zebedee41
Member
Should try crowd funding to get rid of the mud and bye the lease
Any news from Watchet?
- Thread starter PCUK
- Start date
NotBirdseye
Well-known member
Would still need someone to then manage the harbor...
graham
Well-known member
If it was a one off event there wouldn't be a problem but
Watchet would need an annual major dredge plus maintainance
through out the year to keep even most of the marina clear.
Watchet would need an annual major dredge plus maintainance
through out the year to keep even most of the marina clear.
NotBirdseye
Well-known member
As long as it had regular maintenance it wouldn't need an annual dredge at all.
bitbaltic
Well-known member
It needs digging out and then a system to keep the entire water column (surface to marina bed) agitated when the sill is up. The settling velocity of the mud is very low, so as long as the water is kept moving (however slightly) it will not silt up again. I wonder if those air bubbler thingies they have in Penarth/the bay would do it. Still there is a cost to running those twice every day for ever.
graham
Well-known member
The water in Barry Harbour is constantly moving from tide and wind and wave effect .South or South Easterly winds can produce large breaking seas coming into the harbour .
It still requires a major dredge from a ship sized dredger (UKD Orca)annually to maintain the depth .
It still requires a major dredge from a ship sized dredger (UKD Orca)annually to maintain the depth .
Allan
Well-known member
In another thread on here I detailed a plan to do exactly what Bitbaltic says, using the water from the stream. Relatively cheap, sustainable and practical.
Allan
Allan
Birdseye
Well-known member
Not sure about that. One of our universities or renamed tec colleges, did a project on the harbour mud and founf that every tide was bringing in around 30 tonnes. Sure it doesnt settle completely but it doesnt need to do so. Even before the marina was built, Watched silted up. The now diverted stream made a cut through the silt but didnt get rid of it so my bilge keeler would leave two furrows in the harbour "floor" if I came in after mid tide.
The marina design was simply wrong.
PCUK
Well-known member
It's taken 18 years to get in this state. If it was dug out again a proper maintenance programme would keep it clean. But it needs that initial investment to get started again.
sarabande
Well-known member
At 1.3 tonnes of silt per metrecube, that is 23 metrecube per day, or around 8400 m3 each year. Or very approximately raising the entire sea bed by 1.6m each year.
You don't have the citation to the research handy, do you ?
SaltIre
Well-known member
PlumDuff's post was per tide - not per day. So should your 1.6m be doubled to 3.2m? Increasing the seabed by over 10 feet per annum does seem problematic.
Birdseye
Well-known member
No. The research was quoted to me by the marina manager at Watchet and it much have been 10 years ago. But its likely if you think about it. Sea comes in carrying the silt as we see all the time in the Severn. Over the six hours that the sea level is higher than the cill, the silt starts to settle down and the water that flows out over the cill has less silt in it than it had when it flowed in. The outflow isnt of a speed that would stir up silt from the bottom and the marina has no ability to flush the basin in the way that happened before the cill was built. I would have thought it inevitable that mud would build up almost to cill down level.
Sure it could be dredged out though I believe they have environmental restrictions on what they can do. But dredging is expensive and marina income isnt that great.
The marina is a dead duck really. No way can marina income pay both for dredging and the maintenance of such large exposed harbour walls.
Snoopy463
Well-known member
The low impact dredging does seem to be having some effect, albeit slowly. Are they raising the cill as per usual? If so, depending upon the rate of sedimentation, x tons will be added each tide. If the cill were to be discarded, at least the ebb would take out most of what was brought in by the flood tide. Watchet would then become a mud berth marina, like many on the east coast. No problem in sitting in soft mud to your waterline. Keep the minimal dredging to keep 6 feet of mud above bedrock and even fin keelers will be happy. Simples!
bitbaltic
Well-known member
There will always be more silt in the water column than will settle each time the cill is shut (that’s why the water stays brown). Therefore the only thing that matters is the velocit(ies) of water at the marina bed versus the settling velocit(ies) of the particle size distribution of the mud and silt in the water column. That will govern the rate of sedimentation and nothing else.
as others have pointed out the figures you were given by the marina are not realistic.
NotBirdseye
Well-known member
I don't think the numbers matter that much at the moment. We know that Watchet is more affected than most other harbours and therefore it is tougher to keep the mud out. So I think we can cut Plum some slack.
Someone probably put a decimal point in the wrong place! (or didn't convert properly from imperial to metric...).
Sneds
Well-known member
Anyhow. Is some bugger going to sort it out?
SaltIre
Well-known member
I've added this thread to my watch list and will watchet with interest.
NotBirdseye
Well-known member
@SaltIre the cloak room is that way...
SaltIre
Well-known member
I've added this thread to my watch list and will watchet with interest.
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PCUK
Well-known member
If Watchet became an official mud berth marina with fees Significantly reduced to reflect the change then it is possible that take-up would increase sufficiently to make it profitable.
