Boat steering 2

[mingki]

Hi I am installing these motors to the backside of my boat for propulsion and also for steering using dual motor controller.

My boat is this.

The steering mechanism is like this.

The motors are all fixed on my boat and I want to steer the boat by proportionally controlling each motors rotation.
Is this feasible in reality or should I just go for normal outboard steering mechanism which is just rotating the whole outboard?
The motor is very strong. 10kW. Strong enough for decent propulsion for my boat.
but, I am not sure whether this concept is good for steering.

 

[dvd]

That is a folding boat. The motor transom was design to react the forces from the motor. Are you going to mount the motors on reinforcement? This propulsion seems ill-advised based on your craft.

 

[FluidPowerUser]

20KW to propel a boat like that is asking for trouble.

It's entirely possible to control the orientation of the motors with proportional control, but the power will likely damage or destroy the boat.

 

[LittleInch]

I looked up those boats and they are rather neat, but inherently flexible. The vendor says they flex up to 12% when they hit a wave....

There is no way they can take motor force other than directly in the centre and I don't think they could handle more than about 5 to 7 Hp, so 5kW max.

Steering using differential thrust is possible, but normally very difficult to keep a straight-line or make small adjustments for wind or to make a gentle curve. Great for doing doughnuts in the middle of the lake, but otherwise not much use for anything else.

But fit those to that boat and I don't think the craft would make it to the other side of the lake.

Take a life jacket, some flares and a waterproof radio for when the boat breaks up mid crossing.

We had a fibreglass dinghy about that size and a 2hp yamaha outboard and even that flexed the rear transom. I would say 5hp absolute max in the centre only.


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[rothers]

You will need a matching pair of props 1 left hand 1 right hand. Props will need to turn in opposite directions i.e. Looking from the stern forwards the left hand/port prop should be rotating clockwise, right hand/ starboard prop rotating anti-clockwise when going forwards. Otherwise trying to go forward in a straight line will be interesting (paddle wheel effect).

And as others have said, over 20 HP is way too much.

 

[rb1957]

really ? I'm surprised it is a case of "you Have to do it this way". Airplanes would often have twin engines rotating the same way (for economy) and. sure, they often had issues with the resulting torque and roll moment on the plane. Same planes (P38 comes to mind) had handed propellers, but I've never heard that it Had to be LH CW and RH CCW.

That looks like a very small propeller for 20hp. I wonder about the weight of the battery ?

I'd've thought a rheostat would be able to control both motors? But you can tell it is designed for one motor on the CL. If you insist, I'd mount the two motors onto a board that I'd attach to the central "handpoint".

"Hoffen wir mal, dass alles gut geht !"
General Paulus, Nov 1942, outside Stalingrad after the launch of Operation Uranus.

 

[JStephen]

What do you do if one motor goes out?

 

[rb1957]

send the good one to zero, and drift ? or ...

go around in circles ?? (or maybe linked arcs ??)

"Hoffen wir mal, dass alles gut geht !"
General Paulus, Nov 1942, outside Stalingrad after the launch of Operation Uranus.

 

[LittleInch]

"What do you do if one motor goes out?"

Use the oars!

Maybe also for a bit of steering...

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

 

[TugboatEng]

Yes, you can steer a boat this way. We call it twin screwing in the tugboat world. It can get you home after a steering rudder failure but that is all. Maybe it would be more feasible with electric due to faster thrust reversal.

 

[telecomguy]

I think 'Zero-turn Mower'.

<tg>

http://xdi.me

"If there's something in life you don't like, change it and deal with the consequences." - James Tanton

 

[Strong]

Apparently the OP is on vacation or unavailable to discuss the proposed design versus the pros/cons of the Comments. If both motors have the same propellor blade orientation and rotation direction, then it could be a fun sideways boat ride!

Walt

 

[LittleInch]

Maybe he tried it out at the weekend and the boat sank?

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

 

[mingki]

Hi thank you so much for your answers.
No, I am not dead yet cause I haven't tried a test yet.
So, it seems that the design would be feasible for propulsion and steering if I reinforce the boat structure properly.
Now, I understand.
The propulsion system will enable me to push the boat gradually so I will stop the throttling when I feel something wrong during propulsion.
I am applying this differential mechanism to my boat.

https://www.youtube.com/watch?v=0TmdU9W5eXg&t=17s

And the boat will be equipped with this FPV function.

https://www.youtube.com/watch?v=zGgGbZcR4g4

The boat will be unmanned so there is no risk of me being drowned.
I will give it a shot and share the result here.
Thank you!

 

[LittleInch]

The boat is unmanned?? So what's in it??

This is a folding boat. You won't find it easy to " reinforce".

I don't think this is really feasible Why do you do?

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

 

[mingki]

I see, then could you recommend me some other boat that is feasible for this project?
My plan is to develop some RC boat for rescue activity that human can ride or hang on to.
This is a preparation for upcoming flood disasters in the summer because there are so many unusual heavy rains these days and it doesn't look good.
The reason why I want to develop such RC boat is that there are so many people required to operate one big rescue boat in case of disaster as below picture.

It looks cool but there always has been shortages of such rescue man power especially when it comes to critical moments for rescue activities.
So, my plan is to have a autonomously driven rover attached with a rescue boat be ready for 24/7 at some places and deploy the boat only by one operator and the boat remotely controlled through FPV camera up to 10km or more.

I think the overall cost of this boat building shouldn't be exceeding 10,000USD for single boat so I need a cheap but reliable mini boat.
The boat will have battery pack, control module, and a camera in it. That's it.

 

[dvd]

Maybe it is your intention to install the motor/prop in a shroud or tube, but that spinning prop would cause some real damage to some poor soul being rescued remotely in rough water.

What is wrong with using the extremely flexible inflatables instead of that folding boat?

If you were going into production with some sort of autonomous lifeboat, you might think about using expanded polystyrene shaped like an oversized lifesaving torpedo. It would be a (possibly recyclable) short-lived unit.

 

[mingki]

That's a good point. Yes, there is a great hazard of propeller being a damaging tool.
I have been thinking about this for a while and the only solution for this is putting indications on the boat and also use this drone speaker so that the operator could tell the passengers not to come closer to the back side of the boat when the boat is operating. Or I just put waki taki or something.

Using inflatable boat is fine with me. I was just worried that it might be punctured by some sharp edges but I guess the material is tough enough these days. I will check it.

 

[TugboatEng]

Putting the propellers in nozzles eliminates prop walk which will simplify your steering. It can also make the system more efficient at low speeds.

 

[Stick.]

Operating in floodwaters makes me think that you need to be prepared to hit stuff that's hidden underwater, doubly so if you don't intend to have a human on board. Tug's prop nozzle idea would help keep the props from being damaged, but you still risk damaging the motor itself if you hit something hard enough. That makes me think about jet based propulsion (like a jetski), but maybe there's other issues there too. Have you contacted anyone who actually does these types of rescues to see what works and what doesn't?