Regulation 16 - Hatchways closed by weathertight covers of steel or other equivalent materials

(1) All hatchways in position 1 and 2 shall be fitted with hatch covers of steel or other equivalent material. Except as provided in regulation 14 (2), such covers shall be weathertight and fitted with gaskets and clamping devices. The means for securing and maintaining weathertightness shall be to the satisfaction of the Administration. The arrangements shall ensure that the tightness can be maintained in any sea conditions, and for this purpose tests for tightness shall be required at the initial survey, and may be required at renewal and annual surveys or at more frequent intervals.

Hatch cover minimum design loads

(2) For ship's of 100 m in length and above:

(a) Position 1 hatch covers located in the forward quarter of the ship's length shall be designed for wave loads at the forward perpendicular, calculated from the following equation:

where:

L_H	=	is L for ships of not more than 340 m but not less than 100 m in length and equal to 340 m for ships of more than 340 m in length;
L	=	is the length of the ship (meters), as defined in regulation 3;
a	=	is given in table 16.1,

and reduced linearly to 3.5 t/m² at the end of the forward quarter's length, as shown in table 16.2. The design load used for each hatch cover panel shall be that determined at its midpoint location.

(b) All other position 1 hatch covers shall be designed to 3.5 t/m².
(c) Position 2 hatch covers shall be designed to 2.6 t/m².
(d) Where a position 1 hatchway is located at least one superstructure standard height higher than the freeboard deck, it may be designed to 3.5 t/m².

	a
Type B freeboard ships	0.0074
Ships assigned reduced freeboard by regulation 27(9) or (10)	0.0363
Table 16.1

(3) For ships 24 m in length:

(a) Position 1 hatch covers located in the forward quarter of the ship's length shall be designed for wave loads of 2.43 t/m² at the forward perpendicular and reduced linearly to 2 t/m² at the end of the forward quarter's length as shown in table 16.2. The design load used for each hatch cover panel shall be that determined at its midpoint location.
(b) All other position 1 hatch covers shall be designed to 2 t/m².
(c) Position 2 hatch covers shall be designed to 1.5 t/m².
(d) Where a position 1 hatchway is located at least one superstructure standard height higher than the freeboard deck, it may be designed to 2 t/m².

(4) For ships between 24 m and 100 m in length, and for positions between FP and 0.25L, wave loads shall be obtained by linear interpolation of the values shown in table 16.2.

	Longitudinal position
	FP	0.25L	Aft of 0.25L
L>100 m
Freeboard deck	Equation in 16(2)(a)	3.5 t/m²	3.5 t/m²
Superstructure deck	3.5 t/m²		2.6 t/m²
L=100 m
Freeboard deck	5 t/m²	3.5 t/m²	3.5 t/m²
Superstructure deck	3.5 t/m²		2.6 t/m²
L=24 m
Freeboard deck	2.43 t/m²	2 t/m²	2 t/m²
Superstructure deck	2 t/m²		1.5 t/m²
Table 16.2

(5) All hatch covers shall be designed such that:

(a) the product of the maximum stress determined in accordance with the above loads and the factor of 1.25 does not exceed the minimum upper yield point strength of the material in tension and the critical buckling strength in compression;
(b) the deflection is limited to not more than 0.0056 times the span;
(c) steel plating forming the tops of covers is not less in thickness than 1% of the spacing of stiffeners or 6 mm if that be greater; and
(d) an appropriate corrosion margin is incorporated.

Securing arrangements

(6) The means for securing and maintaining weathertightness by other means than gaskets and clamping shall be to the satisfaction of the Administration.

(7) Hatch covers which rest on coamings shall be located in their closed position by means capable of withstanding horizontally acting loads in any sea conditions.