GPS Watches

RE: GPS Watches

Former Member — Sat, 22 Oct 2011 16:07:58 GMT

I know that all GPS watches are not that accurate in water, but still it it better than nothing. You complained about the size of the Garmin 310XT - well I think you should look at the battery aspect. The battery of the Garmin 310XT works for up to 20 hours workout. I personally like the grey orange style. I read a nice review about the Garmin Forerunner 310XT. I definitely also want to check out the latest Garmin models. It all boils down to how much you want to spend. I just love the Garmin watches - so that's why I would not go with a different brand.

RE: GPS Watches

Sojerz — Sat, 15 Oct 2011 11:28:40 GMT

My engineering firm uses GPS for land survey, and the accuracy of the location depends on the quality of the GPS equipment and the number and quality of the satellite positions. The USAF lifted their public restrictions on accuracy many years ago and you can now survey locations using GPS to within hundreths of a foot with survey accurate equipment and network RTK GPS that adjusts the data location without post-processing. If you don't have network RTK GPS then you have to post process the data to correct for satellite signal varriations. That said, the GPS equipment in watches is probably only accurate to about one to five meters when satellite condions are best, and falls off from their if you aren't getting good satellite reception. Because you don't post-process the data, there is no way to make corrrections for satellite variations (not that you would want to given the accuracy of the this equipment. I'm guessing the watches are typically accurate to about 20 -40 meters horizontal (about the same as for a car garmin, again depending on satellite conditions). This is why when you swim laps in a pool you see a lot of fuzz and it plots some the locations in the parking lot. HOwever, it should be plenty accurate for OW swims as long as you can keep it out of the water. I've been using the swimovate pro (no GPS) in the pool and it works well, except kick and drill sets which you have to edit into the database after you upload. Most of my pool swimming in NJ is indoors so GPS won't work anyway. Probably will get a GPS watch for running and biking to try some triathlons.

RE: GPS Watches

Former Member — Thu, 13 Oct 2011 07:16:28 GMT

I use my Garmin 205 to swim in open water. I put in my bag of dry Swimsafe ISHOF is dragged behind me. The dry bag is thicker than a bathing cap. I guess I'm sure the dial is turned up, but that's all.

RE: GPS Watches

dc_in_sf — Fri, 07 Oct 2011 06:04:26 GMT

This is an in-depth review of the 910XT. It looks like it will cost about $50 more than the 310XT. It's smaller, nicer looking, and it is supposed to work in the pool, counting laps and strokes (like the Finis SwimSense or the Pool Mate). Spending $349 on the 310XT would kill a little part of my soul, but, if the 910XT works as advertised, I probably wouldn't mind parting with the $399. To get an accurate distance or to get an idea of how straight you're swimming, you still have to wear it under your cap. The lap counting features sound very cool. Pity I just bought my 310xt like two months ago :frustrated: I suspect there will be good deals on the 310XT when the 910XT starts to ship so it might still be a good option if OWS is the primary use.

RE: GPS Watches

dc_in_sf — Wed, 05 Oct 2011 12:56:04 GMT

On Amazon, it's $349 without the heart rate monitor, $399 with. FYI Garmin just released the Forerunner 910XT that allegedly has more swimming functions: sites.garmin.com/.../

RE: GPS Watches

Former Member — Wed, 05 Oct 2011 09:24:39 GMT

RE: GPS Watches

Former Member — Wed, 05 Oct 2011 05:29:41 GMT

On Amazon, it's $349 without the heart rate monitor, $399 with.

RE: GPS Watches

orca1946 — Tue, 04 Oct 2011 11:00:37 GMT

What does the 310 xt cost?

RE: GPS Watches

dc_in_sf — Mon, 03 Oct 2011 07:51:07 GMT

Despite the 310XT being ugly, it is nice to not have to worry about bagging it or other contortions to keep it dry. I took mine off the supplied strap, replaced the spring bars with some beefier ones and threaded it onto my goggle strap.

RE: GPS Watches

Former Member — Sat, 01 Oct 2011 12:46:01 GMT

Read dcrainmaker's review of the 310xt to get an idea of they type of track you should get when using it for OWS www.dcrainmaker.com/.../new-garmin-forerunner-310xt-openwater.html Yedswim, thanks for posting this link. Definitely the best technical info I've gotten on the subject. My race was cancelled, so I did another test in the pool. It turns out the problem was with the settings. I had Auto Pause and Auto Lap turned on in the previous tests. I did two tests today. Both with Auto Pause and Auto Lap turned on. In the first test, I had the Data Collection Mode set to collect data every second. I swam 750 yards of drills/drill-paced swimming. Garmin came up with 830 yards, jagged path, but pretty much in the general area where I was swimming. Then, I set the Data Collection Mode to Smart Collection. I swam 250 yards, a little faster than drill pace, open turns. Garmin came up with 264 yards, almost exactly straight. So, the magic settings are, drum roll please, Auto Pause OFF Auto Lap OFF Smart Recording ON great topic, i'd like to hear what other people are using. i've 2 forerunner 305's. ugly? got to agree with you. it is always on the back of my head, held in place by goggle straps, then everything covered with a latex cap. no baggies or other water protection. the swim distances it comes up with are the same as i get from topo maps, probably because there is unobstructed satellite reception in the middle of lakes. can't say the same about its distance-accuracy when using it for forest trails. 305's can be had at times for as low as $110 new on Amazon. Geog, how long have you had your 305? I would love, love, love to ditch the ziploc bag, but I'm afraid it might reduce the lifespan.

RE: GPS Watches

yedswim — Sat, 01 Oct 2011 12:06:56 GMT

One quick comment: My understanding is that USAF limits civilian GPSs to a maximum accuracy of 10m, is not unusual to see the GPS coordinates jumping 10-20 meters. You will get better results in a longer race. Read dcrainmaker's review of the 310xt to get an idea of they type of track you should get when using it for OWS www.dcrainmaker.com/.../new-garmin-forerunner-310xt-openwater.html (I know is not the same FR you have, but should be very similar) Good luck with your race tomorrow.

RE: GPS Watches

yedswim — Fri, 30 Sep 2011 12:09:17 GMT

Katiek: are you using GPS to keep track of your laps in a swimming pool? I don't think is going to to work well in that scenario for a few reasons: 1) Flip turn will make the GPS loose track of the satellites 2) GPS coordinates are not precise enough for a good track in the pool 3) GPS measures your position at intervals and the sudden change of direction will affect the track. To keep track of your pool workout is better to use something like the Finis Swimsense. For OWS a GPS in a cap works great, look at my track in the La Jolla Rough Water: connect.garmin.com/.../113749552

RE: GPS Watches

Former Member — Fri, 30 Sep 2011 08:38:15 GMT

Thanks everyone for your comments. antenna faces up/forward, then the latex cap over everything, listening for the beep of an inadvertent button press (never happens). i don't press the start button until i'm in the water and ready to swim. Thanks for this and for the picture. Great idea using your goggles to anchor it. I did have it facing the opposite way. Katiek: are you using GPS to keep track of your laps in a swimming pool? No. I've been taking it to the pool to see if I can get the kinks worked out before my next open water event. I did another test today, positioning it with the antenna pointing up. I didn't hit lap, just Start and Stop. I started and stopped several times and tried positioning a few different ways on my head. My results weren't any better. On Garmin Connect, it looks like I am swimming across 12 lanes, and thru the parking lot. It looks better in Google Earth, but it still has me 18 meters outside the pool and swimming in random directions. I hear it beeping quite a bit which I assume means that it's losing its signal. There is no part of my head that stays completely out of the water, so I'm not surprised it's losing its signal from time to time. But I still wouldn't expect the results to be SO erratic. I have a race tomorrow, so I'll try it again and let you know how it goes. For the race, I'm turning the beeps off, setting it to collect data every second instead of using "smart" recording. I'm also turning off "Auto Lap" and "Auto Pause" (unless you guys advise me differently). I'm usually good at this kind of thing...

RE: GPS Watches

Former Member — Thu, 29 Sep 2011 09:26:18 GMT

I use a Garmin for running but not open water swimming. I'm curious, with it being in your hat, does it ever fail, go into the wrong mode etc or does locking the bezel sort most of that out?

RE: GPS Watches

Former Member — Wed, 28 Sep 2011 13:46:01 GMT

I carry a sextant and a book of trigonometric tables down the back of my suit :)

RE: GPS Watches

evmo — Wed, 28 Sep 2011 05:10:16 GMT

Hmm. I've never had any of the issues you describe - but I've never used the lap function, and I've never used it in a pool. It's awkward to fumble with it while it's under my cap, so I just press the start/stop button once when I start and once when I stop. If I need to calculate lap times I just go into the 'Player' function in Garmin Connect (the online service, not the Training Center software) and re-create them manually. See attached screenshot of a recent swim I did in Santa Barbara. As geog said, make sure the unit is facing up, and try to position it near the top of your head.

RE: GPS Watches

jkormanik — Wed, 28 Sep 2011 05:07:48 GMT

KatieK - Your results are odd. I use my Garmin 205 to swim open water. I place it in my ISHOF Swimsafer dry bag which gets dragged along behind me. The dry bag is thicker than a swim cap. I suppose I make sure the watch face is facing upward, but that's it.

RE: GPS Watches

Former Member — Tue, 27 Sep 2011 08:13:00 GMT

I have the Garmin 205 now, but I'm not having very good luck with it so far. Here's what I've tried: I took it with me in the car. It worked exactly as I would have expected. When I exported the data into Google Earth, I could see my path from home to Trader Joe's and back. (Pretty exciting, I know) I put it in a ziploc bag under my cap for a race. It only captured the start point. (I have it set to Auto Lap on the Start Point and any time I hit Lap. In this case, I never hit Lap.) I heard it beep several times near the end, I imagine because it was loosing its signal. I've tried it under my cap in the pool three times. The results were pretty much the same each time. I hit Start when I started swimming, Lap at the opposite wall, and swam 12 slow (mostly drill) lengths, no flip turns. I heard it beep several times, always near the far wall. Garmin Training Center: It shows 6 laps (I would have expected 12), but the distribution is bizarre. Screenshot is attached. Google Earth: I only see Laps 1,2 and 6. The only path it saved is between Laps 1 and 2. Image is attached. I'd love to get this working for my race on Saturday--any advice is appreciated.

RE: GPS Watches

Former Member — Mon, 19 Sep 2011 15:51:41 GMT

Thanks! I broke down and ordered it.

RE: GPS Watches

evmo — Sun, 18 Sep 2011 06:19:37 GMT

I use a Forerunner 205, which I wear on the top of my head, inside a small ziplock baggie, under a cap. Works great; quick to lock on; super-accurate. The 205 is, I believe, exactly the same as the 305 (same dimensions & weight) except the 305 includes a HR monitor for ~$20 extra - which obviously I don't use since I don't wear it on my wrist. For an extra ~$230 you get the waterproof 310xt (the 205/305 are "water resistant"), which doesn't seem worth it unless you're using it in a tri context. Katie, I do think there's value in accurate trace lines (no zig zags). It's useful information if you're not swimming straight - whether from poor sighting, currents, or what-have-you. No "swim correction" software necessary if you wear it under the cap, though. The watch loses the GPS signal only if it goes under water.