Section 2(c) in The Merchant Shipping (Tonnage Measurement of Sailing Vessels) Rules, 1960
(c)"depth" means(i)in the case of decked vessels, the vertical distance at the centre line from the top of the floor timber at centre to the inside of the tonnage deck at side;(ii)in the case of open vessels, the vertical distance measured from the top of the floor timber to the upper strake of hull planking;
