Q. With the aid of a demonstrating sketch explain the difference between International load line marking and subdivision load line marking. How will you prepare your ship for renewal Load line survey?
The Plimsoll Line is the line where the hull of the vessel meets the surface of the water. Generally, it is also the name of a special marking, also called as the International Load Line (ILL) or water line (positioned amidships), that indicates the draft of the vessel & the legal limit to which a vessel may be loaded for the specific water types & temperatures in order to safely maintain the buoyancy, particularly with regard to the hazard of the waves that may arise.
Temperature affects the level because warm water allows less buoyancy, being less dense than the cold water, as does salinity because fresh water is less dense than the salty seawater.
For vessels with the displacement hulls, the hull speed is found out by, amongst other things, the waterline length. In a sailing boat, the waterline length can change significantly when the boat heels, & can dynamically affect the speed of boat.
The purpose of the load line is to assure that a vessel has sufficient freeboard (the height from the water line to the main deck) & thus sufficient reserve buoyancy, as seen from the outside.
The original “Plimsoll mark” was a circle with a horizontal line through it to show the maximum draft of a vessel. Additional marks have been added over the years, allowing for the different water densities & expected sea conditions.
The letters on the load line marks have the following meaning :
TF – Tropical fresh water
F – Fresh water
T – Tropical sea water
S – Summer temperature sea water
W – Winter temperature seawater
WNA – Winter North Atlantic
Subdivision load line marks
Passenger ships having spaces which are used for the accommodation of the passengers & the carriage of the cargo alternatively may have one or more additional load line marks corresponding to the subdivision drafts approved for the alternative conditions. These marks show P1 for the principal passenger condition, & P2, P3, etc ., for alternative conditions, however in no case shall any subdivision load line mark be placed above the deepest load line in the salt water
Preparation for the load line survey
1. Check that all access openings of the enclosed structures are in good conditions. All dogs, clamps & hinges to be free & well greased. All gaskets & watertight seals should be crack free. Ensure that the doors open from both sides.
2. Check all cargo hatches and access to holds for weather tightness.
3. Check the efficiency & securing of the portable beams.
4. If portable wooden hatch covers are used check that they are in good condition
5. If tarpaulins are used at least 2 should be provided for each hatch & in good condition.
6. Inspect all machinery space opening on the exposed deck
7. Check that any manholes & flush scuttles are capable of being made watertight
8. Check that all ventilator openings are provided with efficient weathertight closing appliance
9. All airpipe should be provided with satisfactory means for closing & opening
10. Inspect any cargo ports below the freeboard deck & assure that all of them are watertight
11. Assure that non return valves on overboard valves are operating in a satisfactory manner
12. Side scuttles & openings below the freeboard deck must have efficient internal watertight deadlights
13. Check that all freeing ports are in the satisfactory conditions
14. All guard-rails & bulwarks should be satisfactory condition
15. Derust & paint the deck line, load line marks, load line & the draught marks.
Q. a) What are the essential elements of preventive maintenance on board ships?
b) Analyze the link between statutory & classification survey of ship machinery & equipment with respect to routine maintenance and how it is effectively merged in ships safety management system under the ISM code.
The elements of planned preventive maintenance are:-
- Safety, quality and efficiency
- Standardized maintenance scheme for the fleet
- Phased and balanced overhaul schedules
- Prevention or at least greatly reduced, breakdown of equipment
- Optimization use of man power, machinery and money
- Proper control of the spare parts & stores inventory on board
Planned preventive maintenance can be effectively applied on ships in the following areas:
A) Main Engine:
Every 500 hours
1) Clean turbocharger air filter
Every 1000 hours
1) Clean under piston and scavenge spaces change scavenge valves
2) Inspect piston, piston rings and liner through scavenge ports. Check if cylinder is flowing into the liner.
3) Carryout Crank case and cam case inspection
4) Do function test of all alarms/cut outs
Every 2000 hours
1) Send L.O. samples for analysis
2) Check main and cross head bearing clearance
3) Grease M/E fuel links
Every 4000 hours
1) Check overhead fuel valves
2) Overhaul starting air valves and exhaust valves
3) Check tightness of cylinder head units
4) Change governor oil.
5) Clean air cooler
Every 8000 hours
1) Decarbonisation of cylinders
2) Overhaul automatic starting air valve
3) Overhaul exhaust valve hydraulic actuators
4) Check/adjust fuel pump timing
5) Overhaul fuel pump
6) Test cylinder head relief valves
7) Over haul turbo charges
8) Check/adjust tightness of holding down bolts
9) Check thrust bearing clearance
Every 32000 hours
1) Replace fuel pump plunger and barrel
B). Statuarory & classification survey of ship machinery & equipment provides the link & effectively merged in ship safety management under ism code. Ism code element 10 describes maintenance of the ship and equipment.
The procedures should be established which ensure that maintenance; repairs and relevant surveys are carried out in a planned, safe and timely manner with the provisions of relevant rules and regulations.
Inspections, reporting maintenance non-conformities, corrective action, records-while original signed reports and certificates are required by flag administrations or classification society to keep on board, copies of maintenance records, survey reports and certificates covering international, national and classification rules and regulations should be held ashore by a responsible person. records must be retained onboard and ashore for a prescribed period.
Critical equipment & systems to be identified appropriate tests & other procedures should be developed to assure functional reliability or the use of alternative arrangements in the event of the sudden failure.