Dredge question

mmayer813

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Apr 5, 2022
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OK, here is what I woukd like to do.....need advice. I would like to move sand.....lots of it around my dock to gain some depth. I would like to build an inexpensive PVC dredge and use my jetski as the pump. I have plenty of 4" firehouse to attach to the ski, but I don't really know much about building a suction dredge. Can anyone point me to a design, or provide guidance? Thanks.
 
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russau

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May 29, 2005
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Well for one , DONT USE that pump to run sand through ! as is lead use to understand . Running your J. ski pump to use as the source for your high pressure water to make a nozzle work WILL murky up the water with fine sand and ruin your pump seals quickly !!!!! You can rent a big pump to get that job done a lot faster and more economical ! it sounds like you have a LOT of sand to move and you'll want to move it out of the water and to the bank to get it out of your way. There are plan to make one on one of these forums and the you'll want to run some bigger PVC line to carry that sand away. I'm assuming you'll be busy for sometime doing this . I'll bet this location is a beach area in salt water ? If so , remember that salt will eat up aluminum if you don't flush it out EVERYDAY! This will be a yearly task to do if your location is where I think you are. The waves will move more sand into and around your dock again in time. Good luck !
 
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mmayer813

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As I understand it, I would use the ski as source water only to supply pressure to the venturi nozzle. The ski would be about 50ft away from where I want to pull sand out, and then deposit even further from the ski. This is a very clean fresh water lake, pretty much all sand, no rocks.Maybe I am missing something?
 
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Bonaro

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Im not sure of the pressure or volume of water that a jet ski would put out but in concept it should work. The ski output would have to go thru a venturi and operate like a dredge jet. I would be pretty certain you could build a 6" suction dredge and that would move a lot of sand in a hurry
 
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mmayer813

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Im not sure of the pressure or volume of water that a jet ski would put out but in concept it should work. The ski output would have to go thru a venturi and operate like a dredge jet. I would be pretty certain you could build a 6" suction dredge and that would move a lot of sand in a hurry
The ski is 250hp, so volume and pressure should be more than enough. I have 4" fire hose to work with from ski to suction unit, and from suction unit to the area for deposit. What I am not clear on, is how to build the suction unit....nozzle size, angles.....etc.
 

Reed Lukens

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Here's a thread on it -
 

ratled

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Fire hose as a pressure hose is a poor choice for this application as it kinks easily. Since this is a one and done op for you Russ's suggestion of a trash pump maybe the easiest and cheapest in the long run. If you have to build a sand pump dredge consider buying a commercial jet or suction nozzle. You are still going to need hard suction hose to both suck up the sand and move it to where where you want it.

Lastly thats a lot of waste material you have to deal with and there are whole host of EPA issues you just created. Simply pumping up on the bank and letting the water go back in can get real expensive real quick from the EPA and whatever water agencies have a stake in the lake
 

RTR

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Instead of sucking it up how about blowing it away ? If a "prop driven" boat is available(make a mailbox) you could tie the boat to the dock and let the "Mailbox" remover the sand.:dontknow:
>>
 

russau

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That mail box like Mel Fisher used in the ocean had a current to blow that suit cloud away from them after awhile of non-use. Using that system in a still lake or pond would cloud up in no time and it'll be not till the next day he could get back in ! . I still say use as big of suction device as you can afford and pump that sand /silt to the bank to get it out of your way! Mother Nature will put it back in her own time UNFOURTUNATLY !
 

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