157(1)Where the owner of a ship incurs liability under section 153 by reason of a discharge or escape which has occurred without his actual fault or privity then—
(a)he may limit that liability in accordance with the provisions of this Chapter, and
(b)if he does so, his liability (that is to say, the aggregate of his liabilities under section 153 resulting from the discharge or escape) shall not exceed 133 special drawing rights for each ton of the ship’s tonnage nor (where that tonnage would result in a greater amount) 14 million special drawing rights.
(2)For the purposes of this section the tonnage of a ship shall be ascertained as follows—
(a)where the registered tonnage of the ship has been or can be ascertained in accordance with the tonnage regulations, the ship’s tonnage shall be the registered tonnage of the ship as so ascertained but without making any deduction required by those regulations of any tonnage allowance for propelling machinery space;
(b)where the ship is of a description with respect to which no provision is for the time being made by the tonnage regulations, the tonnage of the ship shall be taken to be 40 per cent of the weight (expressed in tons of 2,240 lbs) of oil which the ship is capable of carrying;
(c)where the tonnage of the ship cannot be ascertained in accordance with either paragraph (a) or paragraph (b) above, a surveyor of ships shall, if so directed by the court, certify what, on the evidence specified in the direction, would in his opinion be the tonnage of the ship as ascertained in accordance with paragraph (a), or (as the case may be) paragraph (b), above if the ship could be duly measured for the purpose; and the tonnage stated in his certificate shall be taken to be the tonnage of the ship.