Marine scientia

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....

A lifebuoy is a ring shaped floating life preserver. All ships must carry adequate number of lifebuoys as per SOLAS regulation. Lifebuoys provide an additional flotation to crew/passengers until they are rescued. lifebuoy specifications: Have an outer diameter of not more than 800 mm and an inner diameter of not less than 400 mm. Be constructed of inherently buoyant materi al. Be capable of supporting not less than 14.5 kg of iron in fresh water for a period of 24 hours. Have a mass of not less than 2.5 kg and more than 6kg. Not sustain burning or continue melting after being totally enveloped in a fire for a period of 2 seconds. Be constructed to withstand a drop into t he water from the height at which it is st owed above the waterline in the lightest seagoing condition or 30 m, whichever is the greater, without impairing either its operating c apability or that of its attached components. If it is intended to operate the quick re lease arrangement provided for the self-...

The water tightness of hatch cover is imperative to protect the cargo and avoid large cargo claims. Mainly there are three methods for testing the weather tightness of hatch covers. 1)chalk test 2)water hose leak detection test 3)ultra sonic leak detection test. 4)Visual inspection. 1)CHALK TEST:- The top edge of every compression bar is covered with chalk. Hatches are then fully closed and reopened . The rubber packing is examined for a chalk mark, which should be run continuously along the packing's center. Gaps in the chalk mark indicate lack of compression. Chalk testing merely indicates if the hatch is aligned and compression achieved . It will show whether compression bar is adequate and therefore it is not a test for weather tightness. 2)WATER HOSE LEAK DETECTION TEST: Water hose test is used to determine weather tightness of hatch cover. The general procedure for hose t...