Bridge Management - Ship's Compass Flashcards
Which SOLAS chapter and regulation and MGN details the carriage requirements for ships compass?
SOLAS chapter V, regulation 19 and MGN 610
What gross tonnage vessels are required to carry a gyro compass?
More than 500gt
When should the magnetic compass be adjusted? (5)
When the ship is built
The ship undergoes structural repairs/modification that could affect compass
Electronic equipment is added/removed that could affect the compass
The compass becomes unreliable
Every 2 years except when regular compass errors are taken
What is Variation?
Difference between Magnetic North and True North (Earth’s magnetic field)
What is Magnetic dip?
The angle that the earths field makes with the horizontal
What is Directive Force?
The desire of the compass needle to align itself with the earth’s magnetic field
What is Hard Iron (Permanent Magnetism)?
Not readily magnetised but will be permanently magnetised after magnetism influence removed
What is deviation?
Difference between Compass North and Magnetic North (Magnetic influence of the ship’s structure)
What is Soft Iron (Induced Magnetism)?
Readily magnetised but will lose magnetism after magnetism influence removed
What is Force P?
The fore and aft component of the ship’s permanent magnetism
What is Force Q?
The athwartships component of the ship’s permanent magnetism
What is Force R?
The vertical component of the ships permanent magnetism
What is the purpose of the binnacle?
Houses the ship’s compass
What is the binnacle made of?
Non-magnetic materials that will not corrode, traditionally wood and brass although contemporary binnacles made of fibreglass
Where is the binnacle located?
The vessels centreline, clear of sources of interference
Which way does the magnetic field run?
Out of the red and into the blue
What happens when two identical poles are offered up to one another?
They repel
What happens when two opposite poles are offered up to one another?
They attract
Where does the compass needle point to?
Magnetic North
What happens to H and Z at the magnetic equator?
Z is at it’s smallest, H is at its largest
What happens to H and Z at the magnetic poles?
Z is at it’s largest, H is at it’s smallest
What happens to directive force if H decreases?
Directive force will decrease
What happens to directive force if H increases?
Directive force will increase
What do we call it when directive force is weak?
Sloppy