Time and Tide Clocks

[GordMay]

Originally Posted by GordMay

This map shows the geographic distribution of different tidal cycles. ..

A better tide map from:
8(r) Ocean Tides

[Bash]

Originally Posted by DJBrookster

Sorry but there seems to be an under current of reliance on electrical equipment. Plotters and apps are great but can always let you down.

Let's see, on my boat there are two chart plotters backed up by two handheld gps systems backed up by two VHF radios (in our areas the tides are broadcast on NOAA weather radio channels), backed up by an iPhone and a Blackberry, both equipped with tide apps. I've got eight electronic instruments on which I can retrieve tidal data without having to resort to an archaic table incapable of adjusting tides for exact locations in exact times.

Hmmm.

The tidal data on the paper tide charts is only good for the current year and doesn't extend more than 100 miles from here. The tidal data on my iPhone extends well beyond my expected lifetime and covers every tidal station on the west coast from Canada through Mexico, and every one of the 50 states that comprise the United States of America. American Samoa is in there too, I've just noticed.

That little paper chart is sitting in the chart table in my nav station, which is inaccessible to me at the moment since I'm in my office. However, I can use the iPhone right now to tell me the exact tidal stage the moment I'm planning to leave the dock this weekend, down to the inch.

When they stop giving out those paper chart books free at chandleries, I won't miss them for a minute. I certainly wouldn't waste hard-earned money on one.

[roger.waite]

An example from my area showing why tables, charts, and height and flow predictions (paper-based or gizmo-based) should be used with an eye on weather conditions, and what is actually happening ...

"The tidal flow through Cook Strait is unusual. On each side of the strait the tide is almost exactly out of phase, so high water on one side meets low water on the other. Strong currents result, with almost zero tidal height change in the centre of the strait. Although the tidal surge should flow in one direction for six hours and then the reverse direction for six hours, a particular surge might last eight or ten hours with the reverse surge enfeebled. In especially boisterous weather conditions the reverse surge can be negated, and the flow can remain in the same direction through three surge periods and longer. This is indicated on marine charts for the region.[10]
"There are numerous computer model representations of the tidal flow through Cook Strait. While the tidal components are readily realizable,[11] the residual flow is more difficult to model.[12]


FWIW