21In section 30 of the Merchant Shipping Act 1970 (which provides among other things that a seaman employed in a ship registered in the United Kingdom who persistently neglects his duty or disobeys orders or combines with other seamen to do so or to impede the ship's progress shall be liable on summary conviction to a fine not exceeding £100) for the words from " summary conviction " to " £100 " there shall be substituted the words " conviction on indictment, to imprisonment for a term not exceeding two years and a fine and, on summary conviction, to a fine not exceeding £1,000 ".