NVIC 05-83: Unified interpretations of Load Lines Convention

NAVIGATION AND VESSEL INSPECTION CIRCULAR NO. 5-83 Subj: Unified Interpretations of the International Convention on Load Lines, 1966 28 APR 1983

Unified Interpretation of the International Convention on the Load Lines, 1986 — PURPOSE. The purpose of this Circular is to issue the three sets of

Unified Interpretations of the International Convention on Load Lines, 1966 that have been approved by the Maritime Safety Committee of the International Maritime Organization (IMO).

Unified Interpretation of the International Convention on the Load Lines, 1986 — DIRECTIVES AFFECTED. This Circular cancels and supersedes NVIC 1-77.

DIRECTIVES AFFECTED. This Circular cancels and supersedes NVIC 1-77.

Unified Interpretation of the International Convention on the Load Lines, 1986 — ACTION. Enclosures (1) through (3) may be used as an aid in

interpreting specific provisions of the 1966 International Load Line Convention. Only those interpretations approved by the Maritime Safety Committee of IMO are contained in the enclosures. Encl: (1) LL.3/Circ.20 "List of Unified Interpretations issued by the International Association of Classification Societies in 1972" dated 26 May 1976.

(2) LL.3/Circ.22 "List of Unified Interpretations" dated 19 May 1977.

(3) LL.3/Circ.42 "List of Unified Interpretations" dated 13 April 1982.

DISTRIBUTION - SDL No. 117 [DISTRIBUTION TABLE - columns labeled A through Z with various numerical entries] NON-STANDARD DISTRIBUTION: (See page 2) NAVIGATION AND VESSEL INSPECTION CIRCULAR NO. 5-83 28 APR 1983 NON-STANDARD DISTRIBUTION: C:e Baltimore (45); Alameda (40); Port Arthur, Honolulu (35); Miami, Mobile, Long Beach (25); Norfolk, Jacksonville, Portland OR (20); Boston, Portland ME, Charleston, Anchorage (15); Cincinnati, Louisville, Memphis, Nashville, Paducah, Pittsburgh, St Louis, Savannah, San Juan, Tampa, Galveston, Buffalo, Chicago, Detroit, Duluth, Milwaukee, San Diego, Juneau, Valdez (10); Providence, Huntington, St Paul, Wilmington, Corpus Christi, Cleveland, Toledo (5).

C:m New Orleans (140); New York (70); Seattle, Philadelphia (35); Houston (25); St Ignace (5); Sturgeon Bay (4).

D:l CG Liaison Officer MILSEALIFTCOMD M-60 STRAT MOB only (1) ZTC-68 INTER-GOVERNMENTAL MARITIME CONSULTATIVE ORGANIZATION 101-104 PICCADILLY, LONDON, W1V OAE Telegram: INMARCOR-LONDON,W.1 Telephone: 01-499 9040 Ref.

T4/1.03 Enclosure (3) to NVIC LL.3/Circ.42 13 April 1982 28 APR 1983 IMCO INTERNATIONAL CONVENTION ON LOAD LINES, 1966 List of Unified Interpretations The Secretary-General has the honour to refer to LL.3/Circ.20 and LL.3/Circ.22 with which unified interpretations of the International Convention on Load Lines, 1966 were circulated to Contracting Governments.

The Secretary-General would like to inform Contracting Governments that the Maritime Safety Committee at its forty-sixth session approved a third set of unified interpretations to the International Convention on Load Lines, 1966 which is attached hereto.

Contracting Governments of the International Convention on Load Lines, 1966 are invited to take note of these additional interpretations with a view to their application.

The Secretary-General would also like to state that the Maritime Safety Committee at its forty-sixth session also urged Contracting Governments to ratify the Amendments adopted by the Assembly in: - October 1971 by resolution A.231(VII); - November 1975 by resolution A.319(IX); and - November 1979 by resolution A.411(XI).

ANNEX VIII INTERNATIONAL CONVENTION ON LOAD LINES, 1966 LIST OF THOSE UNIFIED INTERPRETATIONS, ISSUED BY IACS IN 1972, ACCEPTED BY THE MARITIME SAFETY COMMITTEE Interpretation LL. 1 Application (Article 4(4)) Even where the increase in draught is only of the order of 1 in. or 2 in. there should be no relaxation from the condition that existing ships comply with all the requirements.

Interpretation LL. 2 Depth for Freeboard (Regulation 3(6)) The correction for thickness of sheathing on the exposed freeboard deck, T(L-S), is applicable only when the deck is completely sheathed between superstructures.

In other cases the correction should be T x l where l = length of sheathed area which extends from side to side.

Only wood sheathing should be considered.

Interpretation LL. 3 Superstructure (Regulation 3(10)(b)) A bridge or poop shall not be regarded as enclosed unless access is provided for the crew starting from any point on the uppermost complete exposed deck or higher to reach machinery and other working spaces inside these superstructures by alternative means which are available at all times when bullkhead openings are closed.

Interpretation LL. 4 Details of Marking (Regulation 8) "Permanently marked" is considered to include welding of the marks on the sides of the ship provided the usual precautions as to material, electrodes etc. are observed.

Interpretation LL. 5 Doors (Regulation 12)

(a) Doors should generally open outwards to provide additional security against the impact of the sea. Doors which open inwards are to be especially approved.

(b) Portable sills should be avoided. However, in order to facilitate the loading/unloading of heavy spare parts or similar portable sills may be fitted on the following conditions:

(1) They must be installed before the ship leaves port.

(2) Sills are to be gasketed and fastened by closely spaced through bolts.

(3) Whenever the sills are replaced after removal, the weathertightness of the sills and the related doors must be verified by hose testing. The dates of removal, replacing and hose testing shall be recorded in the ship's log book. Interpretation LL. 6 Hatchweys closed by weathertight covers of steel or other equivalent material Fitted with Gaskets and Clamping Devices (Regulations 16 and 27(7)(c))- Regulation 16: Where hatchweys are fitted with coanings of standard height, no extra strengthening (beyond what is required in the Load Line Convention) shall be required for covers loaded with cargo, even if dense cargo, provided the load does not exceed 1.75 tons/m² (in position 1). Regulation 27(7)(c): No extra strengthening is recommended for hatchway covers on vessels which are assigned freeboards less than those based on Table B, except for flush hatchway covers which are fitted on the freeboard deck forward of the quarter length, in which case the section modulus and the moment of inertia shall be increased 15% over that required by Regulation 16. Interpretation LL. 7 Machinery Space Openings (Regulation 17(1)) Where casings are not protected by other structures double doors should be required for ships assigned freeboards less than those based on Table B. An inner sill of 230 mm in conjunction with the outer sill of 600 mm is recommended. Interpretation LL. 8 Miscellaneous Openings in Freeboard and Superstructure Decks

(Regulation 18(2) and 18(3)) Regulation 18(2): Only those doorways in deckhouses leading to or giving access to companionways leading below, need to be fitted with doors in accordance with Regulation 12. Alternatively, if stairways within a deckhouse are enclosed within properly constructed companionways fitted with doors complying with Regulation 12, then the external doors need not be weathertight. Where an opening in a superstructure deck or in the top of a deckhouse on the freeboard deck which gives access to space below the freeboard deck or to a space within an enclosed superstructure and is protected by a deckhouse, then it is considered that only those side scuttles fitted in spaces which give direct access to an open stairway need be fitted with deadlights in accordance with Regulation 23. A cabin is considered to provide adequate protection against the minimal amount of water which will enter through a broken side scuttle glass fitted on the second tier. Regulation 18(3): In the application of Regulation 18 it is understood that:

(a) where access is provided from the deck above as an alternative to access from the freeboard deck in accordance with Regulation 3(10)(b) then the height of sills into a bridge or poop should be 380 mm. The same consideration should apply to deckhouses on the freeboard deck.

(b) where access is not provided from above, the height of the sills to doorways in a poop bridge or deckhouse on the freeboard deck should be 600 mm.

(c) where the closing appliances of access openings in superstructures and deckhouses are not in accordance with Regulation 12, interior deck openings are to be considered exposed, i.e. situated in the open deck.

Interpretation LL. 10 Air Pipes (Regulation 20) For ships assigned timber freeboards the air pipes should be provided with automatic closing appliances.

Interpretation LL. 11 Scuppers, Inlets and Discharges (Regulation 22(1)) It is considered that an acceptable equivalent to one automatic non-return valve with a positive means of closing from a position above the freeboard deck would be one automatic non-return valve and one shore valve controlled from above the freeboard deck.

Where two automatic non-return valves are required, the inboard valve must always be accessible under service conditions, i.e. the inboard valve should be above the level of the typical load water line.

If this is not practicable, then, provided a locally controlled slice valve is interposed between the two automatic non-return valves, the inboard valve need not be fitted above the LWL.

Where sanitary discharges and scuppers lead overboard through the shell in way of manned machinery spaces, the fitting to shell of a locally operated positive closing valve together with a non-return valve inboard, is considered to provide protection equivalent to the requirements of Regulation 22(1).

It is considered that the requirements of Regulation 22(1) for non-return valves are applicable only to those discharges which remain open during the normal operation of a vessel.

For discharges which must necessarily be closed at sea such as gravity drains from topside ballast tanks, a single screw down valve operated from the deck is considered to provide efficient protection.

Interpretation LL. 12 Side Scuttles (Regulation 23) For those vessels where the freeboard is reduced on account of subdivision characteristics, side scuttles fitted outside the space considered flooded and which are below the final waterline shall be of the non-opening type.

Interpretation LL. 13 Freeing Ports (Regulation 24(1) and 24(5)) Regulation 24(1): On a flush deck ship with a substantial deckhouse amidships it is considered that the deckhouse provided sufficient break to form two wells and that each could be given the required freeing port area based upon the length of the "well".

It would not then be allowed to base the area upon 0.7L.

In defining a substantial deckhouse it is suggested that the breadth of the deckhouse should be at least 80% of the beam of the vessel, and that the passageways along the side of the ship should not exceed 1.5 m (4.9 ft.) in width.

Where a screen bulkhead is fitted completely across the vessel, at the forward end of a midship deckhouse, this would effectively divide the exposed deck into wells and no limitation on the breadth of the deckhouse is considered necessary in this case.

It is considered that wells on raised quarter decks should be treated as previously, i.e. as being on freeboard decks.

Regulation 24(5): With zero or little sheer on the exposed freeboard deck or an exposed superstructure deck it is considered that the freeing port area should be spread along the length of the well.

Interpretation LL. 14 Protection of the Crew (Regulation 25(2)) A guard rail shall also be required for first tier deckhouses and for superstructures' ends.

Interpretation LL. 15 Length of Superstructure (Regulation 34(1) and 34(2)) Regulation 34(1): Where a superstructure bulkhead is recessed, the effective length of the superstructure shall be reduced by an amount equivalent in area to the area of the recess related to the breadth of the ship at the mid-length of the recess.

Where the recess is unsymmetrical about the centre line, the largest portion of the recess shall be considered as applying to both sides of the ship.

It is considered that such a recess need not be decked over.

Regulation 34(2): Where there is an extension to a superstructure, which extension has a breadth on each side of the centre line of at least 30% of the breadth of the ship, the effective length of the superstructure may be increased by considering an equivalent superstructure bulkhead in the form of a parabola.

This parabola should extend from the extension at the centre line and pass through the junction of the actual superstructure bulkhead with the sides of the extension and extend to the sides of the ship.

This parabola should be completely contained within the boundary of the superstructure and its extensions.

Interpretation LL. 16 Sheer (Regulation 38) Where the height of a superstructure is less than standard, paragraph 12 may be applied except that the superstructure deck shall be not less than the minimum height of the superstructure above the virtual sheer curve at any point.

For this purpose "y" shall be taken as the difference between the actual and minimum height of the superstructure at the end of sheer.

Interpretation LL. 18 Freeboard Tables (Regulation 28)

(1) Type "A" ships

(a) Freeboards for Type "A" ships with lengths of between 365 m and 400 m shall be determined by the following formula: f = 221 + 16.10L - 0.02L² where f is the freeboard in cm L is the length as defined in Regulation 3(1).

(b) Freeboards for Type "A" ships with lengths of 400 m and above shall be the constant value, 3460 cm.

(2) Type "B" ships

(a) Freeboards for Type "B" ships with lengths between 365 m and 400 m shall be determined by the following formula: f = -587 + 25L - 0.0188L² where f is the freeboard in cm L is the length as defined in Regulation 3(1).

(b) Freeboards for Type "B" ships with lengths of 400 m and above shall be the constant value, 5605 cm. Interpretation LL. 19 Form of Certificates (Article 16) It is recommended that the model form of certificates given in Annex III of the Load Line Convention should be strictly adhered to and any deviations from this pattern should be avoided. Interpretation LL. 20 Hatch beams and cover stiffeners of variable cross section

(Regulations 15(4), 15(5), 15(6), 15(7) and 16) To avoid stresses and deflections exceeding those given in the above Regulations along construction elements of variable cross section, the required section modulus calculated as for construction elements of constant cross section is to be increased by a factor K expressed by: K = 1 + (3.2 α - 7 - 0.8)/(7γ + 0.4) where α = l₁/l₀, γ = W₁/W₀ The value of factor K obtained by the formula is to be not less than unity. l₁, l₀, W₁ and W₀ are indicated on the sketch below: [FIGURE — no transcribable text] The moment of inertia is likewise to be increased by the factor C expressed by: C = 1 + 8 α³ · (l - β)/(0.2 + 3√β) where α = l₁/l₀, β = l₁/l₀ The value of factor C obtained by the formula is to be not less than unity. l₁ and l₀ are indicated on the sketch above. The use of the above formulae is limited to the determination of the strength of hatch beams and covers in which abrupt changes in the section of the face of hatch beams and covers in which abrupt changes in the section of the face material do not occur along the length of the beam or cover. Interpretation LL. 21 Cargo ports or similar openings below the uppermost load line (Regulation 21(2)) It is recommended that cargo ports or similar openings may be accepted submerged provided the safety of the ship is in no way impaired. It is considered that the fitting of a second door of equivalent strength and watertightness is one acceptable arrangement. In that case a leakage detection device should be provided in the compartment between the two doors. Further, drainage of this compartment to the bilges controlled by an easily accessible screw down valve, should be arranged. The outer door should preferably open outwards. Interpretation LL. 22 Position of the inboard end of discharges when a timber freeboard is assigned

(Regulation 22(1)) It is considered that the position of the inboard end of discharges should be related to the timber summer load waterline when a timber freeboard is assigned.

Interpretation LL. 23 Freeing arrangement (Regulations 26(5), 27(7) and 36(1)(e)) Regulation 27(7): Freeing arrangements on ships having reduced B freeboard assigned and fitted with bulwarks on the freeboard deck For Type "B" ships with freeboards reduced by not more than 60% of the difference between B and L tables there shall be freeing port area in the lower part of the bulwarks equal to at least 25% of the total area of the bulwarks.

The upper edge of the sheer strike shall be kept as low as possible.

Regulations 26(5) and 36(1)(e): Freeing arrangements for Type "A" ships and Type "B" ships with trunks It is considered that a freeing port area, in the lower part of the bulwark, of 33% of the total area of the bulwarks provides the "other effective freeing arrangements" mentioned in Regulation 26(5), and may be considered equivalent to the 50% open rails in way of trunks required by Regulation 36(1)(e).

Interpretation LL. 24 Negative depth correction (Regulation 31(3)) When the height of a superstructure, raised quarter deck or trunk is less than the corresponding standard height, it is recommended that the calculated reduction be corrected in the ratio of the height of the actual superstructure, raised quarter deck or trunk, to the applicable standard height as defined in Regulation 33.

Interpretation LL. 25 Effective length of raised quarter deck (Regulation 35(4)) It is recommended that the maximum effective length of 0.6L of a raised quarter deck which is stipulated by Regulation 35(4), is to be measured from the after perpendicular even where a poop is fitted in conjunction with the raised quarter deck.

Interpretation LL. 26 Continuous hatchways as trunk (Regulation 36) It is recommended that continuous hatchways may be treated as a trunk in the freeboard computation provided Regulation 36 is complied with in all respects.

The trunk deck stringer referred to in Regulation 36(1)(b) may be fitted outboard of the trunk side bulkhead in association with the following:

(1) The stringer so formed is to provide a clear walkway of at least 450 cm in width on each side of the ship.

(2) The stringer is to be of solid plate efficiently supported and stiffened.

(3) The stringer is to be as high above the freeboard deck as practicable and not more than 600 mm below the top of the hatchway coanings.

(4) Hatch cover securing appliances are to be accessible from the stringer or walkway.

(5) The breadth of the trunk is to be measured between the trunk side bulkheads.

(6) Regulation 36 is to be complied with in all other respects. Interpretation LL. 27 Less than standard height hatch coanings on trunks of less than standard height

(Regulation 36(4)) In the case where the trunk height is less than standard and the trunk hatch coanings are also of less than standard height, or omitted entirely, doubt may arise whether the trunk hatchways are located in position 1 or position 2 and, consequently, about the reduction to be made in the actual trunk height. It is considered that in these cases the reduction from the actual height of trunk on account of insufficient hatch coaning height shall be taken as the difference between 600 cm and the actual height of coaning, or 600 cm if no hatch coanings are fitted. Reduction in the actual height of trunk shall not be required in cases where only small hatches with less than standard height are fitted in the trunk dock for which dispensation from the requirement of standard coaning height may be given. Interpretation LL. 29 Sheer credit for superimposed superstructure (Regulation 38(5) and 38(12)) In applying Regulation 38(5) (sheer on complete superstructure ship), where there is an enclosed poop or forecastle superimposed on a complete superstructure, sheer credit shall be allowed for such poop or forecastle according to the method of Regulation 38(12), except that "y" is to be the actual height of the poop or forecastle at the end ordinate. Interpretation LL. 30 Sheer allowance for excess height of superstructure

(Regulation 38(7) and 38(12)) As Regulation 38(7) and (12) does not refer to a raised quarter deck it is recommended that credit under this paragraph be given for this type of superstructure only when the height of the raised quarter deck is greater than the standard height of "other superstructures" as defined in Regulation 33, and only for the amount by which the actual height of the raised quarter deck exceeds that standard height. Interpretation LL. 31 Deduction for excess sheer (Regulation 38(15)) Since no stipulation is made as to the height of the superstructure referred to in Regulation 38(15), it is recommended that the height of this superstructure shall be related to its standard height. When the height of the superstructure or raised quarter deck is less than standard, the reduction shall be in the ratio of the actual to the standard height thereof. Interpretation LL. 32 Special requirements for vehicle ferries, Ro-Ro ships and other ships of similar type

(a) Stern, bow and side doors of large dimensions, when manual devices would not be readily accessible, are to be normally secured by means of power systems. Alternative means of securing are also to be provided for emergency use in case of failure of the power systems. Interpretation LL. 33 Timber freeboards for ships having reduced Type "B" freeboards assigned It is understood that some Administrations accept that timber freeboards may be assigned to ships with reduced Type "B" freeboards, provided the timber freeboards are calculated on the basis of the ordinary Type "B" freeboard. It is recommended that Regulation 45(2) and (3) is interpreted or, if necessary, amended such that the Timber Winter mark and/or the Timber Winter North Atlantic mark are placed at the same level as the reduced Type "B" Winter mark when the computed Timber Winter mark and/or the computed Timber Winter North Atlantic mark fall below the reduced Type "B" Winter mark. Interpretation LL. 34 Freeboard for lighters and barges (Regulation 27(11)) In applying Regulation 27(11) to deck cargo barges it is recommended that only Type "B" freeboard be assigned, even if the barges possess the same integrity of exposed decks and equivalent safety against flooding as normal tank barges. This view is taken as a result of the consideration that Type "L" freeboard can be assigned only to liquid cargo barges. It is further concluded that dock cargo can be carried only on barges to which Type "B" freeboard is assigned. INTER-GOVERNMENTAL MARITIME CONSULTATIVE ORGANIZATION 101-104 PICCADILLY, LONDON, W1V OAE Telegram: INMARCOR-LONDON,W.1 Telephone: 01-499 9040 Ref: T4/1.03