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Trouble with boat thruster build

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Redaustin88
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  • Thanks in advance for even looking.  I’m building a stern thruster for my fishing boat using an old 12volt brushed trolling motor that pulls 40 amp peak.  That would use an arduino, 10k pot to give left right inputs an on off switch for the gyro to keep it pointed in a given direction and a pwm motor control.  I have a terribly crude drawing that I know is incorrect that uses servos to control the pwm. But don’t know how to attach it.    I would like to believe it could and would be much simpler.  Also the on off switch is to turn off the gyro control when not needed. One of my biggest hang ups in my mind is the pwm.  And as you can tell I’m not very familiar with the drone or bot.  Just used to fly rc and like to build. 
This topic was modified 8 months ago by Redaustin88

   
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Will
 Will
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@redaustin88

Can we have a peek at the drawing, it's hard to help if we don't know what we're dealing with. There are a lot of mysteries here:

- why would you think that you'd need to use servos to adjust PWM

- why would you need the precision of a gyro

- how will the gyro be affected by rocking of the boat

- is this just an intellectual challenge or do you really intend to use an Arduino and a potentiometer to control your fishing boat ?

- how will you set direction

 

But it sounds like an interesting challenge 🙂

 

Experience is what you get when you don't get what you want.


   
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Ron
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@will @redaustin88 Another interesting challenge related to this is to build a sonar unit and have the motor follow a depth contour. Or follow a submerged old river bed. My old Minn Kota trolling motor used to do all that.

"Don't tell people how to do things. Tell them what to do and let them surprise you with their results.” - G.S. Patton, Gen. USA
"Never wrestle with a pig....the pig loves it and you end up covered in mud..." anon


   
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Redaustin88
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@will

image

 I know the drawing doesn’t show what my brain is thinking. But it’s a start.  
As per your questions it’s not about precision I’m after.  My trolling motor on the bow already has go’s spot lock and will follow contours like Ron mentioned. But that motor controls where the bow is so if I’m spot locked on a location the main trolling motor holds its self in that spot however current or wind will spin the boat and point upstream or into the wind around. I have 8 14 ft long poles sticking out the front of my boat and when there is a bank or tree beside you and the tail swings in the wind it can and will break poles as they are spun into said objects.   I want to control the tail of the boat and prevent that with the head hold gyro.  Like was on my rc plane.  As how I plan to control it. I was going to use a pot to give input to the arduino that would give signal to servo through the gyro like on rc while the servos control the pwm.  Reason the pwm is being controlled by servo is because I clearly don’t know exactly what I’m doing. And only pwm I can find to handle the amp draw is like these.

image

 


   
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Will
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@redaustin88 

Ok, thanks. That diagram and the associated description clearly indicate to me that I'm not capable of helping you (my experience with boats has been predominately on cruise ships :).

With 14 rods out, it seems that you'd be better just tossing a stick of dynamite into the water and netting whatever floats up. It'd save on bait money too:)

One possible thought would be if you're fishing on a river or a small lake where there's always something visible on the horizon, could you use a camera to check for motion and use that to correct your steering point. You could then keep the boat moving in a straight line. This wouldn't work in very bad weather, at night or in heavy fog but I assume you wouldn't be fishing in extremely bad conditions.

Sounds like @zander has some experience in this area.

Experience is what you get when you don't get what you want.


   
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Redaustin88
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@will thanks for looking 


   
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Ron
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@redaustin88 Just a thought, have a look at boat autopilot mechanisms, maybe especially sailing boat setups. Another thought is using a motor drive like a modern tugboat uses, they are designed to spin on a dime. I believe they use shrouded propellers to give them quicker response. Also a thruster on each side of the rear and a differential pump so that movement one way causes more thrust on that side.

"Don't tell people how to do things. Tell them what to do and let them surprise you with their results.” - G.S. Patton, Gen. USA
"Never wrestle with a pig....the pig loves it and you end up covered in mud..." anon


   
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Redaustin88
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@zander thanks for your assistance.  I’m only trying to move  or prevent the movement by an outside force of a 17 foot aluminum boat. And believe using an old trolling motor would be easiest.  It’s what I’ve used in the past but had to go to back of boat and change speed/ power and direction physically by hand or someone fishing in the rear got to keep  control of the stern.  What I believe I’m looking for is a sketch like this… sketch 2 project 2 with the addition of a gyroscope function when called for. https://techexplorations.com/guides/arduino/motors/dc-motor-speed-direction-lm298n-arduino-project2/   which would clean up the build and eliminate the servos in my drawing.   just don’t know enough to know what speed control to use to handle the 40 amp load.  
thanks again 


   
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Ron
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@redaustin88 The 40 amps doesn't go thru the arduino, the arduino controls some sort of solid state device that manages the 40amps. I am too new to solid state devices to tell you but if @will is still reading he will likely know. To me it sounds like a solid state pot that can handle up to 40 amps with ma inputs. The directionality can be controlled by servos and then you just have to figure out how to control the 'control' servo if that makes sense. If you want to control it manually, then you can use a pot, sort of a remote tiller or maybe you can automate it but that is probably not as accurate as you want.

"Don't tell people how to do things. Tell them what to do and let them surprise you with their results.” - G.S. Patton, Gen. USA
"Never wrestle with a pig....the pig loves it and you end up covered in mud..." anon


   
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Will
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@zander 

Assuming that the motor always operates in "forward" mode and doesn't have to reverse, then you could pick up an SSR in Amazon.

But I would expect that you'd need variable speed to counteract wind and possibly tide, so I suspect that some sort of PWM based power delivery system would be required.

Also, steering via servos could be difficult because the servo arm would not behave nicely with a standard outboard motor lever arm. You may need something more like a worm gear. But, bear in mind that I'm not a boating enthusiast so I don't know much about what's available for motors.

Experience is what you get when you don't get what you want.


   
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Ron
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@will Ah, yes, the comment re servo vs worm gear would appear to be spot on however maybe the following will provide more information 

https://www.lifeofsailing.com/post/best-sailboat-autopilots

NOTE: I searched google for

sail boat auto pilot

"Don't tell people how to do things. Tell them what to do and let them surprise you with their results.” - G.S. Patton, Gen. USA
"Never wrestle with a pig....the pig loves it and you end up covered in mud..." anon


   
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Will
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@zander 

I didn't read it or watch any of the videos because I'm not competent to understand them. but I don't think that sailboat steering systems would be equivalent to an outboard motor.

it seems to me that the sailboat's forward force is generated at the mast(s) and the steering just provides a drag force which causes an imbalance and turns the boat towards the side of the rudder with the most "push".

However, an outboard motor forward force acts directly behind the stern of the boat and pushes it directly to the side with no turning moment as in the sailboat.

I would think that it would be easier to de-clutch the gyro, manually turn the boat into the desired direction and then re-clutch the gyro to maintain the current heading.

Experience is what you get when you don't get what you want.


   
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Ron
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@will Power boats also use auto pilots.

"Don't tell people how to do things. Tell them what to do and let them surprise you with their results.” - G.S. Patton, Gen. USA
"Never wrestle with a pig....the pig loves it and you end up covered in mud..." anon


   
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Will
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@zander 

I didn't mean to imply that they don't.

I'm just saying that, to me, the physics of steering a sailboat is different from a boat with an outboard motor. This is because I think that the sailboat turns around the mast where the wind is applying the motive force and the boat turns around a point outside of the back of the boat (namely the outboard propeller).

You can move the tiller on a sailboat that's not moving because there's no wind and nothing happens. if you turn the outboard motor and hit the gas even when the boat isn't moving it turns immediately.

I see the outboard as being a superior means of transportation over short distances and the sailboat as being a superior means of transportation over long distances.

Experience is what you get when you don't get what you want.


   
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robotBuilder
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@redaustin88 

Reason the pwm is being controlled by servo is because I clearly don’t know exactly what I’m doing.

The pwm is just electronics to turn the motor fully on/off many times per second. The amount of on time to off time controls the speed while delivering full power when on.  Can it be fully on/off? 

I am not sure where the gyro comes into the equation.

The motor controller in the image you attached looked fine to me.

 

motorThruster

 


   
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