Chum444, looking at your harbor👍 it looks like you have quite a lot of experience with Korts and z-drives.
Lew
Florida ⛱️, USA ❤️

One final comment. Here’s what’s possible with a single steerable Kort nozzle. I hope your dad rebuilding continues apace Lew. Clearwater incurred a lot of damage.
And, good luck with this project. Keep us posted with results.👍

Chum444, et al. ..

Like many projects and ideas this will require experimenting. Still don't have my shop back up to get into the "nitty gritty."

I am now 81 and never had an experience in my life like we have gone through. Imagine getting up (no sleep) and walking through your home splashing in water, wind still howling, raining hard, and outside was water everywhere. No grass, no sidewalk, no street, just water. No power, trees down. Then slipping off a step and falling in 5 inches of floodwater. Wife had to help me up. Rescue responded when the storm eased some. Went to the ER - fortunately nothing broken, just pain.

Strangely enough if the water was only 1 inch lower most of our flooring would have been safe. Others had it much worse. Six houses down from me a home completely burned. Fire rescue could not respond during the hurricane.

I did not mean to get off topic here, but I did want to thank all of you for your concern and best wishes. This means a lot to me 😊 and is still helps me stay level headed and looking forward on getting my fingers working on models and being done with repairs and moving/restoring everything.
Sincerely,
Lew
Clearwater (north of St. Petersburg)
Florida ⛱️, USA ❤️

Morning LewZ. Seems like you & Simplesailor have this under control. I certainly don’t have any value to add to an electronic discussion. For example, I would buy the servo toradog recommended & program it for 360° operation instead of hacking a standard servo.😂😂 Speaking of servos, I think the Futaba # you mentioned should be fine for torque.
On another subject I’m glad your hurricane damage repairs seem to be coming to an end. Very hard & I’m guessing rather depressing work. Are you located on the St. Pete or Tampa side of the bay? I have some familiarity with the Tampa side.

Hi LewZ.

Nice explanation of how a servo uses proportional feed back to make the output shaft stop at a given point. I am sure everyone already knows the following. The problem with using a potentiometer on the output shaft (as per most servos) is the travel is limited to the travel of the potentiometer (about 270°) But as per sail winch servos you can put the potentiometer on another geared shaft driven by the output shaft. If you use a 2-1 ration gear the output shaft would turn about 540°. (about 1.4 rotations) It could not continue past that point. I am not sure how the commercial 360° servos work. I assume if using a potentiometer they have to stop at 360° and then return due to the limitation of the potentiometer. However some years back I made a made a servo that would work like a stepper motor. I used a basic servo with the end stops removed, then replaced the potentiometer with an optical encoder mounted on the output shaft. This was all driven with an Arduino Nano and some code which I pulled from the inter-web of things and modified to suit my needs. This was for a Sail Winch which I had designed (See pictures of original prototype) You have now intrigued me with the TX controls and how to mechanically and electronically emulate the control without having to destroy a perfectly good TX. Maybe something for my project list. 😂

SERVO - how it operates (for simple people like me)...

Years ago I modified two old servos to into inside my 1/35 scale LCM (see photo 1). By removing the limits and the gears between the motor and the potentiometer I was able to use the output shaft and connect to the prop shaft. This setup gave me forward, stop, and reverse and a variable speed to each drive (two shafts).

You can also use the above setup for a rotating radar (on many other things).

How does this help me with rotating the Schottles's Kort? Well the video at the bottom explained that to me. The transmitter sends signals to the receiver and that eventually goes to the servo. Inside the servo, the circuitry receives that input signal and compares it to a signal generated inside the servo which is varied by the potentiometer.

Normally this would eventually "tell" the motor to move to a new position (via the gearing between the motor and the potentiometer) when the transmitter's joystick is moved.

No gears, no end stops/limits (like my LCM)... With all the gears and end stops removed the output shaft runs continuously. As an added feature the servo's circuitry will also vary (slows down) the voltage as the two signals match. So with the potentiometer zeroed with the joystick centered, as you gradually move away from the zero point the more voltage is applied to the motor and the faster it will turn. Cool!

Back to the Schottles... By removing only the end/limit stops, the motor should run to match the input signal. I still need to figure out how to modify the transmitter. I see that there are continuous turn (360 degree) potentiometers out there. Need to find out how that works in relation to the pulse generated signal required to make the servo match.

Update on the servos I have for the Graupner 2235 Schottles: These are Futaba S3305:

Metal gears with two ball bearings
Speed: 0.25 sec/60° @ 4.8V 0.20 sec/60° @ 6V
Torque: 124 oz-in (8.9 kg-cm) at 6V 99 oz-in (7.1 kg-cm) at 4.8V

Lew
Florida 😎, USA 😀

I found this video (link below) that gave me a lot of information on how a servo works while being quite entertaining:

Gents,
Take a look at GoBilda servos. They can rotate 300 degrees. They are also re-programmable to to provide 360 degree proportional rotation.

https://www.gobilda.com/servos

Thanks Lew. The 2235 looks to be a much better unit than my 1761. Do you plan to go to a 360° servo & then change the gimbals on you tx?
If it helps, I also found that you need high torque servos since the Schottles create high torsional loads as they proceed through 360°. Then it was suggested to me not to depend on the esc’s BEC but provide a separate battery for power to the rx. Both turned out to be good advice.
After several builds to decide the best maneuverability & low maintenance propulsion system (single or dual Korts, steerable or fixed) instead of Schottles I found a single steerable Kort nozzle was totally acceptable. Does everything but crab walk while minimizing the required running gear.

Chum444, no apologies needed! I respect all input. When posting questions on this site, the object is to avoid duplicating mistakes that unfortunately might have made, and I am no exception.
Fortunately, the Graupner 2235 schottle does allow for continuous rotation of the Kort nozzle (the 240 degreem limit on my 2235 was caused by the servo limit). Just have to work out the kinks circuit wise.
Thanks for your input!
Lew
Florida ⛱️, USA ♥️

Morning Lew. I think you have run into the issues I uncovered during construction of FERRIBY. Having seen videos of real ASD tugs I too was excited about 360° rotation for maneuverability purposes. The sector gear used for steering on the Graupner 1761 Schottels simply won’t accommodate 360° rotation of the drive even if the servo has that degree of freedom. The sector gear would simply be overthrown from the mating “rudder” gear. That is why Umi replaced the sector gear with a full 80 tooth gear. Even then she said only 270° was achieved. I don’t know why other than perhaps the servo’s limit's
Apologies. I should have said when I posted this that the following comments are my humble opinion.🤔
Thus I fell into the “why”, other than for engineering satisfaction, trap. Reversing direction of the tug can be accomplished the usual way & unless one participates in the big boy towing competitions in the Pacific Northwest crab walking the tug is not a necessity.
This all led me down the path of seeking the best compromise to achieve reliability while maximizing maneuverability. Other folks, much more experienced with tugs than I, might have different thoughts.