The Government of India Deep Sea Fishing Station at Bombay and the Offshore Fishing Stations at Veraval, Mangalore, Cochin, Visakhapatnam and Tuticorin have been employing in the exploratory fishing operations different types of power vessels which vary greatly in their gross tonnage, net tonnage, brake horse power, length of body, draught etc. even though most of them use more or less the same or similar types of otter trawls. It is well known that, suitably geared a larger boat would generally bring about a greater fishing mortality than a smaller one in a unit amount of time when fishing in the same ground. The capacity of a vessel to catch more or to catch less as compared with another vessel is independent of the density of the population and is related in some way to the makeup of the vessel itself. In computing catch statistics of different vessels, 'standardisation of fishing time according to their fishing powers' (Beverton and Holt 1957, P. 172) being essential, the present work has been attempted based on available data from the exploratory fishing operations of the vessels viz-, 'Jheenga', 'Bumili' and 'Meera' from Bombay.