Onderwerp: Bezoek-historie

Nr. 33 Guidelines for submersible pontoons handling cargo at sea
Geldigheid:01-04-2000 t/m 31-12-2004Status: Was geldig

Dit onderwerp bevat de volgende rubrieken.


1. Application

The requirernents are applicable during Ioading and unloading of submersible seagoing pontoons which, under favourable environrnental circurnstances, are handling cargo outside the protective circumstances of a harbour. Subrnersiblepontoons are characterisedby the possibilityof carrying deck cargo, which is Ioaded and unloadedby submersion of the freeboard deck(float on - float off procedure).

2. Load lines

2.1 Generally the provisions of the International Convention on LoadLines 1966 are applicable. During cargo handling the Load Line Mark may become submerged and on account of this an International Load Line Exemption Certificate in accordance with Article 6(2) of the Convention shall be issued.

2.2 During the submersion procedure the Iower edge of non-watertight openings shall have a distance above the waterline of 1 m or a distance corresponding to a heeling angle of 5 degrees, whichever is the greater distance.

2.3 Openings which may become immersed during the submersion procedure shall have closing appliancesto be closed effectively watertight and having the same strength as the unpierced bulkhead.

3. Watertight subdivision

The water tight subdivision shalI be in conformity with the rules and regulations of a recognized organisation.

4. Damage stability

Because of an increased probability of minor damage during cargo handling submersible pontoons shall be able to withstand flooding during all stages of submersion due to a damage extent as specified in 4.1, a permeability as specified in 4.2 and taking info account the survival criteria as specified in 4.3.

4.1 Fo rthe purpose of damage stability calculations a one-compartment standard shall be assurned with a damage length of 5 m, which implies that watertight bulkheads may be considered to remain intact provided that the distance between adjacent bulkheads exceeds 5 m. The damage penetration shall be assumedto be equal to 0.76 m and the vertical extent of damage is assurned to be from the exposed deck upwards without limit.
Damage cases to be considered are:

4.1.1 AII sides of casings fitted on the exposed deck.

4.1.2 Superstructure bulkheads adjacent to the exposed deck,

4.1.3 The sides of a superstructure over a distance of 2.5m measured from the front bulkhead adjacent to the exposed deck.

4.2 The permeability µof adamaged cornpartment shall be assumed to be 0.95 except for(full) ballast tanks(in whichcase µ=0).

4.3 The damage stability criteria are as follows:

4.3.1 The final water line after flooding is below the Iower edge of any non- watertight opening through which progressive flooding may take place.

4.3.2 The angle of heel after flooding shall hot exceed 15 degrees.

4.3.3 The residual stability in the final condition shall be regarded as satisfactory if the righting lever curve has a minimum range of 20 degrees beyond the position of equilibrium with a maximum righting lever of at least 0.1 rn within this range and non-weathertight openings are not submerged within this range.

4.3.4 The concerning recognized organisation shall be satisfied that the stability is sufficient during intermediate stages of flooding.

4.4 The flooding of any damaged compartment shall not result in rendering the pontoon in operative, completely or partially.

4.5 In addition to damage stability calculations it is recommended to provide for preventive meassures by fitting an external protection by means of an effective fendering system.

5. Intact stability

5.1 If during the submersion procedure no bottom contact occurs the intact stability of a submersible pontoon shall comply during all intermediate conditions with the following requirements:
B5.1.1 Heeling angle less than 5 degrees. 5.1.2 Range of stability not less than 20 degrees. 5.1.3 Area under the righting lever curvenot less than 0.075 mrad. 5.2 If during the submersion procedure bottom contact occurs the intact stability of a submersible pontoon shall comply during all intermediate conditions with the following equirement: 5.2.1 The metacentric height shall, after correction for free surface effects and occuring bottom reaction force (to be considered as a point contact), be not less than.0.3 m. The basic idea for distinguishing in stability criteria for various submersion procedures is whether rather or not a discontinuity in the stability properties will occur by an abrupt reduction of the waterline area of cargo and pontoon. 6. StrengthThe strength, taking into account the maximum attainable submerged draught, shall be in conformity with the rules and regulations of a recognized organisation. 7. Stabillty Informartion7.1 The stability information to be used on board shall be determined for each separate project of Ioading taking info account the actual Ioading condition, 7.2 The stability information to be submitted to the Administration shall cover the following (hypothetical) Ioading conditions: 7.2.1 Cargo weight is equal to the carrying capacity of the pontoon and is assumed to be uniformly distributed over the full length and breadth of the exposed cargo deck. The calculations shall be carded out for various positions of the height of the centre of gravity (and with that corresponding height of the deck cargo) and the trim value as a parameter. 7.2.2 As 7.2.1,however with an assumred clearance of 1 m between the exposed deck and the cargo. 7.2.3 As 7.2.1, however with the cargo uniformly distributed over the middle most 50 percent of the length of the exposed deck. 7.2.4 As 7.2.1, however with the cargo concentrated halfway the length of the exposed deck and having no buoyancy at all. 7.2.5 Pontoon without cargo and the tti value as a parameter. 8. Mechanical aspects8.1 The arrangement of the machinery installation shall be such that the power supply necessary for the submersion procedure during cargo handling is secured. 8.2 The arrangements for hydraulic or pneumatic controlled valves shall be to the satisfaction of the concerning recognized organisation. 9. General9.1 A plan giving particulars concerning the method of draught indication shall be submitted to the concerning recognized organisation for approval. 9.2 It is recommended for submersible pontoons experiencing bottomcontact to carry out a survey of the (sea)bottom prior to the submersion procedure in order to obtain information on the character of these oil and to locaIise possible obstacles present. 9.3 Since it is impossible at this stage to establish a uniform criterin in respect of a Iimitation of the environmental conditions (wind, waves and current) the decision on carrying out the submersion procedure tests on the judgement of the operator accepting responsibility.

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