Give your $.02 on Altimeters

[Desey]

Here's mine....

Have used both the Suunto Vector and the Timex Helix. Both are okay. The Timex is MUCHeasier to use and has a cool "lock" to keep from jumping screens. My main complaint is that these altimeters must be recalibrated at known altitudes along the way or they get pretty inaccurate. Well, if I knew the exact altitude I wouln't need an altimeter in the first place????

 

[ChrisT]

I have the Nike ACG Ascent watch with altimeter and I like it a lot. Yes, I have to re-calibrate altitude daily if I want accuracy but as far as following my increase in altitude along the way, if I'm on a hike for example, it seems pretty accurate. From what I understand, no altimeter is 100% accurate unless you get a GPS.

[philfort]

I don't think GPS altimeters are nearly as accurate as a (properly calibrated) barometric altimeter. That's why some GPS's have baro altimeters in them (like the Summit).

But I guess they're quite a bit better than they used to be now that selective availability is off.

[snoboy]

Unless you can stop the weather from changing, you are always gonna have to reset your altimeter!

 

I find the one in my eTrex summit good. I was on a car once. playing with a fancy aneroid Thommen one. The needle jumped about 5 feet when you opened the window! Pretty sensitive.

 

I still use my altimeter between known points. I will assume you are joking?

[ChrisT]

If I start at 6000' and I know the summit is 12,000' or so...it helps me track my progress along the way...as I'm huffing and puffing along.

[Geek_the_Greek]

I've got an older (3-4 years) Casio Twin Sensor watch. Does what I want it to do - give me the altitude within about 100-150 feet or so. It has other features but I don't use them. I imagine there are better units out there, but I like mine just fine.

[snoboy]

If I start at 6000' and I know the summit is 12,000' or so...it helps me track my progress along the way...as I'm huffing and puffing along.

 

And further, if you start at 8AM at 6000', and you are at 9000' by 1PM, you might wanna think about turning around... nad going to the

[ChrisT]

yep but that's not me!

[cracked]

I wonder why it is that GPS can measure Everest to be 7 feet taller than previously thought, but the commercial GPS units aren't very accurate altimeters. Something to do with # of satellites the thing picks up?

[Jake]

Wasn't it originally a system developed by the military? Didn't they "dumb" down the precision of it so unfriendly people or countries couldn't get an exact position on something if they wanted to blow it up or something? However, I thought they relaxed these guidelines a year or so ago so all GPS was very accurate. I'm not sure that GPS systems ever use more than 3 satelites to get positions, either. But, I may be totally wrong on all of this too.

[snoboy]

Jake - consumer GPS use 4 if they can, 3 is not as good. The "dumbing down" or Selective Availibility was turned off. You are mostly right.

 

cracked - I think that they use better receivers, they probably don't have any mountains blocking sattelites and they probably do a couple of tricks to improve accuracy.

 

One could be averaging, basically taking many fixes, and averaging them. They might also use Differential GPS. This basically consists of a very accurately surveyed point with a receiver that records the difference between where it is (the surveyed position) and where the GPS thinks it is. This can then be aplied to the data from the unknown point, either in real time, or post.

 

These are my guesses. Most importantly, I don't know if either of these tecniques would have a benefit on the quality of an altitude fix.

 

I think there is someone (iain?) on this board who knows a fair amount about GPS, and can probably tell you much better...

 

I thought it was funny a few years ago when I read in a trip report that the group had found the map to be in error, because the GPS showed the height to be a few feet diferrent!

[Cpt.Caveman]

I have had some different alt. I like the suunto vector. I reset it about once every month. Works good enough. The only times I rely on it are when I am in whiteout conditions and then will set it daily to known altitudes if I can. Never had a problem. Nothing is completely accurate out there if you dont set it daily I guess.

 

Using the Suunto is not simple all the time ie setting alarms and other things. It's a cool tool (altimeter) but like anything else it's not foolproof. At least with the suunto you also get a compass and alarms for alpine starts. I rarely use the alarm since my alpine start is often after dawn in summer.

 

I dont want to downplay one of my other altimeters I had on a sony watch from years ago other than you had to set it every day which is high maintenance. It was often more innacurate or off than the suunto. If it's too high maintenance then I usually dont like things

[freeclimb9]

I've got an older (3-4 years) Casio Twin Sensor watch.

I got one of those too. It's got everything. A barometer, an altimeter, a thermometer, a chronometer, a calendar, and this thing that tells time. The altimeter goes in increments of 20 ft, and it's not super accurate. But it has got me to pass elevations during long traverses pretty well. What else do you need?

[cj001f]

I've got a Thommen - it's very easy to reset (turn the dial) very reliable, and doesn't need batteries - great for trips longer than a weekend. I have been looking for something a bit more "modern" lately - like a Brunton Sherpa, or a Suunto Altimax (I didn't like the compass on the Vector I owned for a short time)

[fern]

you need a minimum 4 sattelites to get a GPS based altitude. It's like triangulation in 3 dimensions, 3 satellites find your 'sea level' location on a map and 1 finds how high you are above it. I say 'sea level' but it's not really sea level. GPS altitudes are relative to the Geoid or something like that which depend on the local gravity field which is distorted by such things as mountains(!) blah blah blah ... I can't be bothered to lookit up but I got an A in the course

 

I have a Casio Pathfinder that I got at Costco. It is big and make me look outdoorsy. . Altitude accuracy suffered somewhat above 5000m but so what.

[philfort]

Here's what looks like an old FAQ (since they mention SA *might* be turned off in the future):

http://vancouver-webpages.com/peter/gpsfaq.txt

 

1.3 What accuracy can I expect?

1.5 How do some users get centimetre accuracy?

2.3 Why does the reported altitude vary so much?

 

 

I use a Pete Bros. analog altimeter. Often I don't take it because of the weight - I should probably get a watch. But it is easy to calibrate, just turn it.

Edited February 5, 2003 by philfort

[Dru]

if you are on the summit and still dont think you are high enough there are herbal remedies to help with that.

[leejams]

I have that Nike ascent as well. Good unit. However, had it about a year and now needs a new battery. Chris T have you ever changed the battery? Damn if I can figure out how to open it up.

[ChrisT]

Unfortunately you have to take it back to REI or where ever you bought it so that they can send it in to repair for new battery. You can't do it yourself from what I understand. Mine is due soon too.

[EJohnson]

I have been using Avocet altimeter for about 6 years. Couple of things I don't like about it is. You need to send it back to the company for battery replacement $20 + shipping. The other is like many of altimeter watches, they are big and easily snagged. A better setup might be using lanyard (around your neck).

 

Erick

[leejams]

chrisT, thanks for the advice. I will give REI a shot at it. Kinda frustrating as I have only had it a year and sputtering out allready.

[COL._Von_Spanker]

Regarding the compass feature on the Vector: It's nice for quick stuff, to get my general orientation, but I found it to be sort of cumbersome to use to navigate in a whitout when compared to a 'classic' compass. Basically when I need a compass I want a real compass where I can see the whole dial.

 

I like the altimeter, again it's more of a convienience though. and when calibrating it's usually pretty easy cause the trailhead often has a published altitude.

 

The bottom line is even if you never use it, you gotta have one to join the secret brother/sisterhood of alpinists, it's like knowing the secret hand shake, right guys?

[Attitude]

I have a Suunto Altimax and a Garmin eTrex Summit.

 

I bought the Altimax (without the electronic compass) because it was cheaper and I heard that the compass really sucks the batteries. It works great, but I usually forget to calibrate it at trailheads or reset the cumulative gain function. The alarm sucks because it is not loud enough.

 

The Summit also usually needs recalibration at trailheads unless there is a clear sky (clear of mountains and heavy forest). The detected satellites need to be far apart in the sky for the altitude measurement to be accurate (or position, too). Typically, the GPS is much more accurate on a summit than halfway down the side of a ridge or in a valley There is a screen which shows the location of the satellites in the sky.

 

[Cpt.Caveman]

It's nice for quick stuff, to get my general orientation

 

Anybody who thinks they can navigate long distances through the bush with absolute accuracy or similar conditions would be an idiot. Of course it's not as good as a old fashioned compass but I and many others I would guess less than often carry real compasses... .... ... ..

[COL._Von_Spanker]

Very true...