How do i make a watertight rotary switch that goes in a 6" PVC tube

[Seville]

I am trying to make a scooter out of a 12v trolling motor. dc to dc step down converter and green works 60v lawn mower battery. The trolling motor has a switch module that has 5 speeds forward and 2 that are reverse. The speeds are activated by a rotary dial.

I would like to put the housing inside the round 6" pvc pipe but I cannot figure out how I can seal it from water getting in, especially since the pipe is convex. Ideally I would want to have the switch outside the pipe and have it on some sort of handle so I could use it like a motorcycle throttle. But doing that I would need to get about 5 wires outside the housing and waterproof the switch somehow. Any ideas how to make this happen?

 

[OTF]

Neat project. Hope the shaft seal on the trolling motor can handle the pressure. But I bet it'll do okay except on very deep dives.

For the switch - a shaft seal with a small o-ring. Lots of resources online and in textbooks on how to design that.

A magentic switch of some sort is also an option but maybe not ideal for a scooter.

Do you have machining capability? Mill or lathe? If so the o-ring thing will be easy.

 

[Seville]

I am not sure if it will hold up at depth either but it’s a fun project for me to tinker with! I dont have access to milling equipment. I thought the shaft would not work because it has a flat portion especially when butted up against the inside of a pipe. Any kind of premade rotator switches?

 

[emoreira]

I guees you should try to install that switch inside the DPV and link it to an external SS shaft that transvers the hull with o-rings. Just like the actuators of the Ikelite UW camera Housings. The SS actuator should have at least 2 o-rings to seal the exterior.

 

[OTF]

Some of the RC submarine websites offer premade shaft seal parts

 

[MaxTorque]

Much easier to just replace that switch with some relays, and drive those relays via some hall effect switches, and use an EXTERNAL ring that has a magnet in to trigger those sensors!

 

[Seville]

do you by chance have any photos of what the hall effect switches look like and an external ring and where to get them?

Thanks

 

[emoreira]

Much easier to just replace that switch with some relays, and drive those relays via some hall effect switches, and use an EXTERNAL ring that has a magnet in to trigger those sensors!

In fact you should be refering to Reed Switches.
Switches | Magnetic, Reed Switches | DigiKey

Magnets do corrode, so the magnets that should be used must be enclosed to avoid corrosion.

 

[OTF]

I'm not saying not to do it, but be careful about trusting reed switches on a DPV. They can stick or be unreliable sometimes. You wouldn't want the scooter to stick on full speed ahead unintentionally.

 

[ThatDogDontHunt]

If you really want to play around with oring seals it may make sense to brush up a bit by looking at the contents of the Parker Hannifin Handbook. Way too much detail, but they do provide some good info on both static and dynamic oring sealing.