Skid Steering / Differential Thrust on boat

Good day all! After several years and rebuilds, our 4-H club successfully built and ran a 6 foot kayak for lake mapping.

We had to have a platform that tracked incredibly straight, and wouldn’t tend to be blown around by wind or waves. This hull shaped has worked out amazingly, as it runs like a arrow through the wind. In order to get it to turn, we had to build a rather large rudder and hook it to a large waterproof servo.

While it turns great, and we were able to tune it fairly well to hold a course over a long distance, the rudder has proven to be the weak link. The linkage hardware and servo control horns just can’t stand up to heavy use, and being moved around for presentations. The slightest bump will cause it to break, and I have had to go swimming more than once to get the project back.

Since it’s powered by a single T200 BlueRobotics thruster, and has a fwd / rev ESC, I have been thinking of doing a skid steer setup, and doing away with the rudder all together.

My only concern is if the skid steer is forward only, or if it will run one motor in reverse. It takes A LOT of effort to get the hull turning, and the thrusters are going to be fairly close together.

Does anyone have any experience with this, or can recommend heavy duty, reliable hardware for steering control??

Skid steering will run one motor in reverse if it needs to for turning. Maybe two thrusters midship would provide more in the way of spacing for skid steering to work better.

The video by @rmackay9 here and the thread could be of some help, although your project certainly has more mass to control than a boogie board: Mapping a lake with ArduPilot.

Also, it is great to see such an ambitious 4H project.

Can i add a question. If 2 new separate esc"s added. Do i need to program my esc’s through rc transmitter first then connect to pix hawk thru pwm to rc and ppm to pix hawk?

Thanks for the replies everyone. This is the third generation of our boat. The first two were air boats that were a nightmare to control due to their size. We also wanted this project to be able to be reproducible fairly easy. I would love to have a set of pontoons made to exactly what we need, but it’s hard to argue with spending $88 and having something you know won’t sink!

I did the math, and to add another T200 thruster in, will cost about another $250. While perusing the forums here, I came across ServoCity.Com. I found some heavy duty servo gearing components that would work fairly well. On another site, I found a person that was using a thruster mounted to a rotating shaft for steering, with no rudder at all.

$50 in parts later, I think I have a solution to my problem that will work. I’m going to start working on it this weekend assuming the parts come in on time. If it still doesn’t work as I want, then I will be going with another thruster and moving the whole works to the middle of the vessel.

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