DIY Dredging Ideas?

savageseadog

savageseadog

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Has anyone done any dredging to deepen their own berth? I was thinking of doing some dredging in a mud situation, not drying and wondered if anyone was as crazy as me and had tried anything.
I was thinking of using a large diesel powered diaphragm pump, 4in or so like a vacuum cleaner and a long discharge hose over the marina cill, would it work? and would other types of pump work? I'm not sure about permissions etc, perhaps some jobsworth will come along and say I need a license to discharge etc, who knows.
 
The approach to the canal here is dredged every few years, the method is crude and involves a poweful boat pulling a trawler type dredge along the bottom on a falling tide. The hope is that the disturbed silt will settle elswhere, it usually comes back again with the next southerly gale. In Scotland you need SEPA (Scottish Environmental Protection Agency) to do anything like this even to move stones on the foreshore, you are very unlikely to be given permission for anything, it is much easier to say 'no'. The most effective method for small scale dredging where access is available is to pull it out with a long jib tracked digger, they operate effectively out to about 10m. from where they stand, but then you need both SEPA permission to take it out and again to dump it including paying land fill charges and tax. It is illegal to just use it to fill a hole but if you can find someone who wants it then you can sell it as 'fill'
I think that you would need a very powerful pump to clear a significant quantity of silt but the sand dredgers in Lough Neagh and elsewhere can fill the barge in no time but their equipment is very specialised (and expensive).
Good Luck, but the beaureaucrats (sic) will be even harder to shift than the mud.
 
One of the marinas on the Medway uses an "agitator" - which is a floating box, twin props for positioning and a vertical screw for er, agitating. The idea is that the slurry stirred up is then circulated around the basin then over the cill by a carefully planned arrangement of boats running engines in gear. The slurry then settled, blocking the channel on creek next door so port authority has required the block to be cleared using - a dredger probably. There used to be a song :"Don't put your muck in our dustbin, our dustbin's full" but if you only have a bit of muck then it might be OK. Done officially there are bound to be objections, I'd have thought.
 
Perhaps a pump working in the reverse fashion, blowing it away with water taken in and discharged from the berth might be easier than having to collect spoil, and would spread the mud around.
Here on the Hamble any work on the riverbed is 'affecting the indigenous lugworm and ragworm habitat' I've heard, and if a marina berth, highly unlikely to be allowed.


And what about the seahorse colony.......coat hat!!

ianat182
 
it must be rather annoying that one is not allowed to restore the 'status quo extat', and remove adventitious mud, with a court of enquiry or a licence.

Can you test run your engine for a while on a strong ebb ?
 
How about a diver and an 'airlift'?An airlift being a longish(2m plus) solid walled tube with a compressed air inlet at the bottom.The rising air in the tube causes a suction at the tube mouth which will vacume sand,mud etc,for the current to carry away.As far as permission is concerned,I found this quote on this forum,'It is sometimes easier to get forgivness than permission'.If you wait for the authorities to do something,you will get more depth more quickly by waiting for rising sea levels.At least, IMHO, as far as the Gwynedd maritine department is concerned.
Cheers
 
The airlift idea is good and could be done without diving but I would have to do it at high tide otherwise the depth wouldn't be sufficient.
 
All you can really get away with is running your engine in gear.

Sadly the whole dredging thing is very tightly controlled now by the Marine Management Organisation (MMO) -ex DEFRA etc (who interestingly, have apparently taken 4 years + to invoice various companies for dredging licences - no wonder the countries going down the pan).

Licences are enforced quite rigourously at times, which IMHO is ridiculous as it's nature that bought the silt etc in in the first place, yet you then have to pay very large sums of money just to put it back again to where it came from. Understandable if you are removing landfill or whatever for large capital projects, but for maintenance it seems like just another tax.
You will get shopped by some monkey if you do anything else - one marina got reported for an 'illeagal' mud dump when their dredger wasn't even operational, just because an area of mud appeared on a beach!

Suction definately works, but you'll be surprised by the amount of it required (and a pump that can handle solids) and also a cutter unit as the mud will be rock hard a few feet down - if going that deep). That's why dredging companies charge so much - speciallist equipment to do it well!
 
I would have thought that running the engine in gear will only have an effect at low water?

If so, is there not a risk of ingesting a lot of mud into the cooling system and clogging it up? Fine suspended silt would probably go straight through the average inlet strainer but block the passges in the heat exchanger. Also it might cause excess wear on the pump impellor?

Perhaps I am being alarmist, but we have had problems with our club launch when it has been used in very shallow water.
 
Not in my experience. If there is enough water to float the boat above the mud all the silt is blown away from the engine intake.
Why would you be interested in anything other then low water, depth won't be a problem any other time!
 
Dredging berths on the Blackwater Estuary is undertaken using a small motor driven pump and old fire hose.

The suction is placed in the middle of the river and the hose used to cut through the mud which is then lifted and carried away by the tide.

For some reason it seems to work better on the rising rather than falling tide.

The pump is run even at low water, so long as the suction is covered, and the water from the hose acts as a cutting lance.

Very effective in my experience as an observer.
 
Mariner69 said:
Dredging berths on the Blackwater Estuary is undertaken using a small motor driven pump and old fire hose.

The suction is placed in the middle of the river and the hose used to cut through the mud which is then lifted and carried away by the tide.

For some reason it seems to work better on the rising rather than falling tide.

The pump is run even at low water, so long as the suction is covered, and the water from the hose acts as a cutting lance.

Very effective in my experience as an observer.
Click to expand...

What sort of pump is it please? Permission?
 
From what I can see it is an ordinary old fire pump type of unit. Bit like the old fashioned 'Downton Pumps' that the fire brigade used. But any pump will work since you are only pumping water to power the hose.

Trust that helps.
 
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