Smart watch / DA Charts

[Crews]

Is there any way to ascertain a Density Altitude value in the field from a modern smart watch like a Garmin or Suunto?

I am not looking for a smart watch with a full featured ballistic app, apparently that doesn’t exist just yet. A regular smart watch is something I would have on all the time no matter what. If I could somehow get a DA from it, I could keep some hard copy dope sheets based on DA in my hunting pack. Not for extreme distance stuff, more like 6-800 yard max distance. I currently use an app on my phone and a Weatherflow meter, works just fine. I’d like to have some redundancy but hesitate to spend the money on another dedicated piece of electronics (like a Kestrel.)

 

[xNF_9]

I have a Garmin Fenix 3 that has truflite ballistics in it. It does use use the current atmosphere to calculate the firing solutions. I have not tested to see how close the solutions are. Just some food for thought.

Below is the link to the watch app.

Truflite link

 

[Deleted member 113831]

If you are going to carry a paper chart then all you need is station pressure and temperature. Lot's of watches will give you station pressure and temp. You should be able to guess the temp to within 5 degrees or so anyway.

 

[Crews]

I have a Garmin Fenix 3 that has truflite ballistics in it. It does use use the current atmosphere to calculate the firing solutions. I have not tested to see how close the solutions are. Just some food for thought.

Thanks for the heads up, I'm going to look up some stuff on the Fenix 3 and see if I can use some of the other features and justify the cost.

If you are going to carry a paper chart then all you need is station pressure and temperature. Lot's of watches will give you station pressure and temp. You should be able to guess the temp to within 5 degrees or so anyway.

In my calculator (BallisticARC) I can switch between using either DA or Pressure/Temp/Relative Humidity. I usually just use DA because it's less numbers to write down in my data book for the day. Temp is no big deal. Regarding the RH portion, is it safe to assume from your feedback that it really doesn't make much of a difference at a max distance of 800 yards?

 

[xNF_9]

Thanks for the heads up, I'm going to look up some stuff on the Fenix 3 and see if I can use some of the other features and justify the cost.

I bought mine for $200 on eBay. It is kind of expensive if you only use it for just ballistics.

 

[Deleted member 113831]

Thanks for the heads up, I'm going to look up some stuff on the Fenix 3 and see if I can use some of the other features and justify the cost.


In my calculator (BallisticARC) I can switch between using either DA or Pressure/Temp/Relative Humidity. I usually just use DA because it's less numbers to write down in my data book for the day. Temp is no big deal. Regarding the RH portion, is it safe to assume from your feedback that it really doesn't make much of a difference at a max distance of 800 yards?

I use 50% RH at all times. It has never hindered me, even out to 2000+ yards. DA may be less numbers to punch in, but if you are using a chart to figure it, then it actually isn't faster.

Using the individual elements of Station Pressure, Temp and Humidity is actually simpler, and more precise. I can get an accurate station pressure and temp from my solar charged G-shock watch. I have been wearing mine for 12 years and it has never needed maintenance. I can get temp from the same watch or carry a small keychain hiking thermometer. I use 50% humidity at all times as I said before.

You get the same outcome with a properly calculated DA, but you are usually relying on either a device or a reporting station that isn't in your exact location to figure it for you. You can use a chart and figure it yourself, but then you've lost any benefit of simplicity.

See what I mean?

 

[xNF_9]

@Skookum may I ask which G-Shock you use? I’m a watch fanatic.

 

[Deleted member 113831]

@Skookum may I ask which G-Shock you use? I’m a watch fanatic.

GDF-100, probably the cheapest one with twin sensors. I'm probably due for an upgrade. I want a Riseman or something similar.

 

[Deleted member 113831]

This is probably my next watch, (Casio Protrek PRG330) I need the bigger numbers for old eyes.

 

[Crews]

I use 50% RH at all times. It has never hindered me, even out to 2000+ yards. DA may be less numbers to punch in, but if you are using a chart to figure it, then it actually isn't faster.

You get the same outcome with a properly calculated DA, but you are usually relying on either a device or a reporting station that isn't in your exact location to figure it for you. You can use a chart and figure it yourself, but then you've lost any benefit of simplicity.

See what I mean?

I see exactly what you mean.... keep RH at a constant value, and temperature is easy. All I really need is a watch that measures station pressure, and some charts to keep in my pack as a backup.

Is there any way you could help me with some examples of what your Temp/Pressure cards look like and how its broken down? Is it a different card for each distance? bracketed increments for temperature and pressure? I've been searching all around the hide but haven't found a good example of this yet. Everyone does cards with DA that I've found.

 

[Deleted member 113831]

Basically, I keep it as simple as possible. I run all my base line dope at 2,000 ft elevation and 60*F out to 1000 yards.

I run another chart for the same temp, but at 6,000 ft elev. and look at the deviation from my base line dope and record the difference at each 100 yards to 1000.

With high BC bullets travelling 2,800 fps or faster, you won't see a significant deviation till you get past 600 yards, then the difference will widen as you go out.

So maybe a 0.2 difference at 700 yds and a 0.5 difference at 1,000 yds. That isn't a hard trend to grasp, but it really helps to see it on paper. Now it is in your brain, instead of a device.

Next I go back to 2,000 ft elevation and do a chart at 100*F. Same principle, look at the difference from your baseline dope and notice the trend. Again, it won't even really start to deviate until you get past about 600 yards.

Once you have these 2 trends on paper and in your head, you can add or subtract the differences in temp and altitude based on your current conditions. You will be within 0.1mil of what your Kestrel says at all ranges to 1000 yds.

It isn't hard, but once you have it in your head, it can't be lost due to device failure. You also realize just how ridiculous it is to re-calculate your dope for every small change in weather. It really just doesn't change that much for a given location over the course of a day. And out to at least 600 yds or so, it most likely won't change enough to even dial or hold.

So that is the knuckle dragger way. This is how snipers used to use data books prior to ballistics apps. Now everyone relies solely on the apps. I use the apps to do the work that it historically took hundreds of shots to discover and understand. But having it on paper and in your head is still a very good idea in IMO.

 

[Crews]

So when you are referring to 2,000/6,000 ft elevation.... can I assume that term is interchangeable with station pressure in Hg?

I am getting what you're saying I think, Basically get some baseline dope from one common/expected set of conditions and expand with one variable at a time to establish how much delta there is and if it's even worth accounting for.

 

[Deleted member 113831]

So when you are referring to 2,000/6,000 ft elevation.... can I assume that term is interchangeable with station pressure in Hg?

Yep. I use standard pressure at altitude as a base line.

I am getting what you're saying I think, Basically get some baseline dope from one common/expected set of conditions and expand with one variable at a time to establish how much delta there is and if it's even worth accounting for.

Exactly.

 

[palmettoman]

I guess its good I live in FL... ballistics are simple

Elevation: 0 (not counting landfills)
Temp: 100* (between May and November)
Humidity: 100% (seemingly always)
Wind: See which way and how fast the mosquitos are flying

There's a reason this place used to be a penal colony. Yes, I kid, but only slightly...