Marine Steering Gear Systems

Study Notes

Steering Gear Introduction

A steering gear is essential for steering a ship during its voyage, and its design must be perfect to avoid malfunction or failure.
The basic requirements of a steering gear include:
- Being continuously available
- Moving the rudder rapidly to any position in response to bridge orders
- Holding the rudder in the required position
- Relieving abnormal stress and returning the rudder to its required position
- Maintaining the ship's course despite wind and waves

Steering Gear Principles

The statutory requirements for steering gear systems are specified in SOLAS 1974 and amended in 1981.
All ships must have two independent steering gear systems: one main and one auxiliary, unless the main gear has duplicate power units and connections.
The auxiliary gear must be power-operated in passenger ships with rudder stocks over 230mm in diameter and in cargo ships with rudder stocks over 250mm in diameter.
The auxiliary gear must be capable of moving the rudder from 15 degrees on one side to 15 degrees on the other side in not more than 60 seconds.
The main steering gear must be powerful enough to move the rudder from 35 degrees on one side to 35 degrees on the other side when the ship is fully loaded and running at maximum speed.
The time taken to move the rudder from 35 degrees on either side to 30 degrees on the other side must not exceed 28 seconds.
One power unit is required on passenger ships, and two on cargo ships.
An alternative steering position is required, remote from the main steering position.
Failure of either control system must not put the other system out of action.
All steering gears must have a locking or brake arrangement to hold the rudder steady when necessary.
Power steering gears must be fitted with shock-relieving arrangements.

Special Requirements for Tankers

The main steering gear of tankers, gas carriers over 10000 tons gross tonnage, and all other vessels over 70000 tons gross tonnage must comprise two or more identical power units.
The system must be capable of steering the ship at maximum ahead speed and capable of moving the rudder from 35 degrees to 35 degrees.

Description

Test your knowledge of steering gear systems used in ships, including their design requirements and importance in ensuring safe navigation. Learn about the key components and functionality of steering gears and their role in preventing accidents.