4" Trevs Subbie dredge.

[principedeleon]

What im thinking of doing Jason is... i dont know if it makes much a difference but instead of using a bent inlet which is basically smaller then the hose diameter.. is bending the hose on top of the nozzle instead of bending a piece of pipe.


The difference from this and a jet log is that the suction nozzle haves a bent which you can direct the jet nozzle straight down the pipe. .

While on a jet log with the lowest angle you will always force the jet nozzle to the side walls.

 

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[Jason in Enid]

can you draw it out? I'm having trouble picturing your plan.

 

[principedeleon]

Is like cutting the suction nozzle inlet pipe like 3 inches before entering the nozzle.

Now the hardest part is in bending the hose and making it stay bend. .

But im thinking of welding a piece of pipe to feed the hose through to act as a support for the inlet hose.

This route just seems more simple with less connections just straight forward. .
In a future if it becomes a problem ill change the inlet pipe in metal but for testing practice ill try to make it as simple as possible.

 

[principedeleon]

Hii everyone. Ii just got back from the river. .

and the suction got wayyyyy better..
it was sucking harder even in lower rpms.
I was surprised.

Now ima have to build the inlet pipe on the suction nozzle in the same diameter to try not get any lost ..

Thanks everyone..
When i have the finished dredge i will post pictures.

 

[Timberdoodle]

Good to hear P.
You asked about the comparison of a suction nozzle vs a log jet.
The suction nozzle has a jet that is centered and directed into the flow- yes this is a better jet configuration.
The log jet has an angled jet which increases turbulence losses but in reality is always considered a stronger jet in operation.
The real difference in strength comes down to where they are located in the hose system. Let's say for comparison that good suction flow speed in a hose is 10ft per second.

A suction nozzle must force the suctioned flow volume combined with the injected flow volume of the jet down a long stretch of hose to the sluice box. To get 10fps of suction flow the total flow speed would have to be increased to accommodate the injected flow volume (5 fps) and the total flow speed would therefore have to increase to 15fps which takes energy and has more friction losses so even with a centered jet the overall design requires more power.
A log jet has very little hose if any after the jet so the losses incurred with increasing the flow volume after the jet have very little effect. So it's not a better designed jet as much as where it is placed.

As you know there are many other factors to consider for choosing a style of jet. If wanting to improve suction strength and allow for some hose settling, I would put the jet about 5ft in front of the sluice (mid-jet) I would also build a dual, tri, quad etc.. anything to improve performance of the off-center log jet.

 

[principedeleon]

Okay .. thanks for explaining this i would always keep this in mind even tho. .
I dont think i would return to a surface dredge. .
Im in love with the subbies. .

Im getting ready to run a 4" with a engine that fits in a grocery bag.
It cant get any better then this. xD..

 

[jsurddy]

What im thinking of doing Jason is... i dont know if it makes much a difference but instead of using a bent inlet which is basically smaller then the hose diameter.. is bending the hose on top of the nozzle instead of bending a piece of pipe.


The difference from this and a jet log is that the suction nozzle haves a bent which you can direct the jet nozzle straight down the pipe. .

While on a jet log with the lowest angle you will always force the jet nozzle to the side walls.

That 180 degree bent pipe on the suction nozzle should have the same diameter as the flexible hose that is feeding it. It looks smaller because the hose is so much thicker than the metal tubing. On the contrary not all nozzles are the same, so maybe you’re referring to one i havent seen before.

 

[principedeleon]

I dont know i never seen one in person. .in the pictures it looks that way. But i made mines the same size as the inlet.

It works okay but when i dredge down past 3 feet i feel a suction lost.
I believe the 3/4" jet is too large and im thinking of trying it with a 5/8" .

Maybe thats the correct sizing for best suction.