Suggestions for an altimeter?

My mind just did some real gymnastics trying to imagine driving in traffic while focusing on a VSI !!! What a great forum for blowin' my mind when I'm in the mood!

 

REI has larger altimeters that you could mount. As noted altimeters are a pain because you have to “zero†them all the time to account for changes in barometric pressure. On the other hand they can be quite accurate. I had fun with the Boy Scouts when I as an Assistant Scout Master using a watch type altimeter. I would make elevation profiles of our trip from the topo maps. I could then set and reset the altitude at the start and middle and end of the day also at rest stops if there was a front coming through. Then when we got the inevitable “how far to the top of this hill†or “how far till we camp†I would glance at my watch altimeter and my card with the elevation profiles and position and I could tell them “1/2 mile to the top†or “4 miles to camp†. The old scouts would smile and the new ones were sucked in to a Socratic discussion of maps, navigation aids and route finding and pretty soon we were there.

 

:blink: Forget all these fancy electronic devices. I'm just gonna get me a line level from Home Depot and mount it in the car where I can see it. That should tell me if I'm going up or down. After that all I will need is a device that tells me if I'm coming or going. B)

Matt
Denver

 

One way to do what you want would be with a barometric pressure type altimeter/barometer. Peet Bros makes a nice one. It's analog and is extremely accurate if you do your part. You'll also need to be able to guesstimate where the needle is in the 20' increment. I've had mine for years and don't remember what it cost. I got it from LL Bean. Batteries not required, no satellites either. I wear it around my neck to protect it from shock. Protect it from blast and it'll last a very long time. You'll need a topo map and know how to use it in order to wring top accuracy out of this unit. As barometric pressure changes the accuracy "shifts"; the more known elevations you encounter the better the accuracy (more places to adjust for changing barometric pressure). This unit is quite light and is quite an instrument. It can be used for more than just altitude as it's also a barometer.

My Magellan Platinum is also very accurate. Easier to use, but requires batteries.

If I was hiking away from batteries I'd opt for the Peet. For day hikes where weight wasn't a consideration, the Magellan. If I was hunting I'd leave the Peet at home, blast from the shot will destroy the mechanism over time.

 

I have an Avocet ski watch and GPS. Both are accurate +-20 feet at best. The watch drifts with time, temp and barametric changes.
I've seen hardware store ads for a digital level, forgot the price.

 

I recommend my Garmin GPS V to anyone who does not have the navigation package and/or wants accurate elevation data. When activated in WAAS mode mine gets to about 7 feet accuracy. The unit comes with a nice dash mount, which has both a permanant and temporary adhesive option. I will try and post some pics tomor. night of where I chose to mount the unit and its readability from sitting back in the drivers seat. Also for about $230 bucks it is great in the woods or on long overseas trip with the simple upload of new software for each continent. Don't waste your money on the innacurate complicated watches. I own a Suunto and an Avocet. Both sit at home on the dresser since they are both as big as the original TANDY LAPTOPS.

 

CHECK SPRUCE AVAITION I'M SURE THEY HAVE A WEB SITE, OR AN 1800#...

 

"Seems when I shop around.. the only ones I can find are included in the gps's. I don't want to buy a whole gps just for the altimeter and its not that accurate anyway. And I don't want some ugly clunker mounted thing either."

Ugly clunker.... I can buy a garmin gps which is three times as accurate as the integrated unit, can take it with me, and it is waterproof for a little over 200 bucks. Then I can hit 2 cars in a parking lot and run over a parking block and my insurance premiums won't go up near up as much as the $400 premium they charge for the back up camera. But the integrated unit sure looks cool and is sure to tell you if the ground is flat. You can obviously see I only bought my Prius for the engine and not the accessories that are marked up 200% by Toyota.

 

Actually, my Magellan reported a change of 100 feet as I walked along a perfectly level street. And someone else in this thread reported a GPS that would jump around by 20 feet while standing still. Precision does not mean consistency! It just means small units in the read-out. What Windstrings needs for his application is consistency, and satellite-based GPS do not deliver that.

 

The Garmin comes with a mount that is so easy to remove, I do it in approximately 5 seconds. The adhesive stays but the mount and the gps detach with the push of a quick release. It looks pretty good when mounted on the dash, and despite its 22000 mile variance, is able to tell me when I am going up or down a hill quite accurately (precisely). I use Nimh batteries which are recharageable and last about 8 hours on normal. 99% of my is driving where I don't even need a GPS, so batteries are not a concern. I understand this still doesn't help the flat ground question. The Stanley level one member posted seems like my best solution. I may buy one tomorrow.... Pictures will follow....

 

I've posted this umpteen times, so my apologies for the repetition...

"I can buy a garmin gps which is three times as accurate as the integrated unit,"

You mistake actual accuracy for the error figure the handhelds often give. The latter is NOT the absolute accuracy, it is the "estimated error" contributed by poorer-than-ideal sat geometry, which varies over time. This is in addition to the uncertainty erros which are on the order of 25 meters. Without DGPS augmentation, accuracy better than this is not possible.

Also, your Garmin lacks the turn gyro and odo inputs that allow far better map-matching in the DVD system used by the Prius

Don't get me wrong, the portable units are plenty accurate for road navigation, and have the portability advantage as well as easier (or at least cheaper) updatability. But let's not overstate the accuracy.

 

I had searched for a long time for an altimeter myself. I tried a GPS-based one made by a British firm (found it through Google) but it does not update often enough to be useful (every 30 seconds or so). The best that I found so far, however, is a Suunto watch that I had almost abandoned. The altimeter is dependent on barometric pressure (so, when I see my garage altitude changing up and down every morning I can tell whether the pressure is going up or down; it also reads pressure directly). You can easily set it to the altitude of your starting point (e.g. my garage is at 1100 feet) and then it updates every 5 seconds, which is great if you leave in a town that has a lot of hills.

 

my GPS measures altitude but can only be used for comparative purposes only. its not accurate. when crossing the Nisqually flats, i should be a few feet above sea level, (i realize "sea level" is a relative thing) and it always reads about -34 feet. obviously not that far below sea level. at other places that are "known" sometimes im fairly close, but generally im usually 50-150 feet low.

but i have seen changes in elevation contrary to what i thought i was doing. of course, my instantaneous mileage readings on my Prius also tell me whether im going up or down too.

 

Thank you for this, because it explains something about my hand-held Magellin eXplorist: I've used it to track my route while hiking on a trail, out and back, and then transfered the route to the computer and put it on the topo map. Once the unit has found 5 or 6 satellites it generally claims less than about 20 foot error, but on the map there can be a couple of hundred feet between my path out and my path back, even though I was on the same 3-foot-wide path both ways.

You've explained why this happens, and I appreciate it. The unit, by the way, seems to me more a toy than anything else. Geocaching with it could be fun, but I don't think I'd trust it in an emergency. It adds weight, and I cannot hold it and my hiking poles at the same time.

The Street Pilot is another matter entirely. It gets me around this confusing town like a charm. Of course, I never event look at its altitude reading, as that is on a different screen, and I always have it showing the map. Might be interesting, once or twice, to compare its altitude with the topo map. But even then, if there's a discrepancy, the topo map could be wrong as easily as the GPS. According to the Magellin and its topo map, I once kayaked across dry land while on Lake Kootenay.

 

Hi Daniel,
'Consistency' is a good way to describe precision. Wikipedia has a very nice graphical representation of precision and accuracy.

That said, if the requirement is knowing true change in elevation over relatively short distances, I'd try a precise instrument first. If Google maps is accurate, a couple of field tests will tell you if the device does what is desired of it.