Winter dives in freezing conditions?

trident

#1

Hi,

I’m a Trident kickstarter supporter, and I’m hoping to get my new Trident in November. However, that’s winter time here in Norway, so the conditions can be freezing. Can I hack a hole in the ice and dive with the Trident in these conditions? I think my main concern would be when I lift the ROV up out of the cold (but warmer than freezing) water into freezing air. Water in any small cracks or crevices will freeze and expand, with enough force to crack rocks.

So my question is, should I keep the dives to “warmer” days, eg warmer than freezing? Or can I venture out into the freezing cold without worries?


#2

Hi ketil1!

Trident is certainly being designed for under-ice diving. In fact, the concept for Trident initially came together durring an expedition in Antarctica where we were deploying a (much more expensive) ROV under the sea ice in the Ross Sea. Tridents dimension should allow it to fit down a standard 10" (250mm) Jiffy Ice Drill hole.

All that being said, I should be careful to mention that we haven’t yet done empirical testing of Trident in extreme cold conditions. We’ll learn a lot more about how freezing conditions (and other environments) affect the vehicle after we’ve done more field testing, and we’ll try to publish best practices guidelines once we have that info.

Great question- it will be fun to see Trident being used in such interesting places!


#3

Thanks for the response! I look forward to getting more info on this, but I’ll probably try to keep my dives to days that aren’t super cold before we know more.

Winter water is much clearer (in many places, anyway), so from that perspective the cold should make for superior exploration conditions! For example, a small bay I often visit during summers is mostly 70-100m deep, and has a 40m deep plateau somewhere out there. Locals tell me that they can see the 40m deep plateau from boats in the winter. In the summer, it’s all just darkness when looking from the surface. :slight_smile:


#4

Is it possible to have a waterproof box on site when you retrieve te ROV. ROV into box ; pour buckets of water from ice-hole into box, with some salt (or other freezing supressant) until ROV covered in water ; lid onto box ; pack up and leave site. At base / workshop you can unpack the kit in (relative) warmth.
By the time you’ve got the lid on the box, it will take much longer for the whole box to freeze. Even just keeping the wind off it will improve matters a lot.
Plan B - if you haven’t got time / weight for plan A might be to have a large waterproof bag to put the ROV into, then add an anti-freeze to the bag which isn’t an environmental poison (alcohol from camping stove, for e.g.). Pack up and get to somewhere (relatively) warm. But you’d have to check the compatibility of the anti-freeze with o-rings, lube, etc.
I was talking to a man from Poseidon (diving regulator manufacturer) who recommended “winterising” their demand valves by filling with Malt Scots Whiskey - doesn’t freeze (well, to ~ -60C) and doesn’t damage their o-rings or lube. So stove alcohol is probably a good (cheap) start point.


#6

I dive the great lakes with some frequency. Most of the precautions we take have to do with valves freezing which won’t matter here. I think if you have an issue it will be topside

  • Where the tether meets the water will be a ball of ice, will that make retrieval harder or cause a mechanical failure?
  • If a touchscreen is two wire it has a distortion below certain temperatures. This is an example of needing to use the right equipment topside to control the drone
  • If the top blade (which controls pitch) is idle will you get ice build up?

I am going to jump in on the early order as well.

I am not sure how you plan to test in cold water but for what it is worth I live across the street from a harbor that the Chicago Fire Department SCUBA rescue team does it’s winter dives.

I’ll be happy to walk to the end of the pier and toss the unit in the water to see what happens.


#7

Can we get condensation problems inside the hull of the Trident at low temperatures or high rapid temperature differences. This may however eventually be devastating on electronics in Trident?


#8

We are doing everything we can to mitigate this problem in Trident.


#9

If there is enough humidity in the electronics box to freeze (or dew) under environmental conditions, then you’ve probably got a corrosion problem with your electronics already.
Silica gel - dried, in a cloth or paper bag and stored in an airtight bag until put into the electronics box - is probably your safe starting point.
A lot of desiccants have cobalt chloride as a humidity indicator - desiccant working is blue, desiccant exhausted is pink - which will activate at some particular relative humidity. Make sure to change the desiccant when it ceases to be effective - which means including it in your pre-launch checklists, dry desiccant in the packing list … etc.


#10

I’ll be testing my Trident for the first time tomorrow in a nearby lake. Weather fircast is -2C° and light snow. We’ll see! :wink:


#11

@c.causetout I’m looking forward to seeing how your dive goes! We’ve seen videos from a few Trident dives in very cold conditions and even under ice and they seem to have gone well. There’s something awesome about looking at things in environments and conditions that humans would rarely see! The only thing you should be aware of is that the cold often decreases battery life, so expect your dive to be shorter than it would be in warmer water- I’d expect more than an hour of dive time at full charge but less than three. We did some dives in the snow at Lake Tahoe a while back and had a great time. Here are some photos I dug up. Enjoy your deployment! ~Eric



#12

Hi Éric

Water was 5°C, air temperature was -1°C

Battery life was actually pretty good! I didn’t use it all up but it still showed about 3hrs+ after about 35 min of testing (with lights on).

A few suggestions for the OpenROV Cockpit app:

  • Include a 2nd compass heading based - on the controller/ phone’s orientation (if available)

  • have the option to record video with controler view data (heading, depth, time, temp)

  • include on-screen warning message when wifi signal to topside deteriorates below a critical value. (I was tinkering with a towable topside float, very rough “beta” design though :wink:)

Will keep you posted about the next experiences!

Christian


#13

There is a you tube video of a dive under ice in the North West Territories Canada woth watching. FYI