# Tide tables

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Hi there,

I realise that this section of the forum may not be the best for this post, but after going up and down the list, I thought I'd start here. Moderators, please feel free to move it if you see fit.

I have for some time looking to be able calculate tide tables for any given location for a long time now. There is very little I can find in terms of actually calculating them with the necessary parameters - most of them are pre-calculated and ready for download.

Quite by accident, I came across the page below and wondered if anybody by chance was interested in these types of calculations and might have something - at least for FM.

Cheers,

Greg

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Judging from a quick Google search, tide calculations can range from moderately complicated to you-can-get-a-masters-degree-in-it complicated. How accurate do you need it to be, and how much detail do you need? Do you just want high and low times, or do you want to calculate height for a given time? I suppose you could do a simple calculation taking into account only the angles of the sun and moon relative to a position in a 2D model of the solar system. You could get a little more complicated by taking into account the declination of the sun (season) and moon, i.e. 3D model of the solar system. I understand that local currents and topography can also have a big effect, but then you're getting into needing to feed-in lots more location-specific data to the calculation.

Mathematically, we're talking about a harmonic series for the more basic versions, i.e., a sum of sin functions representing the different periodic cycles and with different coefficients representing the relative strengths of their effects. You could pick out which effects you want to take into account (sun and moon phase at minimum, seasons and ellipsoidal orbit effects if you want to get fancier, latitude of the location if you want to show off), and fit a harmonic series with those components to a data set of actual tides.

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Hi jbante,

Thank you for your reply. I sort of knew that I was opening a can of worms with that question as it is a complex issue.  All the various formulae I have seen still refer to other variables which are PROVIDED and not calculated which makes it difficult to make a stand-alone solution.

I suppose even being able to look at the high tides and low tides of any day (past or present) would be pretty good - if it were possible to do it that way.

Cheers,
Greg

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For even the simplest of the calculation options, some historical data is necessary to fit the harmonic series. However, as long as you don't need the accuracy provided by local current and topography details, you shouldn't need that reference data after you've fit your coefficients.

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Hi,

I think Ive bitten off more than I can chew with this project. Thank you for your response.

Cheers,
Greg

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