Humber Blues-tide 'half a metre higher than forecast' frees stuck boat

Humber blues
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Remember the cruising couple that left their boat for a couple of drinks at the local pub and came back to find they'd anchored on a mudbank in the Humber River and were left high and dry? The worst news was they were to be stranded there, not until the next high tide, but until, according to the tidal charts, the 13th June. But sometimes you can be lucky.

Humber River Blues
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After a mere 10 days, volunteers from Humber Rescue launched an operation to rescue the stricken vessel at around 6pm last night after receiving information that the tide was running half-a-metre higher than predicted.

It was hoped this would allow the six-tonne yacht to float high enough to be towed off the mudbank.

A spokesperson for Humber Rescue said the operation 'was not without its scares' as the anchor chain from the yacht became wrapped around both of the rescue boat’s propellers leaving lifeboat volunteers with a challenge to free them.

Under the supervision of the yacht’s owner and with some careful towing, the vessel was released from the mudbank and taken into Brough Haven under her own power, escorted by some members of the yacht club.

Dave Roberts, Chairman, Trustee and Coxswain at Humber Rescue said: 'This was a great opportunity to get the yacht off the mudbank and back to where it belongs and everyone involved did a fantastic job especially when it came to releasing the anchor chain from our propellers.'

The two sailors had set sail from Brough but the incident brought their sailing adventure to a sudden halt. The pair waited for 12 hours until the next high tide but were unable to get off and called the inshore lifeboat Humber Rescue for help.

The lifeboat rescued them but couldn’t get the yacht off either, and after a second attempt on Monday decided it would have to wait, ironically, until Friday, June 13, when the tide should be high enough to lift the six-tonne yacht clear of the bar.

The Humber is well known for its shifting shipping channels and the lifeboat attends boats running aground on a 'fairly frequent' basis.

'It happens more of a weekend when people have time off, but it can happen at any time, ' said crewmember Phil Ramsden.

But there's a remaining question: Why was the tide running 'half-a-metre higher than predicted'? I thought these things were set in stone and I could rely on my tidal charts. Can anyone answer the question?
http://www.sail-world.com/122710