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Stan
03-24-2005, 03:45 AM
A question for any other ridiculously hopeless gear-heads:

Anybody have experience with the Suunto units? Does the altimeter measure altitudes constantly or in timed periods? Altitude accuracy? Compass accuracy? I have recently tried one of the Timex Helix units, but it doesn't fit my wrist all that well nor do I like the altimeter - measures in timed periods and I haven't seen very good accuracy.

Stan

Kevin
03-24-2005, 04:24 AM
I have a Tissot T-Touch, with compass, altimeter and barometer. It also is a lot smaller than the Suunto, but more expensive. There are many on ebay.

It looks like a regular watch.

The altimeter runs on barimetric pressure, so it will change as you move. Don't expect it to be that accurate as an altimeter, but it's pretty good as a compass. The altimeter will change with fronts coming in, and needs to be recalibrated when you know the altitude.

Shawn
03-24-2005, 04:32 AM
I've got the Suunto Observer in Titanium. Very gimicky and I wish I had the 300 bucks I spent on it back. I don't think it is inherently very accurate, I've never seen it really far off in terms of altitude, but it requires frequent calibration. The compass on it is pretty cool.

Do you have a GPS? You can get all those things on a pretty cheap GPS unit. I don't like getting altitude measurements from a barometer/manometer, for reasoning to long to type this early in the morning.

I would get a good GPS, and forget the pocket altimeter.

Stan
03-24-2005, 04:42 AM
I'll check it out Kevin, thanks. You haven't convinced Victorinox to build one attached to the Huntsman knife yet?

Based on lots of experience with bar. altimeters, the Helix should be more accurate, but I may have a lemon. I should send it back. The timed readings deal is no good for rapid ascents or descents. I once saw a friend's older Casio wrist-altimeter that was incredibly accurate - that model was discountinued - don't know how the current Casio's stack-up.

Stan

Stan
03-24-2005, 04:53 AM
Thanks Shawn. Bar. altimeters do require frequent recalibrating especially during weather changes, but that's why I like to have one - for weather prediction. Can't do that on a GPS, unless you have a model with a bar. alt. I prefer to keep the 2 units seperate for my own idio(t)syncroncies of use...

Stan

Kevin
03-24-2005, 05:06 AM
Stan, the value in the Tissot is that it's a darned good watch, too. It also has a feature that allows you to see if a high or low pressure front is coming in, as it monitors the change in barometric pressure over the past 8 hours.

All things considered, a slick design. For the price of maintenance on a Rolex, it's a much better watch. I never will need anything better.

Sundles
03-24-2005, 06:13 AM
OK, now you are going to know I'm really an old curmudgeon, but when you are high, you know you are high. WHen you are low, you know you are low. When you are in between, you know it. If you think you are headed north and you arent, you will find out soon.

I dont understand the desire or need for such stuff, especialy GPS units in the wilderness.

Ed T
03-24-2005, 06:31 AM
Stan,

I have or have had Suunto, Hi Gear, Freestyle, Nike, Timex, Polar and Avocet. Of all, I like the Avocet the best, although it doesn't have a compass function. It is small sized and you could get (don't know if they still have them) a neck lanyard in place of the wrist band. They also come with two wrist bands, a regular plastic and an elastic band. Very easy to use. Accumulated elevation is very accurate, Calibration is simple. Only drawback is they want you to send the watch in for battery replacement. I am starting my third year on the origional batteries thou.

My 2nd choice is the Suunto. It works as well as the Avocet, has the compass, (which needs to be level, not just on the Suunto but on all) but is bigger and seems to go thru batteries faster but they are easy to change yourself.

The Freestyle was knid of goofy and not very accurate. The Nike didn't really inpress me and you have used the Timex. The Polar, which is more of a fitness tool than for navigation is way too complicated. I have had one for two months and still haven't quite figured it out.

From all I have read on GPS units as well as field experience the altitude function is less accurate. I use my altimeter and compass far more than my GPS and also like having seperate units. The ones I mentioned are super easy to calibrate and very useful with the barometric function.

Hope this helps.

Ed T

Shawn
03-24-2005, 07:00 AM
Ed T,

I've got a Magellan Meridian Platinum. IT has a barometer in it that it uses to find altitude. Which seems weird to me, I can sit and watch the altitude fluctuate casue I assume it is using the barometer to measure altitude. I would rather it use the GPS to measure altitude.

The problem with the altimiter/barometer from my perspective: One equation PV=nRT is essentially what is being measured. P=pressure V=volume n,R are constants, T=temperature. So when trying to measure the altitude, these devices use a barometer which measures the atmospheric pressure. I assume you calibrate up front before you walk, but as one goes up the mountain, temps tend to decrease, pressure decreases as well. However, barometric pressure can change as you go up the mountain as well. We've all seen fronts blow in in a short amount of time.

Unless you know your route, or happen to have a topo map handy how do you plan on recalibrating to account for all these differences? Pressure and Temperature both change independently as one goes up the mountain, my Suunto had some rather complex math to "account" for this.

Seems much more reliable to get a GPS that fixes altitude off triangulation relative to a barometric measurement.

I've had the Suunto for about a year and a half, and haven't been terribly interested in the altimeter once I looked into how they are measuring it.

Just my opinion, it is very possible that all the things I mentioned are not a big enough factors to result in poor accuracy. I just dont know.

Sawtooth
03-24-2005, 07:08 AM
Ed,

I too have the Avocet Vertec Aplin. My only complaint is that it does not have an alarm. Mine is about 6 or 7 years old. If I don't set an alarm, I will sleep right through and wake up around 7:00. So I take my pager to use as an alarm. It's also an inconvenience, having to send the unit in to Avocet for battery changing. The batteries ran out this last time, and I've been going without the Avocet, and just using my favorite watch, a Chase-Durer US Special Forces 1000 (which is WAY more durable than the Avocet). I stopped competing in 1997, and I no longer need to tally up feet ascended or decended, or exact duration of runs. I use my map and terrain association and if need be, my GPS for altitude. My opinion is changing on the need for one "does all" unit. I have a good watch, a good compass, a good GPS, and I have a thermometer on my survival whistle. If I break one, the others are unaffected. Just my evolving opinion and .02 worth.

Ed T
03-24-2005, 07:10 AM
Shawn,

Most all of the good altimeters are temperature compensated. In checking known elevations, both the Avocet and the Suunto were nearly always within five feet in a 2600' climb. My Garmin GPS varies considerably more than this.

You do need to calibrate fairly often, especially if a storm is moving in. I always have a topo with me if in unfamiler terrain, so that not a problem. Everybody is different, but I would never trade my altimeter, map and compass for a GPS if I had to choose.

Perhaps Dick Blust could give us some insight on this.

Ed T

Ed T
03-24-2005, 07:16 AM
Shawn,

Here is an interesting discussion on GPS vs altimeters. Deals mostly with flying but the principals are the same.

http://docs.controlvision.com/pages/gps_altimetry.php

Ed T

Sawtooth
03-24-2005, 07:17 AM
I can hear some of you now..."he takes his PAGER out with him for an alarm"! Well, with a pregnant wife, it's a comfort to her knowing she can reach me in an emergency. Sure is lighter than a cell phone (which doesn't work around here), and you can set it for vibrate so you don't have the noise.

Stan
03-24-2005, 07:22 AM
Ed and Shawn, I gotta run - be back in 3 days or so. I'll grab a book and check while I travel, but, Shawn, doesn't a GPS triangulate purely from sat. positions and not relative to a barometric measurement? From a fixed point like a camp, monitoring a bar. alt. can be useful to predict upcoming storms. Relative elevation differences with a bar. alt in stable weather tend to be more accurate than with a GPS, in my experience.

Stan

Smackdaddyj
03-24-2005, 07:22 AM
Sundles--

I agree with you on altitude, but I am not a big mountain climber, and I have heard that it is more important to know how fast you are climbing if you are making a rapid ascent. However, the GPS is a nice function if you trust it. You just travel for the day and when you are ready to return home, you turn on the GPS and follow the arrow. I have used it truck hunting, but I prefer to use a compass and map for long hiking. I still take the GPS, but it is seldomly used. Just my thoughts on them.

Smackdaddyj

Ed T
03-24-2005, 07:41 AM
One more link that states 100 meters + or - is the standard. Not close enough for me. Isn't that why many GPS units come with barometric altimeters built in?

http://www.exploroz.com/Forum/Archive/2005_1/19160.asp

anthracitic
03-24-2005, 07:58 AM
GPS Altitude Readout > How Accurate? (rev. 2/10/01)
New GPS buyers are frequently concerned about the accuracy (or lack of it) of the altitude readout on their newly purchased GPS. Many suspect their equipment may even be defective when they see the altitude readout at a fixed point vary by many hundreds of feet. This is NORMAL.

With most low cost GPS receivers, the horizontal error (without SA now that it is off) is specified to be within about +/- 15 meters (50 feet) 95% of the time. Most users find this is a conservative specification and that their modern GPS receivers routinely perform better than this worst case specification. But.. Users should expect that SOMETIMES they may see the error approach the specification limits. AND.. 5% of the time, the error may be "any value" from zero to whatever". Note: Unless you have a CLEAR AND UNOBSTRUCTED view of the sky (on your dash or looking out of an airplane window with no externally mounted antenna, or similar obstructed view does not count!) you can count on your error excursions to be much greater than the above numbers. Your GPS <depends> on this clear and unobstructed view or it cannot make accurate range measurements to the satellites.

Generally, Altitude error is specified to be 1.5 x Horizontal error specification. This means that the user of standard consumer GPS receivers should consider +/-23meters (75ft) with a DOP of 1 for 95% confidence. Altitude error is always considerably worse than the horizontal (position error). Much of this is a matter of geometry. If we (simplistically) consider just four satellites, the "optimum" configuration for best overall accuracy is having the four SVs at 40 to 55 degrees above the horizon and one (for instance) in each general direction N, E, W, and S. (Note: You will get a very BAD DOP if the SVs are at the exact same elevation. Luckily, this is a rare occurrence.) See: DOP demonstration site by Norris Weimer> How SV geometry affects GPS accuracy(Java Required).. The similar "best" arrangement for vertical position is with one SV overhead and the others at the horizon and 120 degrees in azimuth apart. Obviously, this arrangement is very poor from a signal standpoint. As a result, of this geometry the calculated solution for altitude is not as accurate as it is for horizontal position. Almost any calibrated altimeter will be more stable at reading altitude than a GPS.

GPS altitude measures the users' distance from the center of the SVs orbits. These measurements are referenced to geodetic altitude or ellipsoidal altitude in some GPS equipment. Garmin and most equipment manufacturers utilize a mathematical model in the GPS software which roughly approximates the geodetic model of the earth and reference altitude to this model. As with any model, there will be errors as the earth is not a simple mathematical shape to represent. What this means is that if you are walking on the seashore, and see your altitude as -15 meters, you should not be concerned. First, the geodetic model of the earth can have much more than this amount of error at any specific point and Second, you have the GPS error itself to add in. As a result of this combined error, I am not surprised to be at the seashore and see -40 meter errors in some spots.

DGPS operation (where available) will dramatically improve the performance of even low cost GPS receivers. Horizontal accuracy of +/- 5 meters and altitude accuracy of +/- 10 meters (relative to the WGS-84 geode) with suitable DGPS receivers and low cost GPS receivers such as the Garmin GPS-12XL can be expected.

In any case, it is extremely unwise to overly depend on the altitude readout of a GPS. Those who use GPS altitude to aid in landing their small plane should have their insurance policies paid up at all times.

Joe Mehaffey

Ralph
03-24-2005, 08:14 AM
All barometric altimeters will change as the atmospheric pressure changes, nothing can be done about that. The weather gives you a pretty good clue about whether you will read high or low.

For wrist compass I use a Suunto wrist sighting compass with a rotating bezel to quickly check bearing. Weighs nothing and is simple and reliable.

I got a small, inexpensive GPS last year to play with. Most of my time is spent canoeing, so the way I use it is to mark a few waypoints like my truck, maybe a town or dwelling nearby and then forget about it.

In a canoe, direction doesn't mean much, upstream &amp; downstream do. My theory is that in the highly unlikely event something happens to my canoe, I can head out to my truck in a beeline rather than following the stream back. Winding down a stream, it's easy to lose track of relative position. The GPS resolves this problem.

Ed T
03-24-2005, 11:00 AM
Sawtooth,

I forgot the old Vertech's didn't have an alarm. The latest one I have does and I agree it's a useful feature. At one time their customer service really sucked at battery replacement, something like three weeks. I've heard it's better now.

I know what you mean as far as the need to have all this data. Thats probably why I am having such a time figuring out the new Polar. I don't really care how far Iv'e run or hiked, nor at what speed or what my heart rate is. I leave when I leave, get back when I get back, and have been doing this long enough to know when I am slacking or pushing my self too hard. I don't know if that means I am stepping into geezerhood or what.

Ed T

Shawn
03-25-2005, 12:19 PM
Stan,

I assumed the same thing, but my altitude tends to float on my GPS. Altitude is really not a huge concern to me. I typically know the area I hunt pretty well, even though it is huge. It is very handy though, helps me get back to my truck/tipi in the dark pretty easy. I gotta carry batteries, but that is what my malinois is for.
Now that I'm much more confident in my rambling, I rarely carry it with me now adayws, except to see how far I walked, or to mark interesting points on the ramble.

Sundles
03-25-2005, 12:32 PM
Ha, while you guys are busy messing with electronice in the wilderness. I'll be enjoying the wilderness with out so much as a wrist watch on. I go out there to get away from all that stuff. Part of the skill involved in wilderness travel is to be capable of finding your way around. Yep, I've been turned around several times in my life, but I got it figured out with out using any thing but my eyes and my brain.

DJ
03-25-2005, 01:43 PM
I guess all the various bells and whistles are a matter of personal preference, but I can certainly attest to the durability of the Suunto. I've worn mine nearly every day for the last 5 years (on my third battery now). You can barely read the cardinal directions on the rim these days, but it's kept on a-tickin'. I tend to follow contours as much or more than game trails when heading out before light in the morning, so the altimeter function is pretty handy for straightening out those wiggles around trees and scree on the way to the honey holes.

Dick Blust
03-25-2005, 02:31 PM
I'm afraid I'm not in a position to offer much insight into altimeters, as I simply don't use them. If you're using map, compass, and GPS in concert and thus are able to accurately plot your position, having an instrument that provides altitude simply becomes superfluous - at least for me - unless, of course, you have a need to know your altitude very specifically. As has been pointed out elsewhere in this thread, the altitude a GPS provides is often going to be quite inaccurate, as even the manufacturers admit. As far as wrist compasses go, I'm all for them as backups, but much prefer a compass capable of taking good sightings.

I've received a number of emails, etc., concerning when the rest of my Back Country Navigation for the Hunter essay; Maggie assures me the next installment, Compass and Position Plotting, will be up soon.

Dick

Ralph
03-25-2005, 04:19 PM
One of the nice things about the Suunto is that it has sights and a window allowing direct reading while sighting. However, I agree with Dick, I also prefer one with a good sighting plane and the wrist model is better as a backup and a quick reference. If you use these, be sure to get one with a rotating bezel that takes some effort to turn.

The little button compasses are really for emergencies only, when space is really a premium. The smaller Silva types are so light and compact there is really no reason not to use those as your backup.

Stan
03-26-2005, 07:00 PM
Thanks to all for the info.

Ed, I'm with you on going with a altimeter, compass and map first (and I use a GPS almost daily) - they've saved my bacon too many times and don't require batteries.

DJ, Sounds like you're sold on the Suunto - does it measure altitude and a bearing continuously or are they timed readings? That really bugs me with the Timex.

I'm surprised by the little interest in bar. altimeters on the board. It may be a need, needed by few, but where there is heavy tree cover and hence poor GPS coverage, a bar. altimeter can greatly assist in locating yourself on a map, especially on some featureless thickly timbered slope or ridge. These are often so thick that you cannot see out suffciently to visually get a reference to another mountain or geographic feature. Back in the bad old days before GPS, an altimeter was requireed equipment for anybody doing any sort of mapping in any areas of sufficient topo. relief. Yep, Tim, maybe not always needed for hunting or wilderness traveling, but I'm too used to using these for work to not have them around. If I ever go hunting with you, I promise to keep them hidden!

cutty
03-26-2005, 09:28 PM
Sundles, there are two things that I have found a gps unit indesensible for.
1. You kill something, a bull elk. I f you have to go back for more than one trip, it is far better than hanging ugly orange tape all over the woods.
2. Used in conjunction with Nat. Geographic topos on my computer, I can plot a course within ten feet of 15 or 20 spots I want to hit while scouting, put them in my gps and go. I could do it with a map too, but ti takes alot more time isn't near as accurate. Plus, If you are scouting or hunting and run across an incredible little spot that wasn't seen on the map, you mark it and go home. You can see exactly where it is in relation to everything.
3. Sure, you can figure it out with your eyes and brains, so can i, and did so for years. But now I can just hike and scout for miles, marking cool spots the whole way, then turnaround and walk eight miles right to my truck.

A gps doesn't lower my ability to enjoy the wilderness, it heightens it. Allowing me to go and go with no worries. I did the instictive compass thing, and the map and compass thing for years, and can still, but I would not trade them now for my GPS. MY opinion. Dan

DJ
03-27-2005, 05:33 AM
Stan, as I mentioned, mine is several years old so I'm sure things are "new and improved" since my purchase. But, yes, both are continuous. I still use a Garmin Venture to mark waypoints and for recording notes, but the advantage of the wrist computer is that it uses less juice than a GPS on continuous operation. And, it just takes a quick glance whereas I inevitably fart around with the GPS longer. That said, I'm unfamiliar with the new wrist GPS units like the one Suunto (http://www.rei.com/online/store/ProductDisplay?storeId=8000&amp;catalogId=40000008000&amp; productId=47818159&amp;parent_category_rn=4500600&amp;) makes. I imagine we'll have it all lumped into a single unit at a relatively better price in a couple of years. $700 is more than I want to spend right now when I know the price will be dropping.

elmbow
03-27-2005, 03:07 PM
Cutty, I agree with you on how a GPS can add to one's outdoor experiences. I was using them back in the late 80's when the Army was first fielding them and they were a joke amongst cavalry scouts and infantry recon folks. You could almost count on them giving wrong readings. I've never forgotten that lesson and will never venture forth without map and compass. But they're great for plotting courses in anticipation of a trip, for marking hidey hole wallows in the timber, poached animals, Piute metates or any of a gillion other things that you may want to precisely locate and simply can't do with a map. A few years back I was traipsing through a basin about 10k ft and found a beautifully preserved Indian drill (looks like a spearhead about 3" long) together with some other remnants of flint knapping. Apparently I had stumbled across a Ute summertime camping location. With the aid of my GPS I was able to pinpoint the location and bring an archeologist back to the site. In order to locate yourself precisely with a map and compass you need to triangulate your posiiton and that requires visibility and landmarks both of which aren't to be found in deep timber, featureless deserts or storm clouds above timberline. Another advantage to them is the speed they let you cover terrain with, particularly if you have to travel at night. In the three years I've owned my GPS, I've found it has helped me improve my map and compass skills, not diminished them. I hope never to become a slave to technology but I will cetainly use it to my advantage when appropriate.
I also noticed on this post that no one has mentioned the advantage that an altimeter offers when combined with a topo map with its elevations and contour lines. By using your altimeter you can follow contour lines thereby avoiding unneccessary ups and downs enroute to your chosen location. You can even get to your chosen location without a compass by doing the same.