D1 mc s & m topic 3 loadline

D1MC Semester 1 / Survey & Maintenance / January 2009 /Topic 3 – LOADLINE 1 1

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International Convention on Load Line Rules 1966

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International Convention on Load Lines 1966

The first International Convention on Load Lines, adopted in 1930, was based on the principle of reserve buoyancy, although it was recognized then that the freeboard should also ensure adequate stability and avoid excessive stress on the ship's hull as a result of overloading.

In the 1966 Load Lines convention, adopted by IMO, provisions are made determining the freeboard of ships by subdivision and damage stability calculations.




• The Convention establishes limitations on the draught to which a ship on international voyages may be loaded, in the form of freeboards, which should ensure adequate stability and avoid excessive stress and the ship's hull as a result of overloading. It also deals with external weather tight and watertight integrity, and provisions are made for determining the freeboard of tankers by sub division and damage stability calculations.

• The regulations take into account the potential hazards present in the different zones and at different seasons. The technical annex contains several additional safety measures concerning doors, freeing ports, hatchways and other items. The main purpose of these measures is to ensure the watertight integrity of ship's hulls below the freeboard deck.




Application• Convention shall apply to ships engaged on

international voyages, except:

* warships;* new ships of less than 24 metres in length;* existing ships of less than 150 tons gross;* pleasure yachts not engaged in trade, and;* fishing vessels.




• CONDITIONS OF ASSIGNMENT OF FREEBOARD




Assignment of Freeboard• Procedure for Assignment of Freeboard

• The Merchant Shipping (Load Lines) rules came into operation on 21 July 1968 and contact the requirements for the surveying and assignment of freeboards to ships and the issue of Load Lines Certificates. The assigning authorities are the Government (Ministry of Transport, Malaysia) or Classification Societies such as Lloyd's Register of Shipping (LR), ABS etc.

• Application for the assignment of freeboards to a ship and for the issue of a Load Lines Certificate is made to an Assigning Authority by or on behalf of the owners. The application must be accompanied by plans, drawings and specifications that relate to the design and construction of the ship.




Assignment of FreeboardThe ship is then surveyed and the surveyor must ascertain that:

1. the construction of the ship shall be such that her structural strength will be sufficient for the free boards to be assigned

2. the stability in all probable loading conditions will be sufficient for the freeboards to be assigned; and

3. the construction of fittings and appliances for the protection of openings (sills, hatch coamings, closing appliances, side scuttles, freeing ports, scuppers, inlets and discharges), Arrangements for the protection of the crew such as guard rails (means of access), all comply with the specifications laid out in the rules.




Assignment of Freeboard

The surveyor provides the Assigning Authority with it report, which gives the results of the survey, and if that proves satisfactory freeboards are assigned to the ship. The owner is then given particulars of the freeboards assigned and the positions in which Load Lines, the Deck line and the load line mark to be actually marked. The owner is also given two copies of the surveyor's report and is issued with a 'Load Line Certificate’.




Load line Certificate• A Load Lines Certificates is valid for not more than 5 years after the

date of completion of the survey, subject to annual endorsements (Annual survey) within 3 months either way of each anniversary date of the certificate. This to ensure that alterations have not been made to the hull or superstructures which would affect the calculation determining the position of the Load Line and so as to ensure the maintenance in an effective condition of fittings and appliances for:

1. Protection of openings.

2. Guard rails

3. Freeing port, and

4. Means of access to crews’ quarters.




Load line Certificate

The authority may cancel a certificate if:

1. The ship does not comply with the conditions of assignment.

2. The structural strength of the ship is lowered to an unsafe standard (that makes the ship unsafe)

3. The information on which the freeboards were assigned was incorrect

4. A new certificate is issued

5. The ship ceases to be registered in the country (Malaysia)

6. The ship is not periodically inspected (the survey not done or defects not corrected).




Surveys and inspections

• (a) An initial survey before the ship is put in service, which shall include a complete inspection of its structure and equipment in so far as the ship is covered by the present Convention. The survey shall be such as to ensure that the arrangements, materials and scantlings fully comply with the requirements of the present Convention.

• (b) A renewal survey at intervals specified by the Administration but not exceeding five years, which shall be such as to ensure that the structure, equipment, arrangements, materials and scantlings fully comply with the requirements of the present Convention.




• (c) An annual survey within 3 months before or after each anniversary date of the certificate to ensure that:

(i) alterations have not been made to the hull or superstructures which would affect the calculations determining the position of the load line;

(ii) the fittings and appliances for the protection of openings, guard rails, freeing ports and means of access to crew's quarters are maintained in an effective condition;

(iii) the freeboard marks are correctly and permanently indicated;(iv) the information required to be supplied to Master is

provided.

Surveys and inspections




Definitions1) Length. The length (L) shall be taken as 96% of the total

length on a waterline at 85% of the least moulded depth measured from the top of the keel, or as the length from the foreside of the stem to the axis of the rudder stock on that waterline, if that be greater.

2) Perpendiculars. The forward and after perpendiculars shall be taken at the forward and after ends of the length (L). The forward perpendicular shall coincide with the foreside of the stem on the waterline on which the length is measured.

3) Amidships. Amidships is at the middle of the length (L).




4) Breadth. Unless expressly provided otherwise, the breadth (B) is the maximum breadth of the ship, measured amidships to the moulded line of the frame in a ship with a metal shell and to the outer surface of the hull in a ship with a shell of any other material.

5) Moulded depth. This is the vertical distance measured from the top of the keel to the top of the freeboard deck beam at side.




9) Freeboard deck. The freeboard deck is normally the uppermost complete deck exposed to weather and sea, which has permanent means of closing all openings in the weather part thereof, and below which all the openings in the sides of the ship are fitted with permanent means of watertight closing. In a ship having a discontinuous freeboard deck, the lowest line of the exposed deck and the continuation of that line parallel to the upper part of the deck is taken as the freeboard deck. A lower deck may be designated as the freeboard deck, provided it is a complete and permanent deck continuous in a fore and aft direction at least between the machinery space and peak bulkheads and continuous athwartships.

Definitions




When a lower deck is designated as the freeboard deck, that part of the hull which extends above the freeboard deck is treated as a superstructure so far as concerns the application of the conditions of assignment and the calculation of freeboard. It is from this deck that the freeboard is calculated.




Deck Line (Regulation 4)

• The deck line is a horizontal line 300 mm in length and 25 mm in breadth. It shall be marked amidships on each side of the ship, and its upper edge shall normally pass through the point where the continuation outwards of the upper surface of the freeboard deck intersects the outer surface of the shell plating




However, the deck line may be placed with reference to another fixed point on the ship on condition that the freeboard is correspondingly corrected and that the reference point location and the identification of the freeboard deck isclearly indicated on the International Load Line Certificate.

This is typical in the case of a ship having a radiused sheerstrake (rounded gunwale)




Regulation 5 Load Line Mark

The Load Line Mark shall consist of a ring 300 mm in outside diameter and 25 mm wide which is intersected by a horizontal line 450 mm in length and 25 mm in breadth, the upper edge of which passes through the centre of the ring. The centre of the ring shall be placed amidships and at a distance equal to the assigned summer freeboard measured vertically below the upper edge of the deck line.




Load Line Mark

300 mm

450 mm

25 mm







If timber freeboards are assigned, the timber load lines are marked in addition to the ordinary load lines as shown in figure:




Minimum free boards are assigned so that a vessel remain seaworthy when loaded and to provide reserve buoyancy so that:

1. The vessel will not be in danger of foundering in heavy seas

2. In the event of major damage the vessel will still remain afloat or will sink slowly enough so as to enable the crew to get clear

International convention has divided the world into zones the least dangerous 'Tropical' zone and the most dangerous 'winter, North Atlantic'. The winter in the North Atlantic is notoriously rugged and so that is where the ship needs the greatest amount of intact space above the waterline.




Load line Zones

• The seasonal zones, areas and periods that determine the appropriate load line in a particular sea area at a given time of year are by way of the chart.

• The Tropical, Summer and Winter freeboard zones are based upon the following weather criteria:

• Summer Zones – Regions where not more than 10% of wind speeds exceed force 8 Beaufort (34 knots).

• Tropical Zones – Regions where not more than 1% of wind speeds exceed force 8 Beaufort (34 knots) and not more than one tropical storm in a ten-year period occurs in an area of 5º latitude/longitude square in any one separate calendar month.

• Winter Zones – Are all other regions.




• Tropical Zone: - The permanent tropical is colored 'green' on the zone chart, the boundary north and south of it may be seen on the zone chart. The ships are allowed to load up to tropical Load line when they are in this zone through out the year.

• Seasonal Tropical or Summer Zones or Areas: - these zone or areas are found on the zone chart with 'Light Green colors', which lies between the permanent tropical, and summer zones. The ships loading in these areas are required to load according to the" season. Seasonal period for this is as:




Seasonal Tropical or Summer Zones

• North Atlantic Tropical : 1st November - l5th July

• North Atlantic Summer : 16th.July- 3rd October

• Arabian Sea Tropical : 1st September – 3rd May

• Arabian Sea Summer : 01st June - 3Ist August

• Bay of Bengal Tropical : 01st December - 30th.April

• Bay of Bengal Summer : 01st May - 30th November

• China. Sea Tropical : 21st Jan – 30th April

• China Sea Summer : 01st May – 20th January

• South Indian Ocean North Pacific & South Pacific Tropical: 01st April – 30th November

• South Indian Ocean North Pacific & South Pacific Summer. 01stDecember – 31st March




• It is a criminal offence for the Master and/or shipowner to allow a vessel to be operated in a zone, when in the upright condition, the relevant amidships zone load line would be below the still load waterline. Such an action would immediately invalidate all Classification Society and Load Line certification and will lead to criminal prosecution.




Regulation 10 Information to be supplied to the master

(1) The master of every new ship shall be supplied with sufficient information, in an approved form, to enable him to arrange for the loading and ballasting of his ship in such a way as to avoid the creation of any unacceptable stresses in the ship's structure, provided that this requirement need not apply to any particular length, design or class of ship where the Administration considers it to be unnecessary.

(2) The master of every new ship which is not already provided with stability information under an international convention for the safety of life at sea in force shall be supplied with sufficient information in an approved form to give him guidance as to the stability of the ship under varying conditions of service, and a copy shall be furnished to the Administration.




Loadline Survey




Preparation for loadline survey

1) Check that all access openings at ends of enclosed structures are in good conditions. All dogs, clamps and hinges to be free and well greased. All gaskets and water-tight 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 and securing of portable beams4) If portable wooden hatch covers are used check that they are

in good condition5) If tarpaulins are used at least two should be provided for

each hatch and in good condition





6) Inspect all machinery space opening on exposed deck

7) Check that any manholes and flush scuttles are capable of being made watertight

8) Check that all ventilator openings are provided with efficient weather tight closing appliance

9) All air pipe should be provided with satisfactory means for closing and opening

10) Inspect any cargo ports below the freeboard deck and ensure that all of them are watertight





11) Ensure that non return valves on overboard valves are operating in a satisfactory manner

12) Side scuttles and openings below the freeboard deck must have efficient internal watertight deadlights

13) Check that all freeing ports are in satisfactory conditions

14) All guard-rails and bulwarks should be satisfactory condition

15) De rust and paint the deck line, loadline marks, load line and the draught marks




Quick Info

Deadlight - steel, hinged cover to protect the porthole's glass in heavy weather or to prevent lights inside the ship from showing outside; it can be mechanically secured by screws and nuts

Scuttles - small opening in a ship's deck, side or compartment which can be closed by a shutter when required

Freeing ports - openings cut in the bulwark to free the deck of water

Bulwark - shell plating about one metre in height built around the outboard edge of upper deck from forecastle to poop to protect men and cargo against rough seas

Gunwale - the upper edge of the side of a small ship or boat, or upper edge of bulwarks in bigger ship




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D1 mc s & m topic 3 loadline

Travel

survey maintenance

d1mc semester

load lines convention

freeboard of ships

load line rules

load line mark

assignment of freeboards

freeboard deck