Reverse Thruster assist

[KoolAid]

You are correct on your thinking with this Unstuck. The only difference between a small setup and a big one is speed. Don't forget it needs to be a big enough setup to offset wind speed to make it worthwhile.

[D&P Powell]

I've been in the new G23 with it and it was cool...

Not that I would ever purchase one, but I am curious Mike - was it (or did it appear to be) as easy to use as they advertise?

[Ruger761]

I thought a lot about this when this thread first came out. A small child can hold onto the swim deck and push the boat in a circle. This tells me it would require very little thrust to move the boat. I thought about taping a ballast pump output hose onto my transom to see what would happen. Then playing with different size nozzles to see what kind of pressure would be generated. These are flow pumps, not pressure pumps, but it may work. You certainly wouldn't get the speed of the real ones, but I bet you could get decent parallel parking out of it. I imagined having 4 "thruster" ballast pumps, one running to each corner of the boat just below the water line and two momentary switches to power left and right or one of each. The whole system for a few hundred bucks.

I like where you are going with that idea. Sure would be a lot cheaper and cleaner as well. Would be interesting to see what kind of flow/pressure would be needed to generate enough thrust to push it around. Its likely going to be more than a standard ballast pump would push but I could be wrong. Haven't ever tried to quantify how much force is required to push a stern or bow around.

[MikeB313]

Not that I would ever purchase one, but I am curious Mike - was it (or did it appear to be) as easy to use as they advertise?

Yes, it is very easy to use. You can set it so it turns with the steering wheel and throttle. We had it setup that it would just turn on/off by touching a button on the touchscreen. You would just press and hold whatever arrow direction you wanted to go and the boat would spin in that direction.

[hcooperrn]

FWIW -- I contacted EZDrive and got a quote -- with their boat show incentives, you basically get all of the install and upgraded controls for free with a $2k discount, final price being $4995. Oof. Right in that spot that I'm not sure I want to spend that much without some testing with smaller pumps like Unstuck is thinking.

[IDBoating]

I thought a lot about this when this thread first came out. A small child can hold onto the swim deck and push the boat in a circle. This tells me it would require very little thrust to move the boat. I thought about taping a ballast pump output hose onto my transom to see what would happen. Then playing with different size nozzles to see what kind of pressure would be generated. These are flow pumps, not pressure pumps, but it may work. You certainly wouldn't get the speed of the real ones, but I bet you could get decent parallel parking out of it. I imagined having 4 "thruster" ballast pumps, one running to each corner of the boat just below the water line and two momentary switches to power left and right or one of each. The whole system for a few hundred bucks.

We are developing a thruster system, had this same idea, and we have experimented with this a LOT. We had the same expectations as you did, and indeed our early tests were pretty encouraging.

But then the real world reasserted itself. Aerator pumps are completely useless for this application, for example. The effective backpressure completely defeats them. That leaves pumps with positive displacement, in this world that's flexible vane impeller pumps like the Ballast Puppy and Ballast King. We created custom assemblies of single and multiple such pumps. After extensive testing, what we found was that under absolutely ideal conditions (dead flat water, dead calm wind) such an arrangement could rotate a wakeboat hull... very slowly. Far too slowly to be commercially useful. Add in any wave action, any current, or especially any wind and it's just useless. The wind is a huge problem because of the cross sectional area of today's deep wakeboat hulls. There's just so much surface area there for even a gentle breeze to work against.

Remember the law of conservation of energy? Ballast Kings draw about 20 amps, in a 12V system that's 240 watts. Most thrusters draw well over 100 amps, some are in the multiple hundreds. 100 amps is 1200 watts, 5X a Ballast King. Ultimately you are transferring power to the water to move the hull, and there's no free lunch here, so that power has to come from somewhere. There's nothing magical about using a pump vs. a typical external thruster's propeller, you still need to transfer enough power to move the load. And the load is a long hull with very large flat sides that resist sideways movement in the water while acting as great "sails" to the slightest breeze. Everything is working against you.

Thankfully, we do have a solution and it's in final R&D right now. I can't talk too much about it yet but for those manufacturers who want to offer thrusters, it will be the single best solution available.

But don't lose sight of the key principle here: This is ultimately a power problem, and a Ballast Puppy or Ballast King (or even multiples) just can't transfer enough power to get the job done. Trust me, we thought it was a great approach until the first breeze showed up. Then we couldn't even prevent the breeze from rotating the hull, must less make it rotate the direction we wanted or control it in any way. We really wanted it to work, but physics had other ideas. If someone tries this, it will end up being very embarrassing. We dropped it immediately when we realized it because we don't want to be the source of embarrassment for our customers.

[hcooperrn]

Good to know ID, thanks for the reply, and for saving me the frustration of playing with a bunch of pumps

Can I ask - do you have a rough ETA on time to market? If R&D is wrapping up, do you still need to find a manufacturer and supplier, meaning it could be a year or two out still?


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[IDBoating]

Good to know ID, thanks for the reply, and for saving me the frustration of playing with a bunch of pumps

Hey, don't let me slow you down on experiments!

Can I ask - do you have a rough ETA on time to market? If R&D is wrapping up, do you still need to find a manufacturer and supplier, meaning it could be a year or two out still?

We are our own manufacturer. As with most of our products, this will likely only be offered to boat manufacturers for inclusion on new boats. A retrofit system might be possible but we're not set up to support end users. This will be something you have to buy a new boat to enjoy, sorry. As for timing, this industry generally commits to new products by January for the production year that starts the following June-July. However, we do have some folks interested in a mid-year release which often happens around December, just in time for boat show season, so you might start seeing these (and some other really cool stuff we're doing) in about 12 months at January-February 2021 boat shows.

There are retrofit thrusters available out there, but watch out for their current requirements (as noted above). A typical 1-2 battery setup isn't going to work very well. Even the big alternators are generally only good to about 220 amps; that might be enough for some of the smaller thrusters but would require an intelligent load shedding switch so that the huge current sink wouldn't draw down the main bus going to the ECU, helm electronics, etc. It would suck to have your engine and helm reset every time you turned on the thruster.

[IDBoating]

The only difference between a small setup and a big one is speed. Don't forget it needs to be a big enough setup to offset wind speed to make it worthwhile.

As usual, KoolAid is right on target here. The one thing I'd add (really, repeat) is that "big enough" is WAY bigger than anyone thinks it needs to be. I could show you photos of the setups we tried... we were spinning boats like crazy, and for fun one time we used a system to power a 12 foot aluminum fishing boat! We weren't going very fast but it definitely was moving on its own.

Then the wind and water started acting on the hulls, and it was O-VER. We wanted it to work so badly, we kept telling ourselves we could overcome it, but it's amazing how much impact the wind has on today's high freeboard wakeboats. Plus, the part of the hull that is underwater is strongly resisting rotation, AND is reactive to any waves or current. I saw UnStuck's comment about a small child moving a boat, funny thing is that's exactly the train of thought that got us to try this too. But then you start actually measuring the forces involved and two things become apparent very quickly: Kids can impart more force than you think, and pumps impart less. Keep in mind that the child has a solid reference point (like a dock) while the pump is just shooting water. The former is a far more efficient power transfer mechanism than the latter. To extrapolate that a bit: Which would be faster for you, as an adult, while standing on the swim platform: Spin the boat by pushing on a dock, or using an oar/paddle?

[BrentP]

I think I want to go work for ID...........


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[IDBoating]

I think I want to go work for ID...........

That's a very nice complement, thank you! We do have a lot of fun, though at times it's frustrating (like with these thrusters). It's a really good feeling when we grind through a challenge and have a great product at the end that makes boats better for manufacturers and customers.

[UNSTUCK]

This is fine... I actually really enjoy always yelling at my kids to jump in the water and push us to the dock. What can I say, my kids are my dock stars!

My other thought was to mount a pump to the engine accessory drive. This system would be much harder to do, but doable. It would need to have a clutch on the pump, similar to an A/C compressor clutch. You'd want to tune the computer to bump up the idle speed when engaged. Then you would need the same diverter valves and plumbing as the kits already out there. Likely not cost effective or really doable for the average joe. In general I wonder about the lag in operation with the water pump thrust systems VS the propeller systems which should be near instant.

For the manufacturers, I think they should consider a PTO on the transmission. Turn the boat into a water truck!

And yes, I also want a job.

[IDBoating]

I love that you folks are thinking about such things! Let me know if you get tired of me commenting on them....

My other thought was to mount a pump to the engine accessory drive. This system would be much harder to do, but doable. It would need to have a clutch on the pump, similar to an A/C compressor clutch. Then you would need the same diverter valves and plumbing as the kits already out there.

Yep, been there, tried that. The two major problems with this concept are:

1) Nobody makes an SAE J1171 certified clutch. Marine engine spaces are required to have electrical equipment certified to J1171, which means they will not ignite fuel vapors. This is one of the reasons you don't just slap automotive starters and alternators on marine engines. Clutches are available but they are designed to be used in automotive engine spaces which are ventilated.

2) Those "diverter valves" are nightmares of unreliability and maintenance. Check out Centurion's history with their RAMFill system, which is based on them. Basically what happens is folks use large gate-type valves meant for the RV industry (think black water dump valves). Those valves are so unreliable that their manufacturers specifically incorporate manual overrides in them so you can insert a wrench and manually open/close them when they fail. Not very reassuring to have 3-4 INCH DIAMETER valves letting water into your boat that might jam up and be unworkable! For the present case, it's just not commercially viable to base a product on them. OK, maybe some companies would be OK with that, but we're not.

You'd want to tune the computer to bump up the idle speed when engaged.

Another great observation, good for you! Now, think about this: What happens if you want to engage the side thruster when the main prop is turning (e.g. you actually WANT some forward or reverse thrust)? That's not an unusual situation, but do you really want something overriding YOUR choice of forward/reverse throttle in that circumstance? No? Then what happens when the operator gives the system conflicting commands... which one wins out? We're not training fighter pilots here, we have to design for the typical "weekend warrior" that might be several deep into a six-pack at the end of the day. A nice surge of forward/reverse throttle at the wrong time sounds like a lawsuit waiting to happen. No thanks!

I wonder about the lag in operation with the water pump thrust systems

This is the one thing that is NOT a problem.

[hcooperrn]

Curious, just how much flow is needed to overcome a breeze? I've seen the jet thruster from Holland Marine, and to the conservation of energy point, that's a lot of amps and moves the boat quite well. Does it have to be that much force?

Or, is there enough flow say, through our cooling impellers at idle, that solenoid valves could direct a strong enough jet to one side or another? I wouldn't bypass the engine cooling, maybe just a bypass before going out the manifold -- they wouldn't overheat too quickly would they? Or just add a separate pump as Unstuck suggests?

I'm nervous about the EZ Drive solution for one main reason (aside from cost) -- 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 -- I can't find a good picture of one that's installed with clear enough paths?

[Bamer]

Curious, just how much flow is needed to overcome a breeze? I've seen the jet thruster from Holland Marine, and to the conservation of energy point, that's a lot of amps and moves the boat quite well. Does it have to be that much force?

Or, is there enough flow say, through our cooling impellers at idle, that solenoid valves could direct a strong enough jet to one side or another? I wouldn't bypass the engine cooling, maybe just a bypass before going out the manifold -- they wouldn't overheat too quickly would they? Or just add a separate pump as Unstuck suggests?

I'm nervous about the EZ Drive solution for one main reason (aside from cost) -- 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 -- I can't find a good picture of one that's installed with clear enough paths?

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. So I believe my calculation and assumptions are reasonable.

bottom line....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....


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