/ Altimeter queries - barometric vs GPS

This topic has been archived, and won't accept reply postings.
d80f0u on 15 Aug 2013
So after this year's trip to the Alps I think I'm sold on the idea of buying an altimeter watch, both for navigation assistance and for training purposes (i.e. one that can show rate of ascent in real-time as well as overall for the day etc). Been reading about barometric vs. GPS altimeters and although I understand the concept of each, I'm none the wiser about the practical pros and cons. In fact, the more watch reviews I've read the less decisive I've become! Anyone here with experience of both that can give me some advice? Just to make matters more complicated, I've also had a separate train of thought about buying a HR monitor (mostly for running). Might this be better as a distinct device or should I look for one that's built-in?

Thanks in advance!
highclimber - on 15 Aug 2013
In reply to d80f0u: if its calibrated properly at known heights during the day a. Barometric one will be a lot more accurate than gps. It will also warn you of falling pressure due to atoms coming in.
Axel Smeets - on 15 Aug 2013
In reply to highclimber:
> (In reply to d80f0u) It will also warn you of falling pressure due to atoms coming in.

Yeah those pesky atoms are nightmare out on the hill. ;-)
ice.solo - on 15 Aug 2013
In reply to d80f0u:

have a look at the suunto ambit.

its altimeter is baro based but gps fluenced when you turn the gps function on. apparently.
its quite smart and can sort of tell differences between height gain pressure changes. and it gives altitudinal changes in units of 3m (plus storm warnings and all that jazz).

got a HR monitor too.
needvert on 15 Aug 2013
In reply to d80f0u:

Not quite related...just got a foretrex 401. Wrist GPS with altimeter and electronic compass. Has options to display vertical ascent/descent m/min, barometer, amb pressure, sunrise, sunset, and a tonne of other things. It has some wireless ability and I here there's a cadence sensor addon, not sure about HR. Oh, and can show a graph of your change in vertical, either over time or distance.

Pretty popular in military circles it seems. Got it it new on eBay for a very pleasing price :)
Tom F Harding on 15 Aug 2013
In reply to needvert:

The foretrex 401 is not really a watch though.... How big are your arms?

http://i200.photobucket.com/albums/aa214/gruntipede/Random%20kit/IMG_1645.jpg

needvert on 15 Aug 2013
In reply to The_flying_climber:

Fair call....It sure aint small.
drolex - on 15 Aug 2013
In reply to d80f0u: I find barometric altimeters really useless when you most need them. If you need to retreat quickly because the weather is changing (not that rare in alpine environment), you have two factors influencing the measure (atmospheric pressure and change of altitude) and you don't have any reliable information anymore.

I personally prefer to have a somewhat imprecise tool, but that doesn't get mad when the weather changes.

If you have a lot of experience with them, barometric altimeters are fine I suppose.
seaofdreams - on 15 Aug 2013
In reply to d80f0u:
The best elevation tool is a map and when combined with the GS its very powerful. most gps' will give you data on your progress. HR maybe a limit, Iíve never looked for one

the map is a good weather indicator too - when the winds picking up it flaps around more and when its snowing it goes white </joke
m0unt41n on 15 Aug 2013
In reply to d80f0u: Barometric usually is more precise in terms of changes, but that depends upon the watch and algorithms it uses. GPS tends to give a better absolute value but not so precise. In my experience Suunto have much better altimeters, well maybe their algorithms are better. The Ambit2 has an amazingly quick GPS fix, far far better than the Garmin Fenix. But its "fused Altitude" where it uses Barometric and GPS to height doesn't give very good vertical speed. It has an option where slow changes in pressure are assumed to be weather, quick changes are because of moving up or down.

The old Suunto X6 had the best altimeter so far.
NottsRich on 15 Aug 2013
In reply to m0unt41n: Does the GPS function on these watches provide an output that is useful with a map, like a grid reference? If so, does that only work in the UK with OS style maps, or would it work abroad as well with different style map sheets?

From reading through the thread it sounds like the GPS function of these watches can be turned off, leaving just the barometric altimeter. Is that right, or have I misunderstood it? Is it only some models that allow that?

If the GPS can be turned off to save batteries when not needed, but when it is needed it provides a useful grid reference, then I might start thinking more seriously about them! I only really want an altimeter, but the GPS might be a nice-to-have sometimes in a whiteout on the plateu... I'm not really interested in anything else like HR monitors and compasses - any recommendations that would fit my description? Thanks!
jezzah - on 15 Aug 2013
In reply to NottsRich:
Have a look at the suunto ambit. You can turn on/ off the GPS option and it does everything it says brilliantly- you need a reasonably sized wrist for it to look good tho.

Jim Fraser - on 15 Aug 2013
In reply to d80f0u:

GPS and map is probably the right answer since there are fewer unpredictable variables.

GPS altitude is subject to considerable problems. It is highly dependent upon the amount of sky you can see and the position of the satellites in the sky. Some devices give you information that might help you in making an assessment about this but it's a bit sketchy. It will be affected by constellation reconfiguration much more than a GPS position.

Barometric is clearly subject to the atmospheric changes detailed above.

On a ridge on a nice day, both will probably give excellent service with proper service (settings/batteries) and intelligent interpretation.

Bad stuff doesn't usually happen when the sun is shining.
d80f0u on 18 Aug 2013
In reply to NottsRich: Your point about the battery life led me to thinking if that kind of watch is right for me after all - am I right in thinking that with GPS on the Suunto Ambit they only claim ~15hrs? I'm not sure this would fit well with multi-day alpine trips! I know you can turn off the GPS to save power, but if I'm going to do that I might as well not pay a premium for it. Does anyone know if a watch exists with altimeter / HR but no GPS?
d80f0u on 18 Aug 2013
In reply to NottsRich: I looked at quite a detailed review of the Ambit (www.dcrainmaker.com/2012/04/suunto-ambit-in-depth-review.html&#8206;) and the gist of that seemed to be that you have to plan ahead whether you want the GPS on or off, and can't switch it in on the fly. Can anyone confirm this?
andymac - on 18 Aug 2013
In reply to d80f0u:

Have a look at the Casio Pro Trek.

They are solar powered also.

Tbh ,I now question the need for even having these gimmicky watches.

Shiny toy syndrome.

Still going to get a pro trek though as it has the added bonus of being an everyday watch and not an overly fussy Star Trek type thing
NottsRich on 19 Aug 2013
In reply to d80f0u: Thanks for that link. If you're right about not being able to switch GPS on/off on the fly then I don't think that's right for me either!
Robert Durran - on 19 Aug 2013
In reply to d80f0u:
Obviously a barometric one is ethically purer.
m0unt41n on 19 Aug 2013
In reply to NottsRich: With the Suunto you have to turn the GPS on, in normal watch mode it is off.

The Baro altimeter displays pressure when stationary or nearly so and height when moving.

It will give a grid ref for a number of different systems, UK, UTM etc.

Compass is significantly better than all the previous ones I have seen, you do not have to have it horizontal.

Garmin Fenix will be better for location / hiking than Suunto.

I got the Suunto for running as well as hiking, it is much better than the Garmin at this.

m0unt41n on 19 Aug 2013
Euge - on 20 Aug 2013
In reply to seaofdreams:

> the map is a good weather indicator too - when the winds picking up it flaps around more and when its snowing it goes white </joke

Brilliant.. nearly choked on my apple :o)

Thanks
E
NottsRich on 20 Aug 2013
In reply to m0unt41n: Thanks for that summary, really useful.
Jim C - on 20 Aug 2013
>
> If the GPS can be turned off to save batteries when not needed, but when it is needed it provides a useful grid reference, then I might start thinking more seriously about them!

What is your impression of battery life of a GPS ?

I had mine on when I was driving around on holiday in the car, I forgot to switch it off one night and the next day, it was still working fine. I use rechargable batteries and I have never been able to walk long enough in a day to run out of power on the GPS starting with charged batteries.
Jim C - on 20 Aug 2013
In reply to Euge:
> (In reply to seaofdreams)
>
> [...]
>
> Brilliant.. nearly choked on my apple :o)
>
> Thanks
> E

But that is a weather indicator, not a weather forecaster.

ads.ukclimbing.com
balmybaldwin - on 20 Aug 2013
In reply to d80f0u:


Have a look at the Garmin Forerunner 410 (I have the older 405 version) good HR monitor, plus GPS tracking so will give you altitute too. baterry life is about 8 hours of GPS tracking, about a week whilst used just as a watch

This topic has been archived, and won't accept reply postings.