Question and Answers

    Question
    marinetales May 28, 2021
    A Single buoy mooring (also known as single-point mooring or SPM) is a loading buoy anchored offshore, that serves as a mooring point and interconnect for tankers loading or offloading gas or liquid products. The parts of a typical SPM includes - 1. Buoy body 2. Mooring and anchoring parts - includes mooring components like Anchors, anchor chains and chain stoppers 3. Product transfer system - hoses etc 4. Other components such as - access to the buoy deck, Fendering to protect the buoy, Lifting and handling equipment to aid materials handling, Navigational aids for maritime visibility, and fog horn to keep moving vessel alert, An electrical subsystem to enable valve operation and to power navigation aids or other equipment. Attached the construction of a typical SPM.
    marinetales May 27, 2021
    Uses of dunnage - To provide protection to the cargo from water damage caused by contact with water from the bilges, other cargo or double bottom tanks It protects moisture sensitive cargoes such as bagged cargo ( eg. coffee, cocoa) or bales (eg tobacco, tea) from sweat, which forms on a ship’s sides and runs off over the decks. to provide air channels between stows to aid ventilation, mainly for refrigerated cargoes to prevent damage to goods through contact with either the ship’s structure or with other cargo to aid in the effective distribution of weight on tank tops of hatch covers to aid in filling void spaces between cargoes, especially unevenly shaped cargoes Types of Dunnage - Floor Dunnage This is mainly used to lift the cargo off the tank top This prevents cargo damage from sweat or moisture running off from other cargo Floor dunnage is laid crosswise and the direction depends on the design of the vessel In ships with large lateral water drainage (bilges), the first layer must be laid cross wise, while ships with fore and aft drainage(wells), the first layer must be laid lengthwise. The dunnage should be laid close together to prevent the cargo from making contact with the tank tops. On modern vessel’s especially reefers permanent deck gratings, made of grooved and perforated aluminum or plywood gratings, are fitted Lateral Dunnage This usually takes the shape of a spar ceiling on a general cargo vessel. These are wooden beams securely connected to the side of the cargo hold. Lateral dunnage prevents contact of the cargo with the ship’s side and so prevents cargo damage due to sweat In the absence of spar ceilings, wooden or criss cross dunnage must be used. Criss Cross dunnage consists of nailed grids, cross wide wooden dunnage being nailed to the vertical uprights (vertical positioned upright beams) Permanent Collapsible Dunnage (PCDs) This comprises of painted or varnished 8’ x 4’ plywood sheets that may be fitted to ship’s sides These sheets are hinged at their base and open out to be secured in a variety of ways Their main purpose is to square off curved ship’s sides and they are particularly useful for the palletized cargo Interlayer Dunnage This separates cargoes from each other, either for the protection of of an underlying cargo from contamination by a top cargo or for the segregation of individual batches of cargo Top Dunnage This generally protects the cargo from contamination damage from the water, hydraulic oil, etc dripping from the weather decks. Top dunnage must also allow for some air circulation and evaporation, especially for 3. hygroscopic cargoes For this reason, top dunnage is usually made from an air permeable material such as paper or jute Side dunnage This is similar to Spar ceiling and provides protection against contamination from sides and prevents mechanical damage Inflatable dunnage This is being used widely on refrigerated ships. This dunnage can be re-used an inflated using compressed air which is readily available on board. Any wooden dunnage that is too fresh or has been exposed to the atmosphere must not be used. While using Wooden dunnage it is prudent to obtain a fumigation certificate for the Dunnage being used stating that the Dunnage has been properly fumigated.
    marinetales May 27, 2021
    A wire rope is condemned if in any length of 8 times the diameter, the total number of visible broken wires exceeds 10% of the number of wires in the wire rope.
    marinetales May 27, 2021
    1. Weather 2. Running tide 3. Strong currents 4. Density of water in which ship is floating 5. Hydrometer calibration 6. Density of water in ballast 7. Displacement for a ship at anchor will be different from when the anchors are housed
    marinetales May 27, 2021
    1. Loaded displacement = Light displacement + cargo + ballast + fuel + slops + fresh waster + constant 2. During initial draft survey we obtain the displacement as per the drafts and calculate the constant of the vessel 3. During final draft survey this constant is used to calculate the amount of cargo loaded using the formula given in I above. 4. Obtain visual drafts forward, midship and aft on both sides. Calculate the length between the marks (from stability booklet) 5. Obtain mean of ford, aft and mid draft 6. Calculate correction to all draft as follows Corr to forward draft = ( trim x distance of ford visual marks from forward perpendicular ) / length between marks Corr to aft draft = (trim x distance of aft visual from aft perpendicular ) / length between marks Similarly obtain corrn to mid marks Apply this correction to ford, mid and aft draft marks and obtain corrected drafts at perpediculars 7. Now calculate the means of means or Quarter Mean draft by following – ( Corr forward draft + Corr aft draft + 6*Corr mid draft ) / 8 8. This draft is called Hydrostatic draft and enter the hydrostatic data tables using this draft to obtain the displacement, TPC, MCTC etc 9. First trim calculation is then calculated by following formula – (Trim x distance of Centre of floatation from midpoint bet perpendiculars x TPC) / LBP This trim could be either positive or negative 10. The second trim correction is then obtained by following formula – (50 x (trim)^2 x (MCTC1-MCTC2))/ LBP MCTC1 = MCTC at 50 cms greater than True mean draft MCTC2 = MCTC at 50 cms lesser than Tue mean draft This correction is always positive. 11.List correction is calculated in tonnes using – Correction = 6(d1-d2)(tpc1-tpc2) Where d1 and d2 are the drafts of immersed and emerged sides respectively And tpc1 and tpc2 are for those respective drafts 12. The result will be Corrected displacement in Salt Water 13. Density correction is then applied to the displacement if the vessel is floating in a water density different than salt water This displacement is then used in the formula mentioned in point No 1 to calculate the cargo loaded / discharged.
    marinetales May 27, 2021
    1. Inform Master. Sound alarm 2. Bilge pumps to be activated and put into use 3. Investigate the cause of leakage (from the adjacent ballast tank or elsewhere). Monitor soundings of the adjacent ballast tanks. 4. Sound all bilges 5. Check for cargo damage (if the cargo is of perishable nature) ascertain damage and inform the owners and charters 6. Check hatch cover condition. Repair if damaged 7. Collect evidence. Perform due diligence and make log entry 8. Repair damages if feasible, else deviate towards port of refuge and seek shore assistance
    marinetales May 27, 2021
    Following steps shall be taken when the breakdown with cargo gear (lifting appliances / cranes etc) is enountered - 1. Stop cargo operation 2. Prevent the movement of cargo, if possible, by taking extra lashings 3. Try ascertaining the fault - whether electrical or mechanical 4. If electrical fault, try reseting the power 5. If not troubleshooting to be carried out by the electrical officer in accordance with the manufacturers instructions 6. Meanwhile, if the weight is hanging in air, it can be lowered by manually overriding the crane brake 7. In case of hydraulic crane, oil levels and pressure shall be checked 8. Limit switches to be checked 9. Inform the terminal, charterers, owners, make an entry into log book. Amend the loading sequence.
    marinetales May 26, 2021
    Following precautions need to be taken while handling Reefer containers - 1. Check the plug points and working and sufficient spares are carried on board 2. A reefer manifest to be obtained from shore and details of the stowage shall be confirmed by the responsible officer and electrical officer 3. Excess number of reefers on multiple socket connections must not be carried 4. Gantry operator shall be aware of the position of reefer machinery and the plug point as the container cannot be turned around later 5. On loading, plug in the reefer and check whether it is working 6. Check the temperature reading and compare it with the set temperature as mentioned in the manifest Container shall be refused if the difference is too large 7. Check the temperature charts/records and check for any difference between the actual temperature and that being recorded 8. Check the ventilator settings , if all OK then accept the container 9. Once container is onboard lash it properly 10. Prior sailing a detailed list of the reefers to be prepared stating their location and temperature settings 11. On failure of any reefer container, the Master should inform the owners and the charterers
    marinetales May 26, 2021
    Following precautions shall be taken while carrying concentrates - 1. Master should allow to load concentrates ONLY when he is provided with Shipper's declaration stating that the Moisture content of the cargo is as per the TML 2. Wet cargoes shall not be loaded at any cost 3. Cargo to be trimmed reasonably well to prevent oxidation and reduce shifting 4. Some concentrates such as sulphides are needed to be sprayed with water in order to prevent oxidation and spontaneous combustion. Care shall be taken so that moisture content is not increased resulting in development of flow state 5. Shipper needs to provide a certificate to the Master stating the TML, MC and FMP of the cargo 6. In case the cargo is exposed to precipitation than test samples must be taken just prior loading and decision shall be made accordingly to load or not
    marinetales May 26, 2021
    Concentrate is the product generally produced by metal ore mines. The raw ore is usually ground finely in various comminution operations and gangue (waste) is removed, thus concentrating the metal component. The concentrate is then transported to smelters where it is used to produce useful metals. The hazards of Concentrate include - 1. High density of cargo which might lead to damages in cargo holds and tank tops etc 2. Dry Shift of cargo (when the moisture content of the cargo is below TML) 3. Wet shift of cargo (when the moisture content of the cargo is above TML) 4. Some concentrate may also be liable to spontaneous combustion
    marinetales May 26, 2021
    Precautions for loading bagged cargoes - 1.Example of bagged cargoes include fishmeal, grain, beans, cocoa etc 2. Where the bags are stowed they should be on double dunnage, stacked either bag on bag or stowed half bag, as shown 3. The bag before being stowed shall be checked for wear and tear and cleanliness. Torn bag shall not be accepted. 4. Bags shall not be dragged as they can tear apart 5. Hooks shall not be used with paper bags and slings shall be used instead 6. Bags containing oil seed to be kept in cool place as they can cause combustion
    marinetales May 26, 2021
    1. Various commodities are used to handle steel plates including plate clamps on chain slings to electromagnetic expanding beams 2. The weight and size of this cargo makes it difficult and dangerous cargo to load and discharge and chain lashings are required in order to lash the steel plates once they are stowed 3. The cargo holds needs to be floored with dunnage.The damage to the tank top must be prevented by carefully lining the hold with protections , protecting the frames, sounding pipes, ballast tank pipes etc
    marinetales May 26, 2021
    1. The round shape of coil is a high risk to shifting of the cargo, when not properly secured 2. Normally stowed in double tier with the bottom coils on athwartships dunnage and wedged against athwartship movement, each coil being hard - up against the next 3. The main objective is to form a large immovable stow without any void spaces in between 4. End of stows are fenced with timber battens and locking coils together with the top tier of coils 5. The key Locking coils shall be identified and carefully lashed and chocked 6. The passage plan shall reflect a route that would be minimize the ship's rolling pattern wherever possible
    marinetales May 26, 2021
    Cooling down is a procedure to reduce the temperature of the cargo tanks prior loading in order to minimize thermal stress and excessive vaporization on gas tankers
    marinetales May 26, 2021
    Gassing up on gas tankers is a procedure to replace inert gas in the cargo tanks with the vapors of the cargo to be loaded. It is essential to ensure the correct operation of the re liquefaction plant and prevent pressure rise in the cargo tanks
    marinetales May 26, 2021
    As per the IMDG Code, EXCEPT for classes 1, 2, 6.2 and 7, Dangerous goods are divided into 3 packaging groups with respect to degree of danger they pose. A. Great danger - packaging group I B. Medium danger - packaging group II C. Minor danger - packaging group III
    marinetales May 26, 2021
    1. Dragger tubes are used to detect various other toxic gases present in the compartment 2. It works on the principle of chemical absorption of gas into chemical reagent present in the tube which changes the color of the reagent and helps in determining the ppm of the gas present 3. A sample of air is drawn into the detector tubes (opened at both ends). This tube has crystals of chemical reagent. One end of the tube is fit into the drager pump 4. Number of presses is given on the drager pump. In order to ensure that a constant air sample volume is drawn - a limiter chain is given 5. The graduation on tubes and its discoloration shows the percentage. of toxic gases present 6. Tubes are ordered as per the gas the user needs to measure. Eg of drager tubes are benzene, phosphine and hydrogen sulphide gases
    marinetales May 26, 2021
    1. The tankscope is used to measure the concentration of HC gases in an INERT atmosphere 2. The sensor element in this instrument is made of non-catalytic hot filament 3. This filament does not involve combustion of HC gases 4. It measures the rate of change of temperature of the hot filament due to the presence of the HC gas
    marinetales May 26, 2021
    1. Explosimeter is used for the detection of HC gases 2. Sample of air is taken and passed on one heated arm of a balanced wheatstone bridge 3. The current for the wheatstone bridge is provided by the dry cells 4. Combustible gases burn due to the heated filament and its temperature rises causes it to increase its resistance 5. The scale become unbalanced causing the meter to deflect which is proportional to the change of resistance 6. Explosimeter cannot be used in an INERT atmosphere because INERT atmosphere does not have Oxygen to support combustion 7. It does not show toxicity levels
    marinetales May 26, 2021
    Oxygen Analyzer is an equipment used to measure the oxygen content of a given atmosphere A sample of atmosphere is introduced into the sensor using an aspirator and is passed through a sensor which can be any of the three types - > Paramagnetic Sensor - this sensor uses the paramagnetic property of the Oxygen gas. A magnetic needle is suspended between the two magnets. The sample is passed over this magnet which gets deflected due to paramagnetic property of the oxygen. The opposing current is used to bring the needle back to its original position is calculated and is shown as the oxygen concentration > Electrolytic sensor - oxygen is allowed to pass in an electrolytic cell separated in a liquid which absorbs (from the sample) and the value of current is noted > Chemical absorption liquid - oxygen (from the sample) is absorbed in a liquid which causes change in volume and that volume is measured and read out as the percentage of oxygen present
    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
    Container ships are subjected to large angles of list due to rapid loading and discharging. Anti heeling tanks are provided to keep the list within control. It consists of set of two tanks located on the port and starboard side connected by athwartship pipelines. A sensor measures which side the list is and activates the pump to rapidly transfer the water to the higher side. It can also be set to activate on a predetermined value of list
    marinetales May 26, 2021
    According to grain code, a specially suitable compartment refers to a compartment which is constructed in a way so as to reduce the effect of any transverse shift of grain. It has at least two vertical or sloping longitudinal grain tight division coincident with hatch side girders
    marinetales May 26, 2021
    COW stands for Crude Oil Washing. It is the process in which the crude oil is used to wash the tanks while the cargo is being discharged which in turn increases the total output of the cargo. The main advantages of the COW are - 1. Reduces risk of pollution 2. Enhances the ship's cargo carrying capacity as lesser slops are carried 3. Better quantity of refined oil is discharged 4. Results in lesser time for tank cleaning during the voyage 5. Results in lesser cost of de sludging 6. Lesser corrosion in tanks due to non usage of SW 7. Better output of cargo discharged
    marinetales May 26, 2021
    The Contents of COW Manual includes - 1. Ship particulars 2. List of revised guidelines 3. Drawing and diagrams of the COW arrangements 4. Operation and Maintenance of COW 5. means of communication 6. Use of Inert Gas 7. List of personnel taking up the operation 8. Procedure for changing over from crude to product 9. COW checklists 10. Prevention against oil spill 11. Inspection and maintenance of COW equipments 12. Prevention against the static electricity 13. Guidelines regarding compliance with marpol annex 14. Typical COW machine programs