2009 Tidetables

[Severnman]

Those of you who have already got next year's tidetables may notice a fundamental change to Arrowsmiths handy sized tables covering the Bristol Channel, in that they now refer directly to Chart Datum as opposed to Height over Cill as in the past. Those of you sailing regularly past the Second Crossing to Sharpness etc need to aware that the cill height for Sharpness Dock is 0.5m ABOVE CD. Whilst this is of fundamental importance to commercial traffic working on mimimum UKC leisure users may well use predicted HW heights for their own restrictions/ limitations etc. Just a caution for those not aware.

 

[graham]

I think for most of us heights above CD will make it simpler to use.

Will have to remember to stop making the corrections now.

 

[matelot]

been using them for 20 years and never knew that. where's the cill at avonmouth?

 

[graham]

The Avonmouth figure used to be King Road so it was taken from Chart Datum anyway.

I think the book was confusing as it was with some places measured from CD others above lock cills .

If you used the Barry tables uncorrected they would give you 3.3 meters more water than CD. Certainly enough to ruin someones day /forums/images/graemlins/grin.gif

 

[matelot]

well I never! sloppiness on my part that I sailed in and out of barry endless times without knowing that. mind you in the channel you either are aground or have more than enough water in my experience

 

[graham]

To be honest how many of us ever do any tidal height calculations when sailing around the channel?I know I dont.

Once you have been somewhere a few times you know how many hours before or after HW you can get in. I usually ask the locals then mentally subtract 30 mins to be on the safe side.

 

[damo]

Me. All the time.

I want to know how much clearance if I'm crossing the Grounds, what depth I can anchor in on a falling tide, how much chain to put out for the rise of tide, calculating first and last lock times at Portishead.

There are some "holes" I anchor in from time to time when it is quite crucial to know how much the tide will fall /forums/images/graemlins/smile.gif

On saying all that, I give a good margin now, having discovered how much heights and times can vary from one tide product to another, and from prediction to actual.