Procedure to become an open-top general cargo ship
With regard to the International Convention on Load Lines (ICLL) regulation 14, and taking into account ICLL article 8, the NSI permits:
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existing open-top general cargo ships for which the keels are laid, or which are at a similar stage of construction, before the 1st of February 2018; and
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new open-top general cargo ships:
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for which the building contract is placed on or after the 1st of February 2018; or
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in the absence of a building contract, the keels of which are laid or which are at a similar stage of construction on or after the 1st of July 2018; or
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the delivery of which is on or after the 1st of July 2024; or
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ships, converted on or after the 1st of February 2018, with a keel laying date before the 1st of July 2018,
to be exempted from the requirement for cargo and other hatchways to be closed by weathertight covers of steel or other equivalent materials, provided that:
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a new open-top general cargo ship complies with the provisions of the Netherlands equivalent arrangement (GISIS no. XQ42482);
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an existing open-top general ship complies with the provisions of the Netherlands equivalent arrangement (GISIS no. XQ42482), with the following exceptions:
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In case the maximum hourly rate of ingress of green water in any one open hold determined from the model testing (measured in m3/hour and converted in mm/hour) is more than 66 mm/hour, the following shall apply:
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The stability of an existing open-top general cargo ship in intact condition shall be (re)calculated in accordance with section 6 of the Netherlands equivalent arrangement (GISIS no. XQ42482); and
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An addendum to the existing approved stability documents shall be approved by the RO and placed on board.
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In case the maximum hourly rate of ingress of green water in any one open hold determined from the model testing (measured in m3/hour and converted in mm/hour) is 66 mm/hour or less, the stability of an existing open-top general cargo ship in intact condition is not required to be (re)calculated. The existing approved stability documents may suffice;
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appropriate text shall be included reflecting paragraph 2.1 or 2.2 in the International Load Line Exemption Certificate issued to the existing open-top general cargo ship; and
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an International Load Line Exemption Certificate shall be issued with a reference to the Netherlands equivalent arrangement (GISIS No. XQ42482), see further below.
relaties1Further guidance on 'XQ42482 - Section 6.5' (tween deck – drainage)
Distance for the bulwark height
It is the opinion of the NSI that the situation with which a comparison can be made is the case of excess heights of bulwarks (refer to case a below) or a well (refer to case b below). The NSI during the first draft of the guidelines for open top made an attempt to make use of the USCG interpretation for excess height of bulwarks. As no consensus could be reached within the group it was decided to delete that part till there is further experience or an actual request. At that time it was proposed to use the height measured from the freeboard deck to the top of the hatch coaming. The reason is that the ingress of water is, in our opinion, not influenced by the position of the tween-deck panel. The determining factors for the ingress of water (apart from the ship's GM and seakeeping characteristics) are the freeboard deck in relation to the ship's draft and the height of the coaming. Having said that, once water flows into the cargo hold then the location of the top of the coaming in relation to the location of the tween deck panels would function as an obstruction for the water to flow out (case b below). Summarizing, based on the above there may be two functions:
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Case a) the height of the coaming may function as a protection from water to enter the cargo hold. In that case the distance measured should be from the freeboard deck to the top of the coaming. This case resembles the case of excess height of bulwark. For that purpose ICLL, regulation 24(1) in conjunction with the interpretation of the USCG Load Line Technical Manual Ch. 3 can be used.
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Case b) the location of the top of the coaming may function as an obstruction for the water to escape. In that case the distance should be measured from the tween-deck panel to the top of the coaming. This would lead to an unrealistic increase of the area. In that case the situation resembles more a well, where provisions of freeing should be made for the water to escape rapidly to the double bottom. For that purpose ICLL, regulation 24(4) may be used. Where reference is made to 'actual height of bulwark' the height may be considered as twice the height of the maximum accumulated water inside the hold determined during the model test plus the amount of tropical rainfall multiplied by 3 hours. By multiplying the height by two, the heel of the vessel is accounted for (accumulation of water on one side)
Effectiveness of freeing port area
The effectiveness of the calculated freeing port area (e.g. the total area of gaps between the tween decks) should be checked by calculating the time for drainage by direct calculation, for example in accordance with simple a Bernoulli calculation. The calculated time should be equal or less than 60 sec.
The reason why we request an additional calculation is to verify the effectiveness of the freeing ports. This check is also done for Load Line for the freeing port area in the bulwark. The effectiveness can be checked in two ways: either with a time to flow calculation or an area check like this is done for the freeing port area in bulwarks required by ICLL, regulation 24(3).
The reason why we proposed to make use of the time to flow calculation, is because it is not easy to provide an equivalent for the free flow area in accordance to ICLL, regulation 24(3). The time of 60 sec originates from SOLAS when calculating intermediate stages of flooding. When flooding occurring within 60 seconds, it is considered instantaneous (ref. MSC.Res.281(85), Part B, Regulation 7-2.2).
Assessing the freeing area openings between the tween deck hatches
The freeing area shall be calculated on the basis of twice the amount of water entering the cargo hold obtained from the model test, plus the amount of tropical rainfall multiplied by 3 hours.
The effectiveness of the freeing port area shall be verified by calculating the time to flow to be within 60 seconds. The amount of water to be used for that purpose shall be the maximum hourly rate of water ingress measured for the worst heading during the tests.
What if the freeing area is less than required
As there is no simple rule to assess how much water should be accounted for on the tween deck panel, it is essential that ample provisions shall be made for rapidly freeing the water from the tween deck. That means that the tween deck hatches shall be placed in such a way to ensure drainage of water. That follows the same principle as for the freeing port requirement included in the ICLL, regulation 24. After calculating the freeing port area as described above an additional check should be done by calculating the time for drainage. The way how to calculate that is up to the RO and the time for drainage should in no case exceed 60 seconds.
Standardization of Certification Open Top
In order to align all certificates / ships with the same conditions, the ROs shall use the text as described below (when applicable for the ship) for the related certificates. The applicable text shall be aligned at the first renewal / initial survey after the 'Entry-into-force date' of this Instruction.
International Load Line Exemption Certificate
The International Load Line Exemption Certificate shall be issued for ships which are designed to sail in Open-Top condition under the requirements of this Instruction. The following (general) conditions applies:
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'Freeboard based on model test in accordance with MSC/Circ.608/Rev.1';
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'Increased bilge capacity based on model test in accordance with MSC/Circ.608/Rev.1';
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'Stability complies with requirement for "Open" vessel as indicated in the approved stability booklet';
Further, based on the ships model / type / testdata / restrictions, additionally on the above, other conditions may consist, e.g.:
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'In open-top condition the tweendeck panels to be placed in store position or not be on board';
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'The stowed hatch covers are to be positioned at aft end (between frames ….) and fore end (between frames ….) of the hold.'
It has to be clarified for which draught the conditions are acceptable, by using the text:
'The (exemption-) certificate is valid for a summer load line draught of ..,.. m operating in open top mode according to GISIS No. XQ42482.'
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'Under the authority conferred by the provisions of': ILLC 1966 and the protocol of 1988, article 6(2)
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'Exempted from the requirements of': ILLC 1966 and the Protocol of 1988, Annex I reg. 14(1)
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Besides, a clear reference (e.g. to the related certificate number) will be made on the exemption certificate to which ILL certificate the exemption applies, i.e. ILL certificate for open top condition.
Based on the ships model / type, additionally on the items above, other conditions may consist. Such addition shall be mentioned on the ILLC exemption certificate at the discretion of the RO. Besides, such conditions shall be communicated to the NSI in order to align the certification text on the certificates.
Please also note that an exemption should be issued in combination with the Cargo Ship Safety Certificate in case no fixed fire-extinguishing system is functional during sailing in open top.
Cargo Ship Safety Construction Exemption Certificate - Fixed fire-extinguishing system
In case the ship's fixed fire-extinguishing system (i.e. a fixed carbon dioxide or inert gas fire-extinguishing system) will not be effective when the ship undertakes a voyage in the 'open-top' mode, the ship may be exempted from SOLAS regulation II-2/10.7.1.3 or, in case the ship is engaged in the carriage of dangerous goods in any cargo space, regulation II-2/10.7.2. The following condition shall be added on the exemption certificate:
'This exemption certificate is valid when the vessel is operating in Open Top mode according to GISIS No. XQ42482.
Only non-combustible cargoes and non-dangerous goods, such as (but not limited to) steel modules, steel cranes, steel ship hulls, boilers and heaters to be transported in the cargo hold (without the hold water spray system installed).'
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'Under the authority conferred by the provisions of': SOLAS regulation I/4(b);
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'Exemption from the requirements of': SOLAS regulation II-2/10.7.1.3 en 10.7.2;
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The Document of Compliance (DoC) for carriage of dangerous goods
In case the ship is suitable for the carriage of dangerous goods, as referred to in SOLAS regulation II-2/19, but when it is not allowed to transport (any) dangerous goods in open top condition, the following text has to be added:
'The carriage of dangerous goods is only permitted with all hatch covers of the applicable cargo hold in closed position'
When the ship has a removable hold water spray system, the following text has to be added:
'In case no fixed fire extinguishing system is in place only non-dangerous goods and non-combustible cargoes, such as (but not limited to) steel modules, steel cranes, steel ship hulls, boilers and heaters shall be carried in open-top condition. '
In case a ship is allowed to carry several (but not all) categories of dangerous goods in open top condition, this shall be clearly marked on the certificate including extra applicable conditions, if necessary.
The categories of dangerous goods to be transported in open top are limited by the NSI to:
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Class 1.4
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Explosives, substances and articles which present no significant hazard
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Class 2.1
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Flammable gasses
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Class 2.2
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Non-flammable, non-toxic gasses
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Class 2.3
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Toxic gasses (non-flammable)
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Class 3
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Flammable liquids - high flashpoint, ≥23°C but ≤60°C
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Class 4.1
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Flammable solids, self-reactive substances, solid desensitized explosives and polymerizing substances
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Class 4.2
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Substances liable to spontaneous combustion
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Class 5.1
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Oxidizing substances
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Class 6.1
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Toxic substances (liquids) – non flammable
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Class 6.1
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Toxic substances (solids)
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Class 8
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Corrosives (liquids) - high flashpoint, ≥23°C but ≤60°C
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Class 8
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Corrosives (liquids) - non flammable
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Class 8
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Corrosives (solids)
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Class 9
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Miscellaneous dangerous substances and articles
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The Statement of Compliance (SoC) for the carriage of solid bulk cargoes
In case the ship is suitable for the carriage of solid bulk cargoes other than grain, as referred to in SOLAS regulation VI/7, in accordance with the provisions of the International Maritime Solid Bulk Cargoes (IMSBC) Code, the following text shall be included in the Statement of Compliance for Carriage of Cargo in Bulk, if issued by the RO:
'The carriage of solid bulk cargoes is only permitted with all hatch covers of the cargo hold in closed position'
See also the Information to Shipping for more details related to this topic: Transport of solid bulk cargoes
Document of Authorization for the carriage of Grain
In case the ship is suitable for the carriage of grain, as referred to in SOLAS regulation VI/9, in accordance with the provisions of the International Code for the Safe Carriage of Grain in Bulk, the following text shall be included in the Document of Authorization:
'The carriage of Grain is only permitted with all hatch covers of the cargo hold in closed position'