It shall be sufficient compliance with regulation 4 for there to be kept, in place of any instrument or appliance thereby required to be kept on board the ship, an instrument or appliance designed to fulfil the same function, for so long as it remains in good serviceable condition, if it was kept on board the vessel on the date on which these Regulations come into operation.

In the case of a ship which, on the date on which these Regulations come into force, is on a voyage, there may be kept on board the ship, in place of the medical stores required by regulation 4 to be kept on board it, the medical stores as it would be required to have on board if the Regulations referred to in regulation 1(2) had not been revoked; but this paragraph shall cease to apply to a ship at the time it arrives at a port in the United Kingdom or at the expiration of six months from the date on which these Regulations come into force, whichever shall be the earlier.