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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LOADLINE

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LOAD LINE:-

Load Line is a special marking positioned amidships. All vessels of 24 meters and more are required to have this Load line marking at the centre position of the length of summer load water line.

For timbre carrying ships seperate loadline are used.because timbre will give extra buoyancy to the ship.so we can load more timbre.so there will be small change in the load line marking.

S – Summer :- It is the basic freeboard line at the same level as the Plimsoll Line. Other load lines are marked based on this Summer freeboard line.


T – Tropical :- It is 1/48th of summer draft marked above the Summer load line.


W – Winter :- It is 1/48th of summer draft marked below the Summer load line.


WNA – Winter North Atlantic :- It is marked 50mm below the Winter load line. It applies to voyages in North Atlantic ( above 36 degrees of latitude) during winter months. Ship’s length not exceeding 100 m.


F – Fresh Water :- It is the summer fresh water load line. The distance between S and F is the Fresh Water Allowance (FWA)mm = Displ / (4 x TPC).


TF – Tropical Fresh Water :- It is the fresh water load line in Tropical. It is marked above the T at an amount equal to FWA

DRAFT MARKS:
There are six draft marks.forward,aft,midship on both sides.the true draft is calculated by using draft survey calculation(that you will study later).This draft mark may be not in the exact aft/forward/midship perpendicular.therefore some corrections should be applied.(that also we study later)

When the markings are in meters, the main meter marks are marked as numbers followed by the letter M such as 8M, 9M, 10M. In between the metric marks are numeral markings such as 2, 4, 6 and 8 to indicate 20 cm, 40cm, 60 cm and 80 cm. The height of each mark is 10 cm and the distance between the mark in 10 cm.

If the water is just in line with the LOWER EDGE of the mark 10M, the draft is 10.0 meters. If the water is in line with the top edge of 10 M, then the draft is 10.10 meters and so on.

The size of each draft mark is 10-cm high and 2-cm wide.



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