Rule of 12ths

[Wolfy]

Hi people

Anyone know how to calculate the rule of 12s easily ? i often get muddled with this and need to revise it :(

thanks

Wolfy

[Steve Plotkin]

Hi people

Anyone know how to calculate the rule of 12s easily ? i often get muddled with this and need to revise it :(


The best way I find to remember this is 1,2,3 3,2,1

The tide moves 1 1/12 in the first hour, 2 in the 2nd, 3 in the third etc.

If the tide range is 2.4 meters between H and L water, then the tide moves 0.2m per hour i.e.

1 hour 0.2m Total 0.2m 1
2 hours 0.4m 0.6m 2
3 hours 0.6m 1.2m 3
4 hours 0.6m 1.8m 3
5 hours 0.4m 2.2m 2
6 hours 0.2m 2.4m 1

Add this to your start number (if your on a rising tide)

Hope that this helps

Steve