Section 17(7)(b) in The Merchant Shipping (Crew Accommodation) Rules, 1960
(b)The minimum size of beds provided in a ship of 3000 tons or over for the Chief Navigating Officer and Chief and Second Engineers shall be atleast 2000 millimetres by 900 millimetres in a passenger ship and atleast 2000 millimetres by 1100 millimetres in any other ship, the measurement in each case being taken inside the lee boards or lee rails, if any, at right angles to each other.]