 Poster: A snowHead
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What's the best altimeter these days, primarily for off piste/touring navigation? Needs to be easy and clear to use and accurate and not need regular re-charging
Although GPS would be nice it doesn't seem worth the trade off in battery life
Suunto Core seems good (latest version), any other or better suggestions?
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Obviously A snowHead isn't a real person
Obviously A snowHead isn't a real person
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@On the rocks, If you are going to trust your life to an altimeter I wouldn't, I wouldn't trust the Suunto Core.
The Core altitude indication is air pressure based, so if barometric conditions are changing during the day, the indicated altitude will change without you moving. You also need to reset your base altitude at the start of any trip, every day, to have any hope of accuracy.
I have reset my base altitude, based on a OS map, walked up 2 floors, and had at accurate 6m altitude change. I have then gone out wearing it for 3 hours, and returned to a 50m plus altitude difference at the same location.
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Well, the person's real but it's just a made up name, see?
Well, the person's real but it's just a made up name, see?
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I use a Suunto Ambit3 Peak, which I find very reliable and accurate, if somewhat user-unfriendly. I previously used a Suunto Observer for about 5 years before it started leaking (albeit it had a very hard life!). The Ambit3 Peak includes GPS, but can still deliver 100+ hr battery life using GPS which is enough for me. Or with GPS off you get 200h+
Re altitude measurement – I’m not aware of any more accurate approach than air pressure. GPS altimetry is much flakier in my experience. 50m change based on weather is not unusual. The Ambit3 can self-calibrate based on GPS when it thinks it has a really good signal, but I don’t find this much assistance.
Personally, I find altitude invaluable for mountain navigation, particularly in snow.
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| Quote: |
| . You also need to reset your base altitude at the start of any trip, every day, to have any hope of accuracy. |
When relying on one for navigation you recalibrate much more frequently than that, sensibly at regular intervals when at known points of altitude from the map.
It's a well used and tested method of navigation as long as correct procedures are followed eg https://thrive-outdoors.com/2014/03/14/altimeters/
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Anyway, snowHeads is much more fun if you do.
Anyway, snowHeads is much more fun if you do.
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Polar v800, and I'm pretty sure other gps enabled HRMs with barometric altimeter have things done similar way, don't really need calibration. It's still advisable to do it, if you need exact position, but in general watch calibrates itself with help of gps, and it's done through the session so air pressure changing through the day doesn't influence altitude measurements of the watch. While based on my own experiences, v800 is super accurate, I still wouldn't trust my life on it's measurements 
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I've got a 'Core' and it's ok. As others have said you need to reset as often as possible if you are navigating seriously. My phone GPS seems to be pretty accurate as a cross check, assuming there are a few satellites.
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I've been using Suunto Observer for past 10 years or so. It's good, when used appropriately.
I agree with snowdave that GPS altimetry tends to be flakier, and with geoffers that barometer altimetry requires frequent re-setting of height at known spot heights during the day. Knowing, and working with those limitations is the important bit - and knowing altitude is really useful for navigation on snow.
I will likely get another Suunto when the Observer eventually dies - but it's a robust, reliable bit of kit.
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Not that an iPhone is a sensible piece of survival kit, but I wonder how one compares with a 'real' altimeter.
I have an altimeter app that can offer you altitude based upon map position (derived from GPS), GPS altitude (more accurate than I'd expected, but not perfect), or change in atmpospheric pressure (which I think is regularly recalibrated by METAR messages from the nearest weather station - although I could be wrong about this)
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You'll get to see more forums and be part of the best ski club on the net.
You'll get to see more forums and be part of the best ski club on the net.
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I have one of the old fashioned aneroid barometer altimeters used by field surveyors for decades. It is about 150mm across, brass and pretty heavy. It shows alitude in feet on an anlogue dial and has a fairly complex calibration system. This was the type used by mountaineers until the digital ones from the likes of Suunto came along. It was probably the way that much of the detail contouring was done on maps in the mountains. One advantage of the analogue dial is that you see immediately the likely precision of the instrument. In all other respects the digital "watches" completely knock it into the museum.
In fact they are amazing pieces of equipment. They last for years on one battery, sit on your wrist where you can easily consult them, very, very accurate (probably more so than the map), so light weight that you do not have an excuse for not having one and remarkably inexpensive.
Satellite based altitude is not very accurrate due to the configuration of the satellites and hand held receivers and mobile phones are in IMHO too reliant on short battery lives to be of use other than as an entertainment. I have to confess that I use viewranger a lot and love the program, but in the French mountains I use the Suunto for elevations and the phone to see where I went to before the battery ran out.
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| PowderAdict wrote: |
@On the rocks, If you are going to trust your life to an altimeter I wouldn't, I wouldn't trust the Suunto Core.
The Core altitude indication is air pressure based, so if barometric conditions are changing during the day, the indicated altitude will change without you moving. You also need to reset your base altitude at the start of any trip, every day, to have any hope of accuracy.
I have reset my base altitude, based on a OS map, walked up 2 floors, and had at accurate 6m altitude change. I have then gone out wearing it for 3 hours, and returned to a 50m plus altitude difference at the same location. |
I second that - wore my Core last weekend in Zermatt - Saturday blue skies, Sunday overcast - the reading at 3000 m altitude had a difference of circa 100 m on the same spot simply because of air-pressure changes
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snowHeads are a friendly bunch.
snowHeads are a friendly bunch.
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I'm a professional mountain leader/guide have been using my Suunto traverse for a while now. It has GPS which can be handy but works for weeks on one charge if you are not using the GPS function that much. The altimeter function can use barometric sensors as well as the GPS and does not chew the batteries. For example it was fine for the whole length of our Pyrenees Haute Route trip this summer and proved very handy (and if you are worried about the barometric reading you can always turn on the GPS for a sure fix).
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And love to help out and answer questions and of course, read each other's snow reports.
And love to help out and answer questions and of course, read each other's snow reports.
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When I used to do a lot of high altitude climbing (in the Jurassic era) we just used Thommen analogue devices. Worked fine for us, recalibration took a few seconds and didn't need batteries
Incidentally, how good are all these modern electronics in extreme cold temperatures (i.e. -30, -40) ? Surely battery life must be a real issue. If you're just out for the day I'd imagine that's fine but not when you're out for several days or more I'd be concerned
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@dsoutar, the Suunto watches have excellent battery life (although I cannot speak for those with gps). Mine needs a new battery every 6-12 months, depending on how much I use it. And it's fine in low temperatures.
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You know it makes sense.
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Thanks everybody
it seems that barometric altimeters are the most accurate and reliable but obviously need frequent calibration if relied on for critical navigation, either manually using map data for spot heights, huts etc or automatically using GPS
I'm still leaning towards a stand alone altimeter relying on regular manual calibration that I can be sure of rather than the auto GPS. (I can always switch on my phone briefly if I need a lat and long fix or even GPS altitude check), I would expect the stand alone Suunto Core to be simpler to use than the Suunto Ambit which some reviews indicate is a faff to use
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Otherwise you'll just go on seeing the one name:
Otherwise you'll just go on seeing the one name:
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The Core (and equivs) are definitely easier to use. If you want to know _exactly_ where you are then the Ambit is vastly better because of GPS and waypoints (e.g. complex exits or entries can be pinpointed on a satellite map and uploaded to the device). The prices of the two are similar (I think my Ambit 3 was £180, and my wife's Ambit 2 was £50 from ebay).
I think you can set up a free account on the Suunto movescount website and have a play to see what you think. The online mapping tools are very impressive - set up route on google maps or any of the multitude of topo maps they have, and then upload this to the Ambit3 over bluetooth. Similarly, download what you skied at the end of the day.
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Poster: A snowHead
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@snowdave, Yeah, I don't know about other spots but there is more detail and trail info on the open sourde maps the movescount app uses than on the official IGN maps!
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Obviously A snowHead isn't a real person
Obviously A snowHead isn't a real person
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GPS height channels are not very accurate when compared with position on the earth, +-400 feet is not unusual and therefore should be treated with caution as a navigation aid. The aneroid measurement in watches is measuring the rate of change of pressure, which is fine on a stable pressure day, but if the pressure system is dynamic then it needs recalibrating regularly against a known height, otherwise its next to useless.
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Well, the person's real but it's just a made up name, see?
Well, the person's real but it's just a made up name, see?
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| chocksaway wrote: |
| GPS height channels are not very accurate when compared with position on the earth, +-400 feet is not unusual and therefore should be treated with caution as a navigation aid. The aneroid measurement in watches is measuring the rate of change of pressure, which is fine on a stable pressure day, but if the pressure system is dynamic then it needs recalibrating regularly against a known height, otherwise its next to useless. |
The aneroid system is measuring absolute pressure, not rate of change of pressure. It only knows rate of change by comparing absolute pressure readings at known time intervals.
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@snowdave, I should have said display (in height units) the change in pressure - it was late!!
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Anyway, snowHeads is much more fun if you do.
Anyway, snowHeads is much more fun if you do.
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@chocksaway, On the GPS, is the accuracy dependent on the number of satellites visible or is there a software element ?
Anecdotally I suspect that some software is better than others. For instance the GPStest app seems to return pretty accurate heights (I ended up using it in the lakes on Tuesday and it proved handy) while some of the activity trackers seem much more flaky, returning differences in the region you mention.
I tend to try get a fix for both GPS and Watch against a known map point to see where they are ( so to speak ! ).
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You'll need to Register first of course.
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My baby Garmin has both pressure and GPS sensors. It knows that the pressure can vary slowly because of barometric changes and it knows that the GPS height calculations are noisy. It uses a combination of both, by slowly correcting the pressure signal using a smoothed version of the GPS signal. Clever!
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@AndAnotherThing.., I think the short answer to your question is 'geometry'.
The longer answer is here : http://gpsinformation.net/main/altitude.htm
Maybe it's my imagination, but I wonder whether we also perceive vertical accuracy to be even worse than it actually is partly because we roam far less in a vertical plane than we do in a horizontal plan, and also because we can more easily quantify it. With horizontal accuracy a GPS might show our position as being near (10m) a rock. We can see the rock very close to us and we think that's pretty good. Now, the map tells us that the rock is at an altitude of, say, 100m asl. Our GPS tells us, on a good day, that we are at an altitude of 115m. That's a 15% error and the nearest place on the map at that altitude is 2km away. Ouch! (Obviously we are currently rambling in Norfolk at the moment!)
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@AndAnotherThing.., I think I'll let Garmin answer that one
https://support.garmin.com/faqSearch/en-GB/faq/content/QPc5x3ZFUv1QyoxITW2vZ6
Of course, the more money you spend on a receiver the better it will be, but it will chomp more power and be bigger. Likewise, if you are close to the bottom of a high steep arête some sattelites will be blanked.
Hence my dislike of I phone navigators and ski apps (which spend a good deal of time talking rubbish), you have to understand the limitations of the system you are using despite the apparent accuracy because of a digital display.
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You'll get to see more forums and be part of the best ski club on the net.
You'll get to see more forums and be part of the best ski club on the net.
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| Quote: |
(Obviously we are currently rambling in Norfolk at the moment!)
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I didn't even realise that Norfolk was that high!
Altitude is actually much more difficult than it seems. We often see the term asl or aod but what do they mean? In Great Britain sea level is taken as above the Newlyn datum in Cornwall. In Northern Ireland it is the Belfast datum. Due to variations in the Earths gravitational field and our assumptions about the shape of the Earth these are different. To confuse the matter even further heights in Ireland prior to 1970 referred to the spring low water mark in Dublin bay, about 2.7m lower. So check on your map what you are expecting, especially if building a tunnel between GB and NI.
In continental land masses it gets even trickier. I did some work a few years ago on a digital elevation model for the Punjab and discovered that one map sheet (a source of secondary data) was a couple metres lower than every where around it.
To imagine why GPS heights are never going to me as accurrate as x,y corrdinates consider the angles subtended at the observer from GPS (or GONAS or other navigational satellites) For x,y the angle beween satellites is typically 60 degrees, this enables triangulation to work well, but in the vertical plane this angle is only a few degrees hence trickier to determine where they intersect.
And we will not even dicuss the acurracy of the map in terms of the elevation. When using something like the Viewranger software the program has the option of giving yout either the GPS height or th eheight from the x,y corrdinates recored on the map. In most cases this is what you actually want for navigation. It is also what you are getting from the barometer which you are calibrating not to true height (whatever that is) but to the height on the map.
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@johnE, There's also the problem that pressure is not even around the Earth (not a result of g, but of the difference in atmospheric thickness at the equator and poles). I've climbed Kinabalu (on the equator) where my altimeter under-read by about 100m despite being perfectly calibrated at sea level. You can't calibrate for this issue because the gradient of the pressure/altitude relationship is different. It is the inverse at the poles; altimeters read too high due to the lower air pressure at a given altitude.
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snowHeads are a friendly bunch.
snowHeads are a friendly bunch.
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Is it not... that you need to be a little intelligent to use all of these systems? In olden times we had traditional altimeters for hang gliding and climbing, but you would naturally be aware that those devices have their limitations and use them for *part* of your input data.
Using an altimeter to make a route-finding decision is pretty rare. I doubt you'd do it without corroboration unless you really had no choice.
Technology toys are fun, but they don't replace grey matter. They're probably mostly useful for taking down the pub so people can be impressed with how much vertical you did, or perhaps I just mix with the wrong sort of people.
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And love to help out and answer questions and of course, read each other's snow reports.
And love to help out and answer questions and of course, read each other's snow reports.
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| johnE wrote: |
| In continental land masses it gets even trickier. I did some work a few years ago on a digital elevation model for the Punjab and discovered that one map sheet (a source of secondary data) was a couple metres lower than every where around it. |
I recall setting the watch at the bottom of a tall cable car in Zermatt and finding it had drifted by a few tens of meters by the time we reached the top. Known map heights top and bottom. I put it down to local atmospheric conditions(?) but as the other posts has said, you have to treat all of these as a guide rather than as an absolute.
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@philwig,
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Using an altimeter to make a route-finding decision is pretty rare.
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Guide books frequently say things such as "turn south west at 2850m". Though not essential, when climbing in the Dolmites, on routes that are often a couple hundred metres high, it helps me know where I am on the climb, especially if I have failed to keep to the guidebooks reccomended stances.
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You know it makes sense.
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@johnE, I agree. Often my altimeter is my primary navigation device. If you're on a known line with a decent amount of gradient change - be it climbing route, gully, ridge or trail, then an altimeter gets you to a single point on that line with better accuracy than triangulation.
In contrast, in a flat place like Norfolk, triangulating off church steeples is going to be a lot more accurate!
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Otherwise you'll just go on seeing the one name:
Otherwise you'll just go on seeing the one name:
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@snowdave, said...
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| If you're on a known line with a decent amount of gradient change... |
...also, by following a known altitude in a whiteout (similar to navigating on a known depth in fog when sailing).
From a Himalayan climbing lecture a while back: the climbers left their tent for the summit bid in a whiteout, having measured their altitude before leaving. The only hope they had of finding the camp on return was to aim off (ie follow a bearing well to one side of the tent) until they hit the known altitude then follow that altitude back to the tent. Obviously terrain dependent in this case, but must have worked for them... 
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Poster: A snowHead
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| in garbure we trust wrote: |
| I'm a professional mountain leader/guide have been using my Suunto traverse for a while now. It has GPS which can be handy but works for weeks on one charge if you are not using the GPS function that much. The altimeter function can use barometric sensors as well as the GPS and does not chew the batteries. For example it was fine for the whole length of our Pyrenees Haute Route trip this summer and proved very handy (and if you are worried about the barometric reading you can always turn on the GPS for a sure fix). |
An update, after lots of research Santa went for the latest rendition of the Suunto Traverse Alpha which has all of the real world benefits and none of the real world drawbacks, not least minimum faff factor.
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Obviously A snowHead isn't a real person
Obviously A snowHead isn't a real person
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I have a Suunto Traverse. But can someone enlighten me of the advantages over an apple watch, apart from battery life?
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Well, the person's real but it's just a made up name, see?
Well, the person's real but it's just a made up name, see?
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I have a suunto observer, I do use the altimeter, rather than keep resetting it I tend to just hold the deviation in my head, but will reference it often, this can also give a warning of a change in the weather.
In practice I’ve very rarely needed super accurate altitude measurements for navigation, maybe occasionally on a glacier in poor vis. I mainly use my altimeter watch for gauging my progress, ie climb rate, or metres to the top.
Over time. I’ve used map and compass, garmin devices etc but I tend to use my iPhone as first resort these days with a map as back up. I have a battery case so it lasts a couple of days even with heavy gps use. My current favourite digital maps are, Fatmap for skiing, the MapOut app, the free Swiss os maps, ING in France which aren’t great, and of course the UK OS maps.
I occasionally use the aim to miss technique described above but never with altitude as a trigger, I’m impressed.
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