fathom

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Cold water

vaughanzachary
Thu, 29 Sep 2016 14:51:42 GMT

How's well will the Fathom drone work in cold to very freezing water? [Sea_ice](//muut.com/u/fathom/s1/:fathom:LLOC:sea_ice.jpg.jpg) For example.

John Boss
Thu, 29 Sep 2016 14:56:21 GMT

Developing the F1 in Michigan, we're no strangers to freezing water. The biggest thing we had to look at was lens fogging, which we counteract with embedded silica gel!

bocaceia
Thu, 29 Sep 2016 14:58:15 GMT

I would have gone with a spit dispenser ;-)

thedigitaldoctor
Thu, 29 Sep 2016 15:00:07 GMT

No impact on battery life? I operate a UAV business in northern Alberta, Canada; we haven't experienced too much loss in sub-freezing air, but I wonder if cold water might be a different story... I look forward to testing!

John Boss
Thu, 29 Sep 2016 15:06:01 GMT

@bocaceia, sounds like something we need to check out haha. @thedigitaldoctor, the cold water will inevitably have a slight effect on battery life, but I don't foresee it greatly effecting mission times. We'll know more about the actual effect when we can run more tests as the winter months approach.

paulruai
Thu, 29 Sep 2016 15:48:24 GMT

silica gel for anti-fogging is a short term method.. over time the operator needs to replace or cook the silica gel to remove the moisture.. would the lense area be accessible for the operator?

John Boss
Thu, 29 Sep 2016 15:52:26 GMT

@paulraui, we embed the silica gel during the last stage of assembly before the "seal up" step, so that internal fog-causing moisture is absorbed. We didn't experience any fogging once the moisture was absorbed - have you experienced issues with this before?

paulruai
Thu, 29 Sep 2016 16:20:25 GMT

yes. in the long run, the silica gel will reach its saturation point.. and will eventually be evaporated when the ROV is in storage.. condensation still continues not unless the interior of the ROV is vacuumed or hermetically sealed.. the ones in the field use optics that are outside the ROV, not in the main housing

paulruai
Thu, 29 Sep 2016 16:26:40 GMT

not the silica gel evaporating, I mean the water moister

John Boss
Thu, 29 Sep 2016 16:32:02 GMT

@paulruai, great point. The reason we haven't had an issue with it up to this point is because the hull of the drone is completely sealed to the environment, not allowing additional moisture to find its way in. The amount of silica gel has been calculated to ensure there's enough to take care of residual moisture inside the hull, without becoming completely saturated. I was under the impression silica gel only released its trapped moisture under very hot conditions? I may be wrong on that. Thoughts?

periwink
Thu, 29 Sep 2016 17:12:14 GMT

I use silica gel to dry marine air at work, it is quite effective. In an enclosed environment it should come to an equilibrium and have no further water to react with. I've dried it in a home oven, however not quantified how effective it is in reuse. I'd suggest putting the silica gel in a oven safe bag or container so it can be removed and baked. Also, the variety I use changes color as it absorbs water so a window or similar might be a good idea. Since you're in Michigan, I'd suggest sealing a system in something like a sauna then submerging it... I can't stress how much water condenses in a tropical marine environment (equatorial, or even the Mississippi or California) from atmospheric temps to water temps.

John Boss
Thu, 29 Sep 2016 17:38:26 GMT

@periwink, thanks for the suggestions! It's funny you bring up intentionally changing the environment temperature to really soak up the moisture - when we were early in the alpha prototyping phase we actually stuck a prototype in the fridge after assembling it in a hot, humid environment. Pretty amazing to see how much water condenses!

periwink
Thu, 29 Sep 2016 17:56:39 GMT

@jboss that's a good way to test! No place like mixing electronics and water to instill paranoia of moisture. The other side of the coin is cold gear opened in a humid environment and the condensation on components. That's on the operator though, it should be brought to room temp before servicing (plus new silica!). Congrats on the Kickstart btw, looking forward to playing with mine!

John Boss
Thu, 29 Sep 2016 17:58:44 GMT

@periwink, thanks! We're so excited to get these units out the door to see what our backers come up with! Personally, I can't wait to start sharing dev. updates as well. A lot coming down the pipeline!