Section 10 Omission of hatch covers

10.1.1 Where it is intended to omit hatch covers for one or more cargo holds, the requirements of this Section are to be complied with and the notation Hatch Covers may be omitted in Hold (No(s) ...) will be assigned. Attention is drawn to the Guidance Notes for the Omission of Hatch Covers on General Cargo Ships and MSC/Circular.608/Rev.1 – Interim Guidelines for Open-top Containerships – (Adopted on 5 July 1994).

10.1.2 The requirements of this Section are applicable to container ships where one or more cargo holds are not fitted with hatch covers and general cargo ships where the hatch covers can be completely or partially removed.

10.1.3 The transport of solid bulk cargoes is not normally permitted without weathertight steel hatch covers.

10.1.4 Proposals for the omission of hatch covers are required to be agreed by the National Authority in order that an exemption from the Load Line Convention requirements for hatch covers can be obtained.

10.2.1 Proposals for the omission of hatch covers are to include details, established by model tests or alternative means, of the quantity of water likely to ingress the cargo holds under the worst sea-going and weather conditions, and the means by which it is to be efficiently and safely discharged. The guidelines given in MSC/Circular.608/Rev.1 – Interim Guidelines for Open-top Containerships – (Adopted on 5 July 1994) are an acceptable approach for container ships. For general cargo ships, attention is drawn to Ch 1, 1.5 Intact stability of the Guidance Notes for the Omission of Hatch Covers on General Cargo Ships. The approach taken to determine the water ingress is to be agreed with the Flag Administration.

10.2.2 For general cargo ships, the permeability of the cargo holds is to be taken as 0,9 (holds are assumed to be empty).

10.2.3 For container ships, the permeability of the holds is to be taken as 0,7 (fully loaded container holds).

10.2.4 The maximum head of water in the open holds need not be taken greater than 2 metres when considering strength aspects.

10.3.1 For container ships, the requirements of Pt 4, Ch 8, 16.11 Hull girder ultimate strength are to be complied with where the still water vertical hull girder bending moment is to be calculated for the intact flooded condition, see Pt 3, Ch 9, 10.2 Loading due to water ingress 10.2.1, Pt 3, Ch 9, 10.2 Loading due to water ingress 10.2.3 and Pt 3, Ch 9, 10.2 Loading due to water ingress 10.2.4.

10.3.2 For general cargo ships, the requirements of Pt 3, Ch 4, 5 Hull bending strength and Pt 3, Ch 4, 6 Hull shear strength are to be complied with where the still water vertical hull girder bending moments and shear forces are to be calculated for the intact flooded condition, see Pt 3, Ch 9, 10.2 Loading due to water ingress 10.2.1, Pt 3, Ch 9, 10.2 Loading due to water ingress 10.2.2 and Pt 3, Ch 9, 10.2 Loading due to water ingress 10.2.4.

10.3.3 As an alternative to the requirements of Pt 3, Ch 9, 10.3 Longitudinal strength 10.3.2, increased strength limits can be assigned based on a service factor of 0,8 provided that a wave height limitation is placed on the ship for loading conditions where it is proposed to omit hatch covers. This wave height limitation is to correspond to the significant wave height assumed when determining the degree of water ingress and is not to be taken as greater than 8,5 metres. The descriptive note OHCF() is to be assigned where the wave height limitation is to be appended to the descriptive note within brackets. The strength limits are to be named ‘hatch coverless strength limits’.

10.4.1 Transverse watertight bulkheads are to be assessed as deep tank bulkheads (including welding) up to a height corresponding to the expected water ingress plus 0,5 metres, i.e. if there is water ingress up to a height of 1,5 metres then the height to which the bulkhead is assessed as a deep tank bulkhead is 2 metres, see also Pt 3, Ch 9, 10.2 Loading due to water ingress.

10.4.2 Longitudinal watertight bulkheads are to be assessed as deep tank bulkheads (including welding) up to a height corresponding to the expected water ingress plus 0,5 metres, i.e. if there is water ingress up to a height of 1,5 metres then the height to which the bulkhead is assessed as a deep tank bulkhead is 2 metres.

10.4.3 For general cargo ships, the requirements of Pt 3, Ch 3, 5.4 Design pressure for partially filled tanks for partially filled tanks are to be complied with.

10.4.4 The loading on the inner bottom resulting from the combination of water and cargo loading is not to exceed the design loading. Special attention is to be paid to the point loading of unusual cargoes being carried by general cargo ships.

10.4.5 For container ships, where it is proposed to fit hatch covers on top of container stacks to act as wave breakers, the strength of the securing arrangements and hatch coaming is to be specially considered.

10.5.1 For general cargo ships, a section is to be included in the Loading Manual describing the circumstances under which hatch covers can be omitted. The information provided is to include any wave height limitations as well as the permitted design loading for the inner bottom for each cargo hold and the assumed water ingress. Guidance is also to be provided on how to determine whether the proposed loading of the inner bottom exceeds the design loading.

10.5.2 If the requirements of Pt 3, Ch 9, 10.3 Longitudinal strength 10.3.3 are applicable then the hatch coverless strength limits are to be included in the loading manual in addition to the seagoing strength limits.

10.5.3 For general cargo ships, a loading instrument is to be installed on board the ship irrespective of the length of the ship, see Pt 3, Ch 4, 8.3 Loading instrument.

10.6.1 If freeing ports are provided, they are to be fitted on both sides of each open cargo hold, subject to the following:

• the number, size and location of the freeing ports on each side of each open hold are to be sufficient to prevent the accumulation of water above the level defined in Pt 3, Ch 9, 10.2 Loading due to water ingress; and
• efficient means of closure to prevent the accidental ingress of water is to be provided. Such means shall be operated from above the freeboard deck. In the case of a ship operating in areas where icing is likely to occur, these arrangements are to be suitable to enable the freeing ports to operate efficiently under such conditions.