Onderwerp: Bezoek-historie

NtS 279/1992 Intact stability of ships, not being offshore support vessels or unmanned pontoons
Geldigheid:13-02-1992 t/m Status: Geldig vandaag

Dit onderwerp bevat de volgende rubrieken.

Article 1 General


1.1 The provisions of this Notice and its Annexes are not applicable to:
a. offshore support vessels, being vessels which:
  1. are mainly engaged in the carriage of stores, materials and pieces of equipment to and from offshore installations; and
  2. are designed with fore accommodation spaces and navigation bridge and with an exposed cargo deck on the aft ship for cargo handling at sea;
b. pontoons, which:
  1. are carried unmanned and towed;
  2. carry only deck cargo;
  3. have a block coefficient of 0.9 or more;
  4. have a breadth/depth ratio, B/D, of more than 3.0; and
  5. have no deck hatches other than hatches with an opening of not more than 1.5 m2 being capable of weathertight closure by means of gaskets and clasps, or small manholes capable of watertight closure.

1.2 Unless indicated otherwise, in this Notice the length, the breadth, the depth and the block coefficient of the ship mean what has been described in Article 2 of Annex I to the Ships Decree 1965 to that end.

Article 2 Inclining test report


A calculation report of the inclining test of the ship should be submitted with the Head of the Shipping Inspectorate for every ship.
This report should contain:
  1. the calculation of the mass of the lightweight ship;
  2. the calculation of the position of the vertical centre of gravity of the lightweight ship above baseline (), according to standard NEN 3085;
  3. the calculation of the position of the longitudinal centre of gravity of the lightweight ship relative to the aft load line or relative to 1/2 Lord (Gl), all this according to the standard NEN 3085.

Article 3 Stability information


3.1 For ships, not being passenger ships, tugs or dredgers, with a length of 24 m or more, the following stability information should be submitted with the Head of the Shipping Inspectorate:
.1 a capacity plan containing the necessary data concerning the holds and tanks. The right position and function of the various compartments should be indicated on the plan by means of a drawing of the longitudinal cross-section of the ship, as well as the necessary horizontal cross-sections over double bottom tanks, deeptanks, etc.
The capacity plan should be accompanied by two tables:
.1.1 a table, stating the different hold volumes (bales and grain), or the cargo tank volumes, with the position of the corresponding vertical centres of gravity above baseline and the longitudinal ones relative to the aft load line or relative to 1/2 Lord, all this according to the standard NEN 3085;
.1.2 a table stating the contents of the tanks, others than as referred to under .1.1, with the position of the corresponding vertical and longitudinal centres of gravity, as indicated in .1.1. In this table the effect of free surfaces of liquids in tanks should also be indicated for each tank;
.2 hydrostatic curves including the curves of ordinate areas (Bonjean curve) and the curves of the ordinate moments1. When the hydrostatic data stated in the inclining test report are determined with the aid of recognized software, the Head of the Shipping Inspectorate may determine that the hydrostatic curves need not be submitted.
For further details with regard to the calculation of the data for the hydrostatic curves, reference is made to Annex III to this Notice, under 1 and 2;
.3 a diagram of the so-called cross curves of static stability for angles of heel of 2, 5, 10, 15, 20, 30, 40, 50 and 60 degrees, being the graphics of KN sinF, as a function of the displacement in tons of 1000 kg(t), including shell and appendages in water with a density of 1.025 t/m3 2.
Here KN sinF is the distance between keelpoint (K) - the intersection of the centreline of the ship with the moulded cross-section at midship - to the line of the buoyancy force, for that particular heeling. For more detailed data concerning the calculation of the cross curves, reference is made to Annex III to this Notice, under 1 and 3.
For ships designed for the carriage of bulk grain, the cross curve of static stability for an angle of heel of 12 degrees should also be calculated, as indicated in Annex XIX to the Ships Decree 1965;
.4 the calculation of the position of the vertical and longitudinal centre of gravity, of fore and aft draughts, of the initial metacentric height (GM) and of the righting lever curves for the following loading conditions of the ship:
.4.1. ship in ballast in the departure condition, without cargo but with full stores and fuel;
.4.2. ship in ballast in the arrival condition, as indicated in 4.1, and with 10 per cent stores and fuel remaining;
.4.3. ship in the departure condition, at summer draft, homogeneously loaded and with full stores and fuel;
.4.4. ship in the arrival condition, loaded as indicated in .4.3, and with 10 per cent stores and fuel remaining;
.4.5. other loading conditions, if regularly occurring, such as, for example:
non-homogeneously loaded ship; depending on the design of the ship eventually instead of the loading conditions mentioned under .4.3 and .4.4, empty deeptanks, if the ship has been provided with deeptanks, stores for a short voyage, container deck cargoes or other deck cargo, not being timber deck cargoes.
When the ship is designed for the carriage of timber deck cargoes, moreover, the required calculations for the following loading conditions of the ship:
.4.6. ship in the fully loaded departure condition with cargo homogeneously distributed in the holds and a timber cargo on deck or on the hatches and with full stores and fuel, where the ship, having regard to the provisions of 4.7 as regards the increase of weight of the cargo, is loaded to the largest possible draught;
.4.7. ship in the fully loaded arrival condition, as indicated in 4.6, and with 10 per cent stores and fuel remaining. In this condition it should be assumed that the weight of the deck cargo has increased by 10 per cent due to water absorption3. When ice accretion on the deck cargo can be expected, this increase in weight has also to be taken into account.
When an amount of water ballast is necessary in any loading condition in order to meet the stability criteria, mentioned under .4, this should be clearly indicated in the calculation of the loading condition involved.
The free surface effect of liquids in tanks should be taken into account during the calculation of loading conditions, mentioned under .4.1 up to.4.7, as well as the effect of the wind on the ship, as indicated in Annex III to this Notice, under 4, respectively under 5.
In every loading condition, the distribution of the cargo and the filling of the tanks should be indicated on a small scale in one or more longitudinal cross-sections of the ship.
.5 a table from which for a sufficient number of draughts (relative to the bottom of the keelplate) the following hydrostatic data of the ship can be read: displacement in fresh water with a density of 1.000 t/m3 including shell and appendages, in tons of 1000 kg;
displacement in water with a density of 1.025 t/m3 including shell and appendages, in tons of 1000 kg;
weight, required for 1 cm change in draught in water with a density of 1.025 t/m3, in tons of 1000 kg;
moment, required for 1 cm total change in trim on the draught scales in water with a density of 1.025 t/m3, in ton-metres;
longitudinal centre of buoyancy relative to the line, as referred to in 2 under .3 in metres;
longitudinal centre of floatation relative to the line as referred to in 2 under .3 in metres;
transverse metacentre above baseline in metres;
In order to be able to determine the various hydrostatic data correctly, the differences in draught have to be assumed sufficiently small. The format of the table is indicated in Annex I to this Notice;
.6 a drawing from which the relation between the draughts read on the draught marks can be easily read, and the mean draught on 1/2 Lord can be deduced. This drawing can be combined with the drawing 'placing draught marks';
.7 a curve of maximum allowable KG' where the criteria, mentioned under 4.1, are just complied with, as a function of the draught in metres relative to the bottom of the keel plate and of the displacement in tons of 1000 kg including shell and appendages in water with a density of 1.025 t/m3, as indicated in Annex II to this Notice. Here the KG' indicates the position of the centre of gravity above the baseline, after this has been corrected for the effect of free surfaces of liquids in the tanks. In the following cases several curves of maximum allowable KG' should be submitted:
.1 if the provisions of Annex III to this Notice, under 1.2., are applicable concerning the effect of the trim on the righting lever;
.2 if in case of the carriage of timber deck cargoes the provisions of Annex III to this Notice, under 3.3.1., are applicable concerning the buoyancy of the timber deck cargo;
.3 in case of the carriage of deck cargoes concerning the effect of the height of the deck cargo on the influence of the wind pursuant to the provisions in Annex III to this Notice, under 5.
The curves of maximum allowable KG' need not be submitted for ships with a limited number of loading possibilities included in all loading conditions, as referred to in .4, under .4.1. up to .4.5.
3.2 For ships, being no tugs or dredgers, with a length of less than 24 m, the following stability information should be submitted with the Head of the Shipping Inspectorate:
.1 the data, mentioned in 3.1, under .1, .2, .3 and .5;
.2 the calculation of the position of the vertical and longitudinal centres of gravity, of the fore and aft draughts, of the initial metacentric height and of the corresponding curve of the righting lever for some characteristic loading conditions of the ship, among which a condition in which the ship has been loaded to the summer load line;
.3 the calculation of the position of the vertical and longitudinal centres of gravity, of the fore and aft draughts, of the initial metacentric height and of the corresponding curve of the righting lever for ships with a non-watertight deckhouse or a wheelhouse, if:
a. the non-watertight deckhouse has a length of more than 15% of the length of the ship and the floor of this deckhouse is situated at less than 900 mm above the freeboard deck. It should be assumed here that there is water in the deckhouse till the level of the sill of the outside door;
b. the floor of the non-watertight deckhouse or the wheelhouse is under the freeboard deck. Here it should be assumed that there is water in the wheelhouse, till the level of the sill of the outside door if this level is higher.
.4 the calculation of the position of the vertical and longitudinal centres of gravity, of the fore and aft draughts, of the initial metacentric height and of the corresponding curve of the righting lever, where all passengers are on board.

3.3 For tugs and dredgers, stability information should be submitted with the Head of the Shipping Inspectorate according to the provisions in 3.2, under .1 and .2.

3.4 For passenger ships with a length of 24 m or more the following stability information should be submitted with the Head of the Shipping Inspectorate:
.1 the data, mentioned in 3.1, under .1, .3, .5, .6 and .7;
.2 the calculation of the position of the vertical and longitudinal centres of gravity, of the fore and aft draughts, of the initial metacentric height and of the corresponding curve of the righting lever for some characteristic loading conditions of the ship, among which conditions in which the ship has been loaded till the maximally allowable draught.


1 These data may be submitted in de form of appropriate tables, or in another presentation, when the same information can be obtained therewith.
2 These data may also be submitted in the form of appropriate tables.
3 It should be noted that there are certain timber deck cargoes of which is known that the increase in weight due to absorption of water can be considerably larger.

Article 4 Stability criteria


4.1 Except for in cases as referred to in 4.5., ships with a length of less than 100 m should in all occurring loading conditions comply with the following criteria:
.1 at an angle of heel of 30 degrees the area under the righting lever should not be less than 0.055 metre-radians and at an angle of heel of 40 degrees or at the angle of flooding (Ff)* if this angle is less than 40 degrees, not less than 0.09 metre-radians;
.2 the increase of the area under the righting lever between an angle of heel of 30 degrees and an angle of heel of 40 degrees or the angle of heel (Ff) if this is less than 40 degrees, should not be less than 0.03 metre-radians;
.3 the righting lever should be at least 0.20 m at an angle of heel of equal to or greater than 30 degrees;
.4 the maximum righting arm should occur at an angle of heel preferably exceeding 30 degrees but not less than 25 degrees;
.5 the initial metacentric height should not be less than 0.15 m.

4.2 Except for in cases as referred to in 4.5., for ships with a length of 100 m and over, the criteria mentioned in 4.1 are considered as directions on the stability in all loading conditions.

4.3 If a ship, irrespective of its length, carries a timber deck cargo which complies with the conditions to be mentioned hereafter, contrary to the provisions in 4.1 the following criteria may be complied with:

4.3.1. the area under the righting lever curve should not be less than 0.08 metre-radians at an angle of heel of 40 degrees or at the angle of flooding (Ff) if this is less than 40 degrees;

4.3.2. the maximum righting arm should not be less than 0.25 m;

4.3.3. the initial metacentric height, after correction for the effect of free surfaces of liquids in tanks and taking into account the increase of the weight of the deck cargo due to absorption of water or accretion of ice, should not be less than 0.10 m.
For the purpose of these criteria, the deck cargo should meet the following conditions:
.1 the wells between the part of the superstructure should be filled with timber over its full length; when there is no limiting superstructure at the after end, the deck cargo should extend at least to the after end of the aftermost hatchway;
.2 athwartships the deck cargo should be as close as possible to the ship's sides; however, it is allowable that the outside of the deck cargo is placed as much as necessary to the inside when the transition of shell plating to deck plating is constructed as a rounded gunwale, provided any area of broken stowage thus created at the side of the ship does not exceed a mean of 4% of the breadth;
.3 the deck cargo should be secured so as to prevent shifting of the deck cargo at great angles of heel of the ship.

4.4 Except for in cases as referred to in 4.5, the following criterium should be complied with in connection with the effect of the wind on a ship, irrespective its length:
the angle of heel occurring due to the wind moment (Fc) should not be more than 50 degrees or the angle of heel where the ship is flooded (Ff) if this is smaller than 50 degrees, or the angle of second intercept between wind heeling lever and GZ curve if this is smaller than (Ff) and 50 degrees.
For further details on the effect of the wind on the stability, particularly the calculation of the wind moment and the occurring angles of heel, reference is made to Annex III, under 5., to this Notice.

4.5 When the shape or design of a ship, or the operational details give causes for it, the Head of the Shipping Inspectorate may determine other criteria than those mentioned in 4.1, under .1, .2 and .4 when these in his opinion provide an equivalent safety.
An equivalent safety is supposed to be achieved in 3.2.3 and 3.2.4, when the list is not greater than 7° and the initial metacentric height, corrected for the effect of free surfaces of liquids, is at least 0.10 m.


*The angle of heel where the ship is flooded (Ff) is the angle of heel where openings in the hull, superstructures or deckhouses, not capable of watertight closure, immerse. For the purpose of this criterium, small openings through which in the opinion of the Head of the Shipping Inspectorate progressive flooding cannot take place, need not be considered as open.

Article 5 Stability information for use on board


5.1 A book, containing the documents mentioned in 3.1, under .1, .3, .4, .5, .6 and .7, should be on board of ships, being no passenger ships, tugs or dredgers, with a length of 24 m and over, the keel of which has been laid on or after 1 April 1977;

5.2 A book, containing the documents mentioned in 3.1, under .1, and 3.2, under .2, should be on board of the following ships:
.1 ships, not being tugs or dredgers, with a length of less than 24 m and the keel of which has been laid on or after 1 April 1987;
.2 tugs and dredgers, the keel of which has been laid on or after 1 April 1977.

5.3 A book, containing the documents mentioned in 3.1, under .1, .3, .5, .6 and .7, and 3.4, under .2, should be on board of passenger ships with a length of 24 m and over and the keel of which has been laid on or after 1 April 1987.

5.4 On board of ships, the keel of which has been laid before 1 April 1977, should be a file containing the documents which were required pursuant to the provisions which were effective when the ship was put into operation and which were approved by the Head of the Shipping Inspectorate.

Article 6


Technical standards or technical requirements laid down in this Notice are equated with equivalent technical standard or technical requirements, laid down by another member state of the European Union or by a state which is party to the Agreement on the European Economic Area.
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