Question and Answers

    Question
    marinetales July 24, 2021
    The ganger length is the term given to the few additional links found between the Anchor Crown ‘D’ Shackle and the first (1st) joining shackle. The ganger length may or may not have a swivel piece within it.
    marinetales July 24, 2021
    Anchor Crown ‘D’ shackle, shank, arms, fluke, pea or bill, crown, tripping palms. The lower part of the anchor attached to the shank is termed the ‘head’ of the anchor.
    marinetales July 5, 2021
    Advantages of Controllable Pitch Propeller (CPP) are - (a) Immediate control of the vessel by the OOW. (b) The ship can be stopped, without stopping the engine. (c) Shaft alternators can be used with a constant speed shaft, thereby saving on the cost of auxiliary fuel for generators. (d) Air start bottles are unlikely to cause a problem during continuous manoeuvres. (e) Bridge wing and central control positions provide better ship handling.
    marinetales July 2, 2021
    An ‘oxter plate’ is the ‘S’-shaped plate found in a position on the ship’s hull, on either quarter. It is a shell plate, sited from above the propeller towards the gunwale
    marinetales June 17, 2021
    1. Midship section (exposed to hogging and sagging) 2. Tank side bracket, beam knee (exposed to racking stresses) 3. Bulkhead, floor and frame (water pressure) 4. Plating of bows (exposed to panting) 5. Bottom plating and girders at one quarter of the ship from stem (exposed to pounding)
    marinetales June 17, 2021
    Girders are one form of longitudinal stiffeners. These are - • Big size steel plate (or sometimes beams) connected to bottom of the ship • Runs in fore and aft direction • strengthen the ship against bending moment Girders are also named according to its location. The girder at the center of the ship is called center girder. In double bottom tanks, the thick solid metal plate that divides the ballast tanks into port and starboard tank is the center girder.
    seawizard June 10, 2021
    1. CAP stands for Condition Assessment Program 2. CAP is the inspection of the vessel to determine it's technical condition 3. CAP is based on a Rating system and ratings are given to the vessel in accordance with its condition 4. CAP is NOT a Classification requirement however it was introduced and now required by Oil Majors 5. Tankers of 15 years and above are required to have CAP certificate issued 6. CAP can be effectively applied to any type, size and age of ship A CAP survey consists of - 1. Hull structure assessment 2. Machinery assessment 3. Cargo systems assessment 4. Combining Class CAP survey with the vessel’s structural survey provides minimal disruption to the operational schedule 5. CAP rating is given from 1 to 4 where 1 stands for new building, 2 stands for good, 3 stands for satisfactory and 4 stands for poor
    seawizard June 5, 2021
    Imagine a situation when a vessel lists to one side due to flooding of certain compartment(s). Consider an arrangement whereby the opposite compartment of the vessel can be flooded and still rendering the vessel to be stable. This arrangement is called Cross flooding arrangement and is mostly used on Passenger ships.
    seawizard June 1, 2021
    When a ship complies with the above four regulations as followed by the B-60 ships such that when a transverse bulkhead is damaged and the two adjacent Forward and Aft compartment floods simultaneously and the ship complies with special regulation for Type A ships, except hatch covers are weather tight. In this situation the freeboard can be reduced to similar sized type A ship. Such ship is called as Type B-100 Ship
    seawizard June 1, 2021
    For a type B ship to be assigned as a type B-60 ship, following four requirements needs to be fulfilled - 1. Adequate crew protection 2. Adequate freeing arrangements 3. Fixed steel hatch covers with adequate strength and sealing 4. Ship when fully loaded shall be able to withstand flooding of any compartment transversally and longitudinally; then In this case the freeboard of the ship can be reduced to 60% of the freeboard difference between the Type A and Type B ship of same length and size. Hence this ship is called Type B-60 ship.
    seawizard June 1, 2021
    All other ships except Type A ships are called Type B ships. They follow the table B for the assignment of the freeboard. According to this table, the freeboard can be increased or decreased. Sometimes the freeboard can be reduced to as much as that for Type A ship of same length and size. Type B ships are of two types B-60 ships and B-100 ships.
    seawizard June 1, 2021
    Type A ships are - 1. Designed to carry liquid in bulk. 2. Has a high integrity of exposed deck with small openings to cargo compartments, which are covered with W/T gasket covers of steel, low permeability of cargo spaces. 3. If ship>=150 mtrs she must be able to withstand flooding in any one compartment longitudinally and more than one compartment transversely and shall remain afloat in 4. condition of equilibrium. 5. Machinery spaces treated as a floodable compartment (p=85%) for other compartments (p=95%). 6. They should strictly follow Table A for freeboard assigned which cannot be altered. 7. Machinery spaces to be enclosed in casing protected by the W/T doors.
    marinetales May 28, 2021
    Length between perpendiculars is the length of a ship along the summer load line from the forward surface of the stem, or main bow perpendicular member, to the after surface of the sternpost, or main stern perpendicular member. When there is no sternpost, the centerline axis of the rudder stock is used as the aft end of the length between perpendiculars. Measuring to the stern post or rudder stock was believed to give a reasonable idea of the ship's carrying capacity, as it excluded the small, often unusable volume contained in her overhanging ends. Length between perpendiculars is extensively used in Draft Survey calculations onboard ships
    marinetales May 26, 2021
    Torsional stress arise when the ship is loaded / discharged unevenly along the port and starboard line. It tends to twist the ship along the centre line. Container ships mostly suffer from these kind of stresses. Torsional boxes are constructed in container ships so as to reduce the effect of torsional stresses.
    marinetales May 26, 2021
    There are three methods used for checking the weather tightness of the hatch covers - 1. Hose test : Water spray from a nozzle 12mm in diameter is sprayed over the point where the hatch cover touches the hold coaming and joints in the hatch cover. Water is applied from a distance of 1-1.5 meters and usually 4-6 bars pressure. This test is required to be carried out by two persons and cannot be carried out in sub zero temperatures. 2. Chalk test : it is the oldest and the most traditional method of doing the test. It is used only for testing the joints along the compression bar. Chalk powder is applied to the steel backs and hatch cover closed and tightened and then the hatch cover is opened again to check the gaps in chalk mark which shows the position of the leakage. The disadvantage of this test is it cannot check the degree of tightness between the rubber packing and compression bar. Only an chalk impression cannot guarantee weather tightness. 3. Ultrasonic test : this is the most accurate method of testing the weather tightness. An ultrasonic transmitter is placed at the tank top of a empty hold. The hatch covers are now closed and transmitter is switched on. A person outside on the deck uses a receiving probe and passes over all hatch cover joints. An alarm is given when the leak is detected.
    marinetales May 25, 2021
    There are primarily four types of Gas carriers as follows - 1. Type 1G : Requires maximum preventive measures to preclude escape of cargo 2. Type 2G : Requires significant preventive measures to preclude escape of cargo 3. Type 2PG : Requires significant preventive measures as Type 2G but less than or equal to 150 mtrs 4. Type 3G : Requires moderate preventive measures to preclude escape
    seawizard June 13, 2021
    The girth of the ship decreases toward the ends and so the width of plates must be decreased in these parts. To save making the plates too narrow at the ends of the ship, it is usual to run a number of pairs of adjacent strakes into one. This is done by means of a stealer plate. The end-plate of a strake of outside or inner-bottom plating which is dropped out as the girth of the vessel narrows toward the ends. It is place where 2 strakes merge into 1.
    marinetales May 17, 2021
    A Panting beam is fitted athwartship in the bow or stern of the vessel to prevent panting of the sides.
    marinetales April 6, 2021
    Gross tonnage Gross Tonnage is a measure of the ships total interior volume and is calculated by multiplying the interior volume “V” of the ship in cubic meters by a variable known as “K” (which varies depending on the ships overall volume). Gross Tonnage is not to be confused with Gross Registered Tonnage which is explained below. Net tonnage Net Tonnage is a measure of the total interior volume of a ship’s cargo spaces and is calculated in much the same way. The total volume of designated cargo spaces in cubic meters is then multiplied by varied number of factors resulting in an official net tonnage value.
    marinetales May 18, 2021
    One of a pair of steel reinforcing plates bolted or welded to the sides of a beam or bulkhead joint is called a fish plate.
    marinetales October 26, 2020
    The WNA mark ( Winter North Atlantic mark) is required by the ships lesser than 100 mtrs in length trading in North Atlantic Ocean during the Winter Season. During the first conference on the Loadline convention it was generally agreed that the freeboard of small ships should be especially examined with a view to some increase being made ( in freeboard) . Statistics of ship losses had highlighted the safety problems associated with vessels under 300 ft long and some action was necessary. It was recognized that it was difficult for ships lesser than 100 mtrs ( 328 feet) to provide for an even Compartment subdivision and the deck integrity for these ships should be paramount. North Atlantic Ocean during winter season is primarily Rough and therefore the vessel shall be loaded to a loadline which is even lesser than the Winter mark ( so as to give sufficient freeboard allowance for the size of the ship lesser than 100 mtrs). This was primarily done for safety reasons.
    marinetales May 19, 2021
    The hunting gear mechanism in the steering gear system is a feed back mechanism, which transmits the position of the rudder to the pump control lever, through the floating lever.
    marinetales May 24, 2021
    A thrust block, also known as a thrust box, is a specialised form of thrust bearing used in ships, to resist the thrust of the propeller shaft and transmit it to the hull. The last part of the marine propeller shaft system is the thrust blocks. These blocks support the propeller shafts at regular intervals. These blocks play transfer the excess power from the shafts into the hull of the ship.