Aground off West Mersea

[NUTMEG]

Had a great day out yesterday, caught the ebb from Lawling Creek, fry up off of Osea Is then a good sail round the Nass to lunch at WMYC. All went well until we entered Mersea Fleet. Got stuck fast an hour before low water on the bank to stbd of the channel. The chart plotter showed us smack in the deep water, as did Navionics on two iPhones. But clearly the channel has shifted. Depth showed 1.5m just before we grounded. My question is how is one supposed to know when channels move?

Still had a great day, went ashore in the tender and sailed back in the dark, first time ever. Not another sailor out, just a few fishermen more insane then us!

 

[MoodySabre]

Well done nevertheless

I always follow the buoyage in, leave the packing shed to Starboard but stay in the moorings - but I wouldn't be there near low water.

No doubt Tillergirl will explain all.....

 

[tillergirl]

Ah yes!

First chatting to the Imray people last summer I was told that the last UKHO survey of this area was the 1970's. That's the best data they have. So any chart starts from being that out of date even if having a recent publication date. Imray have used some of my data in their charts - that's better than 1970's data but of course I am using amateur equipment and I have only done Mersea Quarters and not further in. Colin and I were specifically asked for coordinates of the buoyage in the Quarters and the North and South Channels last year and when we sent them they didn't fit too well on the 1970's plot. Hence the chartlets on my Web site as I went back and trundled over the area. If you have access to an Imray chart covering Bradwell Creek or the Ray Sand you can see the discontinuity between surveys.

Second, there wasn't any GPS in the 70's and the charts were drawn to a different datum - not a great difference but certainly enough in the narrow confines of Mersea Fleet.

Third, there is a simple rule in West Mersea - if there ain't a mooring, there ain't no water.

Fourth, Roger is right, Thornfleet is best for water and width - that's leaving the Packing Shed to starboard on the way in. At LW springs most of the small yachts in Mersea Fleet further in are touching the bottom or v close to so doing. In the season further in the minefield (where all the ribs are moored) is just that, a minefield of moorings, most of them designed for ribs.

Fifth, it is getting a little shallower I think in Mersea Fleet.

So I think we can conclude that it was inevitable and not operator error! Glad you had a good time.

 

[LittleSister]

My question is how is one supposed to know when channels move?

As one who has been caught out on a number of occasions, I feel qualified to offer the following advice.

You'll probably never know when channels move (unless you get prior warning from Tillergirl or other local), but all you need to know is that channels in mud and sand will move over time, and rely less on where a chart claims the channel was some (often many) years ago, and more on your depth sounder, the appearance of the water surface (if you can see it) to judge the flow, and general sense of self(or dignity!)-preservation. The detailed position of mud, sand and shingle areas' channels is what Dick Cheney would call a 'known unknown'!

Sounds like you enjoyed a great day, though!

 

[FullCircle]

Having run aground at midnight in the inflatable not more than 10 metres from our boat floating on a visitor mooring, I can assure you id do get a bit shallow!
Pleased you had a grand time.

Who made your thermals?

 

[NUTMEG]

Thanks all...

... I feel better now! It was a great sail with two new experiences, which is what it is all about. Sailing back in the dark was magical. A silver band of moonlight on the water, the stuff dreams are made of.

No thermals, just lots of layers, it was bitterly cold, although I did light the heater on the final run into Lawling Creek.

Film on the blog very soon if nothing else to do!

Steve