I’ve been testing our upcoming subsea servo product for this application, raising and lowering a fish trap with light on the BlueBoat, as well as a battery powered CTD. It works great, with continuous rotation (winch) mode available!
While there isn’t a launch date for that yet, in the meantime Blue Trails Engineering just updated their lineup of subsea servos….
If you’re trying to stay super cheap, the waterproof hobby servos would work fine on the deck of a BlueBoat, they just can’t be submerged very deep…. it’s also unclear if they can be reprogrammed to support continuous rotation!
Thank you for these links! While the subsea servos seem very capable and ±3.5 full turns isn’t nothing, I would like to move within a range of at least a few meters, meaning I’d have to attach a gearbox of sorts to such a servo. In any case, I’d still have to bring my own wire spool mechanism…
Understood - I hadn’t realized they were limited in rotations fundamentally! There may be low-cost options out there that are IP67 (not rated for submersion, but likely ok for a surface vessel mini winch application.) Let us know if you find one!
Well, there exist continously rotating servos but at that point it would be almost the same as just building the thing from scratch using a DC motor with integrated encoder.
Very cool! You may be able to get around the lack of feedback by running for set time periods, and using a proximity switch to detect when the payload has been fully retracted?
The spool on these looks pretty small, even some kevlar kit-string may only be able to fit 10-20m on it?
I guess you’d be right about the depth but there are a few similar products available (all with pretty limited info, regrettably.
About the feedback: The full retraction could be done with a sensor, yes. But it would also be interesting to be able to tell when the winch hashed its move at a depth you had requested from it. I guess the servo could be hacked, but then it would lose its water ingress protection…