Calculating tidal differences for secondary ports

Re: Secondary port info - WARNING

they speak English on a good day in Bembridge then drop into some strange lingo on a bad day!

Ian
 
I nearly messed up on my YM Practical on the Bembridge calculation - nearly got caught out as I started using the data for Bembridge rather than the data for Lifeboat Slip. Just spotted it in time!.

Dave
 
Try this:-

c/d=t/T

so further correction to the tabulated data c =dt/T

d= the difference between the tabulated corrections you are using
t= the difference between the given and tabulated times at the STANDARD PORT
T= the difference between the successive tabulated times at the STANDARD PORT


also c/d=h/H

where h= difference between tabulated heights
H= difference between the successive tabulated heights at the standard port.


You will have to 'inspect' the data given to work out if the correction should be + or - . It 's clear which way to go to stay inside the max and min limits.



Dave.
 
Ok give it a go,

locate HW , LW, and tide hights for standard port.

Go to secondary port details.

On graph paper draw a line, mark high water time above the line, secondary port differance below the line, mark your standard port HW time and read the secondary difference below the line.

Do same graph for low water.

Do same type of graph and mark standard port MHWS and MHWN along top, and secondary height difference below, mark HW along top, read difference below.

Do same for low water

Takes a minute to do, and it's all there to see.

Must work as I've just worked it out again from my YM notes.


Brian
 
[ QUOTE ]
In practice the differences for most of the places I have been are so small that I can do it in my head.

[/ QUOTE ]

Try doing it for Port Ellen (Islay). But make sure you do the time correction first. Try to get within a foot (0.3m).
 
From the discussion it would seem that your tides are regular and so follow the predictions quite accurately. In some places we sometimes get variations of hours with the tide running the "wrong" way due effects of wind, etc - do you not get the same?

{Maybe I canna read the Tables, secondary ports I do by the tea leaves/forums/images/graemlins/smile.gif}

John
 
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