Section 17(3)(b) in The Merchant Shipping (Crew Accommodation) Rules, 1960
(b)within 5.10 centimetres of a bulkhead of the ship's side unless the bed is so supported and the room so constructed as to avoid harbouring dirt and vermin in or near the bed, to enable the bedding to be kept clean and dry and to minimise the soiling of paintwork in way of the bed; or