Where any gunpowder, rockets, or other explosive are on board any ship in pursuance of the provisions of the F1M1Merchant Shipping Act 1894. and the Acts amending the same, or any order or regulation made under any of those Acts, nothing in this Act shall apply to such gunpowder, rockets, or explosive, except that the conveyance and keeping thereof on board the ship or elsewhere while the ship is in harbour shall be subject to the byelaws under this Act, and byelaws under this Act may be made for regulating such conveyance and keeping.