The shaft tunnel houses the propulsion shaft, which transmits power from the engine to the propeller.
Given its importance, the shaft tunnel must be constructed to be watertight to prevent water ingress into the engine room and other critical areas.
Watertight Construction of the Shaft Tunnel
A propeller is a crucial component of a ship’s propulsion system, converting rotational energy from the ship’s engine into thrust, which propels the vessel through water.
The design, type, and size of a propeller greatly influence the efficiency, speed, and maneuverability of a ship.
Propeller
A propeller is a crucial component of a ship’s propulsion system, converting rotational energy from the ship’s engine into thrust, which propels the vessel through water.
The design, type, and size of a propeller greatly influence the efficiency, speed, and maneuverability of a ship.
Propeller
