Reverse Thruster assist

[hcooperrn]

40-80lbs of thrust to get 6000lbs moving 2-4mph.

Is that 80lbs net thrust? Meaning if something is putting out 20psi, I need 4 sq in of area at that pressure?

Trying to go the other direction -- how much water volume/flow/pressure is needed. If 2-3 jabscos aren't enough, is the engine-driven impeller (at idle) closer, or still not in the ballpark? Is there a middle ground before getting to the heavy-duty jet thrusters (which rely on a 480amp motor, I get that).

When you get up around 4-500 amps with 3.5" inlets, we get the great videos of boats spinning in circles, just not sure that's what is fully needed? Or is it? IDBoating, is that the conclusion you reached eventually, it just takes something that big?

Better way to say it maybe -- would a 200amp/2.5" create enough thrust to overcome a breeze? 100amp/1.5"? Just wondering what minimum viable would be.

I don't quite have the expendable income to do a bunch of testing unfortunately, and I get in a lot of trouble when I drill holes in the boat, so hoping to only have to do it once...

If I'm just way out of my element on the math on this, let me know, physics in college was a long time ago and I was a bio major.

[Bamer]

Is that 80lbs net thrust? Meaning if something is putting out 20psi, I need 4 sq in of area at that pressure?


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I too am past my knowledge expertise, but just applying a basic engineering approach i would assume 20psi over 4sq inches equals 80lbs of force. Doing unit analysis, the sq inches cancels leaving lbs as the resulting unit. In any case, check out this web calculator. Looks like it is what you are looking for.....


https://www.giantpumps.com/technical-info/nozzle-chart


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[IDBoating]

I did a quick force = mass*acceleration calculation. I made several assumptions and came up with that you need somewhere in the ballpark of 40-80lbs of thrust to get 6000lbs moving 2-4mph.....so I looked at trolling motors and that’s actually the thrust range most trolling motors are rated at.

Indeed. And small-scale aftermarket thrusters are often rated around 60-80 pounds of thrust. So your numbers are definitely in the ballpark.

I believe You need some pretty serious power and that’s why these thrusters use a couple 100amps at 12V....anything that’s only using a few amps most likely will not work....

The key is actual work delivered, which is commonly measured in watts (volts * amps) or horsepower (~750 watts per HP). In the ~13.8VDC environment of wakeboats, one horsepower is roughly (750W / 13.8V =) 55 amps, presuming 100% efficiency. Even the Ballast Kings are starting to sound kinda wimpy, eh? They are rated at 20 amps, which means at peak power they are (20 / 55 =) about 1/3 HP.

Now compare that to the aftermarket thrusters that pull, say, 200 amps. That's 10X the Ballast King. It's pretty clear you're not going to get typical thruster performance from ballast pumps when they're delivering 1/10th the *power* to the water. What are you going to do, parallel 10-12 of them? The plumbing losses alone make that hopeless.

But there IS a way. And we'll have it ready midyear. {grin}

[IDBoating]

I just can't quite see how it can be tucked up enough to avoid messing up the wake, while not getting blocked by the platform brackets and the FAE

Agreed, that's something we hate about them too. Just another fragile contraption glommed on under the swim platform. Looks ugly, looks fragile, and can't help but disrupt water flow right exactly where you want the water flow to be smooth.

There is a solution... and it doesn't require "tunnels" through the hull either (like some yachts use). Those are manufacturing and efficiency nightmares, and it gets really frustrating when your stern is heavily ballasted and a forward tunnel suddenly isn't fully submerged anymore. "Whaddya mean, my thruster doesn't work when I'm ballasted?!? This is a WAKEBOAT!!!"

[hcooperrn]

But there IS a way. And we'll have it ready midyear. {grin}

Ok, I'll be patient, pins and needles until then (and fingers crossed on the ability to retrofit so we don't have to steal IP and replicate )

[IDBoating]

Retrofit will require some custom mechanical parts, a way to interface to the controlling electronics, plus the normal components common to every install. It won't be very practical for the typical DIY'er. But we'll see... we're open to comments once we announce.

[Bamer]

This trolling motor might be feasible to mount to swim deck/boat. 55lbs thrust, <$700.......if you could figure out mounting/clearance, I’d bet it move the boat around.....

MinnKota EM 55 Engine Mounted Trolling Motor (55lbs of Thrust) https://www.amazon.com/dp/B000KOVPW8..._XZnlEb19FNZB1


Or

MinnKota Riptide EM 55 Engine Mounted Trolling Motor (55lbs Thrust) https://www.amazon.com/dp/B000EQU70I..._.kolEbA318CZZ







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[UNSTUCK]

But there IS a way. And we'll have it ready midyear. {grin}

Ahhhh haaaaaa! I know what you guys came up with and it’s brilliant! You couldn’t overcome the breeze so you used it to your advantage. Forget about all this thruster nonsense. You guys made a retractable mast and sail that mounts to the stern of the boat. Come into the marina, up goes the mast, breeze fills the sail and slides you sideways into the dock.

[Zackdogg]

This trolling motor might be feasible to mount to swim deck/boat. 55lbs thrust, <$700.......if you could figure out mounting/clearance, I’d bet it move the boat around.....

MinnKota EM 55 Engine Mounted Trolling Motor (55lbs of Thrust) https://www.amazon.com/dp/B000KOVPW8..._XZnlEb19FNZB1


Or

MinnKota Riptide EM 55 Engine Mounted Trolling Motor (55lbs Thrust) https://www.amazon.com/dp/B000EQU70I..._.kolEbA318CZZ







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There’s a dude on wakegarage that did exactly that. Sounded like he had it working pretty ok, last I saw, but I haven’t looked at that thread in awhile.


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[IDBoating]

Ahhhh haaaaaa! I know what you guys came up with and it’s brilliant! You couldn’t overcome the breeze so you used it to your advantage. Forget about all this thruster nonsense. You guys made a retractable mast and sail that mounts to the stern of the boat. Come into the marina, up goes the mast, breeze fills the sail and slides you sideways into the dock.

Yeah, now if we could just figure how to make it work when the breeze is blowing the wrong way.

If we push this concept far enough, we'll all be selling our wakeboats and buying sailboats....

[hcooperrn]

You guys made a retractable mast and sail that mounts to the stern of the boat.

Would that make us a sailboat and give us right-of-way over everybody else at the ramp? That could be almost as good...

Pins and needles until IDBoating can give us more, it may be hard to retrofit, just need some more ideas to find something worth trying.

[IDBoating]

Not impossible to retrofit, but could be awkward and a bit pricey to put it on a boat that didn't start with it. More details later this year....

[Bamer]

Not impossible to retrofit, but could be awkward and a bit pricey to put it on a boat that didn't start with it. More details later this year....

Will you post the solution on here when it’s announced?


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[IDBoating]

Will you post the solution on here when it’s announced?

You bet!

[VMS]

I've been designing and testing my own system this summer for my ZX5, and have most of it all worked out. The addition of a stern thruster changed every aspect on the water. Yes, it's a godsend when maneuvering, docking, or trailering in a crowed, windy, or tight rock ridden environment, but just being able to kick the stern around for a newbie or someone taking too long to yell 'HIT IT' made my day as the driver much more pleasant. No more go arounds!

My company currently designs and builds equipment for Oil Tankers, and systems to remove oil from water in the Oil & Gas industry, but I've started a new company for this venture. We are targeting late Spring 2021, and at a reasonable price. Not the $10K my local Tige dealer quoted me to install the 'EZ'!

The system is small, and will fit on a stern that offers very little real estate. It fits right between the underwater LED and swim platform bracket on my ZX5. If you're handy, you should be able to install yourself. Shoot, I installed by simply enlarging the existing hull penetration for the wire used for my surf plate actuators. No other holes added!

Our compact 'High Tech' unit, which is literally a beautiful work of art and pleasing to the eye, could also be adapted as a bow thruster with a little work, and something that we'll be designing after launch of the stern thruster. With a little mold modification, it can be nicely nested into the hull brake on new builds, or if your not afraid to do a bit of notching and fiberglass work on the bow brake, you could add to your boat. I personally am not inclined to hack my $170K ride just yet!

The Facts:
You do need high thrust, at least 50 pounds, but preferably above 70 for the ZX5. This requires a huge current draw, and very large cables (3/0 or 4/0) to move the current required from the 12 volts. Think upwards of 210 plus amps for about 50 pounds of thrust! Our system will not require such. We will have multiple thrust options from 44 pounds with our very unique high tech 5" diameter x 4" thruster, 77 pounds on the compact 5" x 8" unit, and over 105 pounds on the slightly less compact unit. Standard remote control for all options so you can move around the boat to tie up if needed!

Pricing and design will allow easy installation of a thruster on each side of the boat if you're looking for insane thrust, or want to use the smaller High Tech Work of Art Thruster, and need more thrust than one can provide.

Stay tuned!