Update - Hydrophilic Sky Unit



Hi there

I haven’t been on for a while as I have had many things going on that have kept me busy.

I just wanted to post a quick update on my hydrophilic coated Sky unit. We’ve just had a week of stormy weather - persistent heavy rain with severe gales, heavy showers with convective gusts of wind etc.
The Sky unit has been working an absolute treat! The wind direction has been consistent and correct even after sideways rain, meaning that the hydrophilic coating is working exceptionally well.

The problem before was that the wind directions would be changing to almost every compass point after rain & wind, due to droplets hanging and wobbling beneath the sensors. As it stands now, it seems to have been eliminated. :slight_smile:

As I said, just quick update but i’ll keep monitoring it.


Seems like a good idea, can you tell me more?

What brand did you find useful?

My batteries are dead in Sky and I need to get up on the roof and replace batteries and might as well try that too?


I wonder if this is similar to the one being tested officially by WF? I’d be curious too to know which brand & product. I’m also curious if this resulted in accurate wind speeds under the same adverse conditions.

One other thought, this is ‘hydrophilic’ and not ‘hydrophobic’?


Thanks for the update, @moeythomas!

Yes, this is one of the six formulas (two hydrophillic, two hydrophobic and two super-hydrophobic) being tested with a group of willing testers including @moeythomas

Good question! Our initial small-scale field test has been somewhat “blind” (we didn’t tell the testers which coating they were getting) but I guess I can tell you now that the formula @moeythomas has is the clear winner, and it’s one of the “super-hydrophobic” variety. More widespread testing is required, but these early results are extremely promising. Stay tuned…


How, if at all, will this coating help reduce the snow build up on the Sky?


We’re focused on rain right now, but that should be an added benefit. The coating is also designed to reduce ice and snow build-up.


Is this a coating similar to “Never wet” ?


Similar, but better :slight_smile:


How soon will we be informed of a product we can purchase and apply to our Sky?


Interesting @dsj
Will follow this topic closely.
The last couple of weeks we had much strong winds with rain. But I never got any false and/or strange wind readings.
Sky is still going strong.


What is on the unit I have?


i’m still don’t understand how or why rain droplets effect the wind measurements. Wind speed is determined by subtracting the time a pulse travels from transducer A to B from the time it takes to travel from B to A. If there is a droplet lying on the plate, the time will be shorter from A to B but also it will be shorter from B to A. Due to the subtraction, it doesn’t matter, and windspeed should still be the same.

Apparently it does depend on the droplet being present, but I just don’t understand.
Or is it because the droplet is moving in the wind?
@dsj do you have any thoughts on this?


I suspect that because the droplet is not smooth and variable that the times won’t automatically cancel out. Furthermore, the reflection might be rejected due to unreasonable time. Here is what a 6 hour polar direction map looked like on one if my units. It is stock.

Here is what the same 6 hours looked like on my second unit I coated with R1 Coatings.

When I saw this discrepancy I took a look at what the R1 Coatings one looked like because it was showing wind 180° out from reality.

It is entirely possible that those droplets scatter the sound to the point that it isn’t picked up at all or that its time is too far off so it is rejected. After wiping only the bottom surface the wind direction readings returned to normal.

Here is a look at my stock unit, at another time, when it was giving strange readings:

If you zoom in you can see water hanging off the nearest sensor. This also had the effect of changing the direction reading about 180°. I took a video of this one, too: https://1drv.ms/v/s!AmVyCndqX9Gsop4rhXDiymlq7TrAAw
Sorry for the poor stability. The pole was wiggling and I have to stand on top of my brick chimney and hold my phone up at nearly arms length to video it.


I have noticed that my unit gets covered in dihydrogen monoxide.


Bonjour, quelle application utilisez vous pour mesurer le vent ?



So David, are you saying in this case even though you had your ‘R1’ coating on one unit, it performed worse (wind direction 180 degrees out of phase from the actual direction) than the unit that had no coating and was giving the correct direction?


I’ve seen same 180 behavior between my two as well. They are remote so wasn’t able to eyeball them. Looked like someone had twisted a mount 180 degs.


If a measurement gets rejected, that would be fine. Better a rejected one, then a wrong one.

your video shows that the droplets are moving a lot. That might throw off the measurement as I assume measuring measuring the pulse from transducer A to B is done not exactly at the same time as the measurement from B to A. Making the plastic even more hydrophobic by coating it, might be good as droplets are more easily blown of the plate, but it might also be worse because it makes droplets move more easily. Only experiment can tell.

A long time ago I posted the suggestion to make the plates more cone shaped so the water cannot enter or when it does enter it will simply run off. But that would take a recalibration of the wind speed.


I sure hope the upgrade can be self done, my SKY unit looks the same as the pictures above and my wind was all all the place, not to mention the rain is also giving bad readings. What is the plan to get the coating to everybody? or what would happen,


The app is BTST Ws Pro written by @btst.online. It is an Android app.