Abstract: Apparatus for presenting tidetable data in a form visually readable to the average person in terms of the year, month, day and hour of occurrence, exacting information regarding current flow, i.e. the direction of current flow, the relative strength of current flow, and the period of current flow, at a given location. A preferred apparatus is comprised of a stator, and slide. The stator is suitably an elongate member along a horizontal side of which days of the week are scribed and scaled off in consecutive order, preferably with each daily period being further sub-divided into a morning period and evening period. The morning and evening periods are in turn sub-divided into hourly periods. A vertical scale provided on the stator ranges from a base line of zero upwardly, or in a positive direction, to a high point representative of the tidal range, and downwardly below the base line of 0, or in a negative direction, to a low point representative of the tidal range.