The number of persons which a lifeboat shall be permitted to accommodate shall be equal to the greatest whole number obtained by dividing the capacity in cubic metres by—

in the case of a lifeboat of 7,3 metres (24 feet) in length or over 0,283 (or where the capacity is measured in cubic feet 10);

in the case of lifeboats of 4,9 metres (16 feet) in length 0,396 (or where the capacity is measured in cubic feet 14); and

in the case of lifeboats of 4,9 metres (16 feet) in length or over but under 7,3 metres (24 feet) a number between 0,396 and 0,283 (or where the capacity is measured in cubic feet between 14 and 10), to be obtained by interpolation;

Provided that the number shall in no case exceed the number of adult persons wearing life-jackets which can be seated without in any way interfering with the use of oars or the operation of other propulsion equipment.