Eddies in the solent...

[andrewhopkins]

Out for two lovely days on Friday and Saturday around Yarmouth and Cowes. Sunshine and warm too, the only downside was a lack of wind that made the water like a mirror in the Solent.

Motoring along under autopilot I kept noticing all the unusually paterned eddies between cowes and yarmouth.

What's causing them then ? I can understand some around hurst castle et al but why in the middle of the channel ?

Is it rocks/obstructions on the sea bed or perhaps a giant squid ?

 

[Twister_Ken]

Uneven bottom is part of the answer. But also the IOW coast is bendy, so the tidal flow gets squeezed out into the deep water channel, and then can spread back inshore. And the tidal gradient (faster in deep water, slower in shallower water), means that there is friction between slower and faster water at many points.

And then of course there are the real eddies . We anchored in Totland Bay (wide bay one to the east of Alum Bay) on Saturday in a slight east going current, while half a mile away, the tide was steaming west at a couple of knots.

 

[Eudorajab]

Youve seen him too have you ?

 

[oldharry]

Bad news for HMCG if he has arrived down here!

Seriously though, studying where the eddies and back currents are at strategic points in the Solent at different states of the tide is not only fascinating, but can make a big difference when you need to get home, but have missed your tide.

Classic example: after overnighting in Keyhaven before going on up channel outside the Island, someone(not a million miles away) overslept and was late setting out to clear the Hurst and the Needles. The infamous Trap supplied a neat West Going current close inshore to carry me clear of the narrows. Crossing to the Island side gave me just half a knot head current towards Alum Bay where another eddy carried me close inshore out to the Needles. Alum to Needles light was covered in about the same time as it took to round the Light and find the east stream.

Another yacht clearing Hurst about the same time was still a long way back up the channel as we rounded the Needles....