Magnetic compass

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Image
The magnetic compass is fitted on the upper bridge exactly center line of the ship   It is referred to as standard compass     1. D ry C ard    2. W et C ard   A compass point north because all magnets have two poles north pole, south pole.   The north pole of the one magnet attracted towards the south pole of another magnet     DRY CARD COMPASS   A light aluminum ring about 254mm in diameter is attached to a brass hub by silk cord which is threaded in and out through holes in the ring.   This tight silk cord is act like bicycle wheels.   There is no other connection or support between the ring and the hub.   Silk cord is used because it doesn’t shrink or stretch due to moisture or change in atmospheric temperature.     Card support: -     The bottom of the hub has small cap fi tt ed with a sapphire bearing surface.   This rests on a pivot tipped with iridium which is hard nonmagnetic metal....
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Bulk head

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Bulk heads

Aft Peak Bulkhead

A term applied to the first main transverse watertight bulkhead forward of the stern. The aft peak tank is the compartment in the narrow part of the stern aft of this last watertight bulkhead.


Bulkhead Deck

The uppermost continuous deck to which transverse watertight bulkheads and shell are carried.

Bulkhead Structure

The transverse or longitudinal bulkhead plating with stiffeners and

girders.


Cargo Hold Bulkhead
A boundary bulkhead separating cargo holds.


Collision Bulkhead

Is the foremost main transverse watertight bulkhead.


Tank Bulkhead


Is a boundary bulkhead in a tank for liquid cargo, ballast or bunkers.


Wash Bulkhead

It is a perforated or partial bulkhead in a tank.


Watertight Bulkhead

Is a collective term for transverse bulkheads required for subdivision of

the hull into watertight compartments.



Margin line

Is an imaginary line drawn parallel to and at least 76mm below the upper surface of the bulkhead deck at side a ship is deemed to remain afloat after flooding. If calculations show that the margin line is not submerged used for passenger ship subdivision criteria.




Vertical partitions that divide the hull into separate compartments are called bulkheads.

Some are watertight. These water-tight bulkheads are so arranged that in case of accident at sea, water would be confined to one compartment only.

The collision bulkhead in the front end is constructed to withstand heavy strain and shock in case the bow is staved in.


The three basic types of bulkheads found on most ships are watertight, non-watertight and oil tight or tank bulkheads.




Purpose of bulkheads:

  1. Subdivision, to divide the ship into a number of compartments.
  2. Contain flooding in the event of damage.
  3. Transverse strength member, provide structural strength, some of the bulkhead do not offer any structural strength and act as ‘screens’ to divide units of accommodation, store.
  4. Protection against racking stresses
  5. Effective barrier against the spread of fire in holds and E/R.
  6. Resisting any tendency for transverse deformation of the ship


Transverse Watertight Bulkheads:

- subdivide a ship against flooding and spread of fire

- Support decks

- Resist racking stresses

- Maintain transverse form

- Number and spacing of WT bulkheads governed by statutory requirements


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