| 摘要 |
A tidal calculating wheel for determining times and/or heights of high and/or low water at secondary ports with reference to a standard port, comprising at least two disks placed on top of each other, secured together through their centres (0) by a central fastener (4) which allows the disks to rotate. Each face of the inner disk (1) is divided into divisions (S), which contain secondary port differences. The time or height at a secondary port being determined by relatively rotating the disks (1, 2, 3) until the desired secondary port tidal difference is visible through the appropriate window (A, B, C, D or E).
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