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I've experimented with building a submersible robot and - by far - the most challenging aspect of the build was creating an interface between the motor and the

I've experimented with building a submersible robot and - by far - the most challenging aspect of the build was creating an interface between the motor and the propellor that was waterproof in a reliable way. (applying grease or something hydrophobic on a shaft lasts only so long) By abstracting away that schlep for me, - a schlep, which is usually the least interesting bit about a machine - these guys might be able to create something analogous to Arduino for marine robots. Before Arduino, you needed a complete test bed to get a micro-controller up and running. After Arduino, you usually focus on what you want to do, instead of getting the micro-controller to work. That shift makes creating something extremely accessible, allowing anyone to jump in and try things out. A line of products like these, might actually make robotics far more accessible than any number of kits before it. In other words, this could be the start of something incredible. Edit: I just realised another way of phrasing what they're doing. Imagine how hard payments was before Stripe came along. These people are basically the Stripe for marine robotics, which is really awesome.

ChuckMcM 12y ago
I saw a really novel water tight propeller system where the shaft of the propeller had permanent magnets on it, and inside the boat there were coils that pushed against them. The propeller was in a hermetically sealed shaft. No crossing points at all. Probably not as efficient as other solutions but I am sure it did not leak anywhere.
- todayiamme 12y ago
  That's actually quite impressive and it ties into why I started the project. When I was a teenager I read a paper that talked about the drive used by Captain Nemo in Twenty Thousand Leagues Under the Sea. The magneto-hydrodynamic drive† basically tries to push seawater through a set of coils and, as you've said, it's very, very inefficient and currently impractical. Reading that paper inspired me to look into this and I ended up trying to make a submersible with the limited budget I had. It was very frustrating and I just gave up and ended up trying to make linear actuators for touch sensing instead. †http://en.wikipedia.org/wiki/Magnetohydrodynamic_drive http://en.wikipedia.org/wiki/Magnetohydrodynamic_drive http://www.skewsme.com/mhd.html#axzz3ACp7NENa http://www.skewsme.com/mhd.html#axzz3ACp7NENa
  - netcraft 12y ago
    Wasn't this also the caterpillar drive from "Hunt for Red October"?
    - todayiamme 12y ago
      Yup!
    - apendleton 12y ago
      Only in the movie. In the book it was an impeller.
  - mrfusion 12y ago
    Wow, I never a Magnetohydrodynamic_drive existed! Has there been any attempt to use it in air instead of water? I guess you'd just need a really high voltage?
qwerta 12y ago
> the most challenging aspect of the build was creating an interface between the motor and the propellor that was waterproof in a reliable way. There does not have to be interface. Put stator inside and rotor outside, aquarium pumps works on similar principle.
- deleted 12y ago
  [deleted]
- HeyLaughingBoy 12y ago
  The losses across that gap are expensive, though. Aquarium impellers are moving water at very low pressures. It works if the isolation layer is very thin. However, that prevents you from going deep because of the pressure differential. Now, I wonder if you filled the sub with something inert and kept the layer thin, then the pressure differential would be a lot less and the layer a lot less likely to rip open. Might work.
TeMPOraL 12y ago
> By abstracting away that schlep for me... > I just realised another way of phrasing what they're doing. Imagine how hard payments was before Stripe came along. These people are basically the Stripe for marine robotics Hey, didn't you get the "schlep" and "Stripe" part from [0]? ;). [0] - http://paulgraham.com/schlep.html http://paulgraham.com/schlep.html
jotm 12y ago
Excuse my ignorance, but can't you use the kind of seals that are used at the end of engine camshafts and crankshafts?

ChuckMcM 12y ago

I saw a really novel water tight propeller system where the shaft of the propeller had permanent magnets on it, and inside the boat there were coils that pushed against them. The propeller was in a hermetically sealed shaft. No crossing points at all. Probably not as efficient as other solutions but I am sure it did not leak anywhere.

todayiamme 12y ago
That's actually quite impressive and it ties into why I started the project. When I was a teenager I read a paper that talked about the drive used by Captain Nemo in Twenty Thousand Leagues Under the Sea. The magneto-hydrodynamic drive† basically tries to push seawater through a set of coils and, as you've said, it's very, very inefficient and currently impractical. Reading that paper inspired me to look into this and I ended up trying to make a submersible with the limited budget I had. It was very frustrating and I just gave up and ended up trying to make linear actuators for touch sensing instead. †http://en.wikipedia.org/wiki/Magnetohydrodynamic_drive http://en.wikipedia.org/wiki/Magnetohydrodynamic_drive http://www.skewsme.com/mhd.html#axzz3ACp7NENa http://www.skewsme.com/mhd.html#axzz3ACp7NENa
- netcraft 12y ago
  Wasn't this also the caterpillar drive from "Hunt for Red October"?
  - todayiamme 12y ago
    Yup!
  - apendleton 12y ago
    Only in the movie. In the book it was an impeller.
- mrfusion 12y ago
  Wow, I never a Magnetohydrodynamic_drive existed! Has there been any attempt to use it in air instead of water? I guess you'd just need a really high voltage?

qwerta 12y ago

> the most challenging aspect of the build was creating an interface between the motor and the propellor that was waterproof in a reliable way. There does not have to be interface. Put stator inside and rotor outside, aquarium pumps works on similar principle.

deleted 12y ago
[deleted]
HeyLaughingBoy 12y ago
The losses across that gap are expensive, though. Aquarium impellers are moving water at very low pressures. It works if the isolation layer is very thin. However, that prevents you from going deep because of the pressure differential. Now, I wonder if you filled the sub with something inert and kept the layer thin, then the pressure differential would be a lot less and the layer a lot less likely to rip open. Might work.

TeMPOraL 12y ago

> By abstracting away that schlep for me... > I just realised another way of phrasing what they're doing. Imagine how hard payments was before Stripe came along. These people are basically the Stripe for marine robotics Hey, didn't you get the "schlep" and "Stripe" part from [0]? ;). [0] - http://paulgraham.com/schlep.html http://paulgraham.com/schlep.html

jotm 12y ago

Excuse my ignorance, but can't you use the kind of seals that are used at the end of engine camshafts and crankshafts?