This holographic /prismatic tape works wonders. Cheap and easy - just put some around the deck like a police line. Read the reviews. It irritates the birds because they cannot see/notice predators with the constant flicker.
https://www.amazon.com/Premium-Qual...keywords=Duck+Repellent&qid=1670470562&sr=8-7

f you'd rather do an electronics project, ignore this post.

 

So despite the creative suggestions on my form factor-

Could you draw a picture of what your form factor is meant to be, with dimensions?

I am not sure if you are interpreting the "20kg" as load bearing rather than than the torque that it is. I also thing you are probably better off with a radar sensor than an ultrasonic one.

 

I was not even considering laser pointers, which are not so powerful. I am thinking about one of those many faceted fake jewel lenses like are used in some light shoes, that rotate with a small motor . But if the ducks sleep with their heads tucked in like some birds do, that would not work.
For them an ultrasonic "beeper" like is used to keep birds away from loading docks may be the best choice.
For the timer circuit to trigger any sort of periodic disruption, a two-stage 556 IC dual timer will be the way to go. The first timer has the delay between actions, the second timer produces the initiating trigger pulse. Both time intervals are within the common time delay specifications, and well within the accuracy capability. Use an MPSA13 npn darlington transistor to drive the control relay, because it will not load the timer as much.
I still suggest a spring-driven sweep with the motor doing the reset, because that way if the sweep gets jammed by an obstacle the motor will not be stalled and overheat. And the spring will provide a persistent push to motivate slow ducks to hurry up and move. And the best part is it would not require a motor reversing system.

 

Could you draw a picture of what your form factor is meant to be, with dimensions?

I am not sure if you are interpreting the "20kg" as load bearing rather than than the torque that it is. I also thing you are probably better off with a radar sensor than an ultrasonic one.

My vision is 4 or 6 inch PVC pipe 10" or less high-
190degree notch 3 inches down for sweep arm.
sensors placed just above this opening.
then figuring out how to stuff everything inside.
component list is attached to the post not in assembly order.
my goal is to identify components then start testing.

 

This holographic /prismatic tape works wonders. Cheap and easy - just put some around the deck like a police line. Read the reviews. It irritates the birds because they cannot see/notice predators with the constant flicker.
https://www.amazon.com/Premium-Qual...keywords=Duck+Repellent&qid=1670470562&sr=8-7

f you'd rather do an electronics project, ignore this post.

Thanks for this, I am aware of these types of products- they do have a place here and there. But- it is winter now, the boat is wrapped up and I need a project so I am going to try to muddle through this knowing that I am starting at 0.

 

I described the time control, the actual circuit is published in many places.
For a deck 14 feet long, using a 7 foot pole, you will need a gearmotor with strong bearings, or at least some arrangement to resist the side-load force.Also, unless there is a crank mechanism, you will need a reversing scheme. A lot of those have been shown in this forum.
The spring drive and motor reset concept will allow you to have the motor only rotate in one direction, so that is worth considering.

 

You can also use an electric drill/drive as the motor. At low speeds, they would (should) be fine. The benefit of an electric drill (a reasonablly good electric drill/driver) is that it would come with a clutch that will just let the rollers click over the cam when it hits an immovable object. Or, if you use a stepper motor, the stepper will just cog last the pole with no gear grinding.

 

For 14 ft by 3 ft, I would use 2 sweepers with 3.5 ft rods.

 

On my grandfathers sloop, the "John B", there was a canvas cover that was pulled over the area where seagulls would tend to gather to eat the corn that the cook routinely spilled. There were not many ducks around the Nassau area at the time.
So, while "AN ELECTRIC DUCK DETERRENT DEVICE " would indeed be really cool, a plain canvas cover that sloped at least 20 degrees would keep all of the ducks off, as well as keeping stray seagulls off.

 

A windshield washer pump runs on 12V and costs about $10 for a generic replacement, or less if there's a scrap car to borrow it from. Or maybe you have a spare bilge pump lying around. First step would be to take a squirt gun to a place where ducks hang out and see if it annoys them or not.
With a mechanical arm, there's a slight risk of a duck getting caught up in it, and then someone posts a video and you become famous.

 

Or you could be altruistic, and hire a couple of homeless people to sleep on the platform every night.

 

Or you could be altruistic, and hire a couple of homeless people to sleep on the platform every night.

Homeless folks sleeping on a platform at the rear of the boat might fall in and drown and that would be a rather bad show indeed. So I suggest it is not a good choice.