Numbers alongside the arrows on tidal stream charts

[Thepipdoc]

This is probably a silly question but as the saying goes “ask a question and feel like a fool for moment, or don’t ask the question and be a fool forever”!

What do the numbers alongside the tidal stream arrows mean on tidal charts?
i.e. an arrow pointing to the west at a particular time of the day accompanied by two numbers, typically 01,05 or 15,29?

It surely can be the speed of the tide can it?

 

[tillergirl]

First number is neap rate, second is spring rate. So 05,10 would be half a knot on neaps and one knot on springs. 15,29 is 1.5 knots neaps and 2.9 knots springs

 

[theforeman]

the numbers refer to the rate of the tidal stream, the arrow of course to the direction. the higher number is the rate at springs and the lower number at neaps. the numbers have to be read as if there is a decimal point between them - ie 15, 05 = 1.5 knots springs, 0.5 knots neaps.

 

[Thepipdoc]

Brilliant - thanks for this.
Makes sense now, and I already feel less of a fool!

 

[tt65]

..................and to interpolate or even extrapolate between them if it is a time between neap and springs, then use the computation of rates tables that can be found in most almanacs. pvt me if you need a blank one.

 

[chart5011]

We have recently added explanations with diagrams and examples to the website below, coverage includes Tidal Streams Atlases, Tidal Diamonds, Tide Tables and Secondary Port Calculations etc.

 

[Thepipdoc]

Again-- thanks for the excellent responses.

 

[Lady Campanula]

This is probably a silly question but as the saying goes “ask a question and feel like a fool for moment, or don’t ask the question and be a fool forever”!

There are no silly questions; only silly answers - like this one.

And everyone on 'ere who knows has had to ask the same question at some time. Ask 'em another......

 

[ghostlymoron]

Have you considered going on a Dayskipper course. There may be other useful things you don't know about.

 

[colingr]

We have recently added explanations with diagrams and examples to the website below, coverage includes Tidal Streams Atlases, Tidal Diamonds, Tide Tables and Secondary Port Calculations etc.

Website blow what (or where)? Or am I missing something?

 

[Iain C]

I find it amazing that to "save space" the TSA omits the decimal point. I betcha if the original poster had seen 0.7/1.5 he would have worked it out.

And even more amazing that if you look at the tidal stream diagram on a chart rather than an atlas, the neap/spring rates are the opposite way round to the atlas.

Erm, why?

 

[chart5011]

Website blow what (or where)? Or am I missing something?

www.cockpitcards.co.uk

 

[colingr]

www.cockpitcards.co.uk

Aha

Further below!