City Sailingvideo

Tidal Streams, help with tidal flow, diamonds and atlases

2 July 2020 · 18 min · 20K views

What this video covers

Calculating tidal stream direction and speed requires referencing a standard port, such as Victoria or Dover, to determine the correct chart or tidal diamond data.2:19 Tidal Stream Atlases provide 13 charts representing the flow for each hour before and after high water at the reference port.0:48 Each chart remains valid for a 60-minute window, spanning 30 minutes before to 30 minutes after the specific hour mark.9:32 When using these atlases, identify the reference port listed at the top of the page, as using the wrong port results in inaccurate navigation data.2:00

Tidal diamonds provide point-specific data, including direction and speed, which are also referenced to a standard port.6:07 To determine if a tide is spring or neap, calculate the tidal range by subtracting the low water height from the high water height and comparing the result to the mean ranges provided in the training almanac.15:11 When calculating, always account for daylight saving time by adding one hour to tide table data for non-shaded areas.14:53 Mapping out the hourly intervals on a blank sheet of paper helps prevent errors when interpolating between tide times.11:16

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