(1)A ship shall not in any year be required to make payments on account of light dues—
(a)if the ship is a home-trade ship, for more than ten voyages; and
(b)if the ship is a foreign-going ship, for more than six voyages; and
(c)if the ship makes voyages during the year both as a home-trade and as a foreign-going ship, for more than ten voyages, counting each voyage made as a foreign-going ship as a voyage and a half.
Provided that no steamer shall be required to pay more than one shilling and fourpence halfpenny per ton, and that no sailing vessel shall be required to pay more than one shilling and a penny halfpenny per ton in any year.