Garmin 910 xt during swim leg

This is what I do.

I've used mine in one race.  No wetsuit, pool swim.  I just left it on my bike and then took in off and put in on my wrist in T2.  I didn't care about knowing my swim time or my overall time during the race.  I just wanted to know distance, mph and ave. mph (yeah, I know) on the bike and time and ave. pace on the run.  It just depends on what information you want during your race.

Yep.  The data you get out for an OWS just isn't accurate enough to be worth the chance it gets knocked off and goes down the tubes.  I leave mine on the bike and transfer it to my wrist for the run.

Multi-sport mode. One the entire time, I have the watch face on the inside on my wrist. In aero I just roll my wrist slightly to the outside and I can read speed and cadence.  

FWIW: never look at the speed when descending a big hill. For me, going 38 is fine but knowing I'm going 38 is scary.  It is better to upload the date and in the comfort of my office say... gee I was going 38. 

You will take on water in a wet suit, so it does not need to seal at the wrist

Old thread but same topic....

Do those of you that swim open water with a wetsuit put it in lock mode? I'm planning to use it in multi sport mode and worried about hitting the stop/lap button when getting the wetsuit off.

I've seen enough garmin faces pop off during transition prep to feel it's probably not good to wear it during a swim race, so I just have the regular strap it comes with for the entire time. I don't really check it during the bike leg (except when I'm in a safe straight line and can take that arm off the handlebars), and it's fine where it is for the run.

I never figured out how to take off my wetsuit without taking the watch off, so I just take the watch off first, hold it with my teeth, and take the suit off my arm without struggles, put the watch back on, take the rest of the suit off.

I wear it on my wrist the entire race.  Just did it this past weekend in O'side and it worked flawlessly.

I've never taken it off/out of the wristband. 

Why pay for all that techno stuff and then only use it 66% of the time? 

Wetsuit comes off just fine...maybe an extra tug over the watch to get it started, but hey, you're running to T1 anyway and I bet you have that extra 2 seconds for that extra tug.

I put mine in multisport mode and wear it for the entire race. I keep it under the wetsuit sleeve during the swim.

I do the same....never had a problem.

I've only used mine in OWS a few times and the distance is not too reliable.  I suppose it's "okay" if you are constantly swimming...but I was treading water for about a minute waiting for my GF to catch up and I lost GPS signal.  And once I lost it...I didn't get it back.  So you might want to test this for yourself if you really want the GPS data.  If your race has a wade start, just know that you might lose GPS signal while wading in the water, and it might not kick in when you start swimming. 

When the GPS was working...I found the distance to be off by about 5-10% longer when swimming to known pole markers (500 and 1000 meters) in a straight line.  I don't think I swim straight as an arrow, but 5-10% is quite a bit.

I personally don't care about GPS data, but more about total race time.  What I plan to do is use the multi-sport and use pool swim mode for the swim so GPS is not even a factor.  I will also use the factory strap instead of a quick release.  None of my swims are wetsuit legal, and I have a Garmin 500 for the bike.

No problem with buttons being accidentally pressed? I haven't used it with a wetsuit, but that's my main concern, that I wear it under and it goes insane or when I pull off the wetsuit the lap button is pressed enough times that I finish the race in T1.

I tugged for a whole minute in practice and it just does not come off :/ Perhaps I just lack the upper arm strength to wrench that suit off over it.  It ended up being faster if I just took off the watch.

This is what I'm concerned about also

There is a button lock function (mode and up buttons at once) but as above, could not get that to work in multisport

Hmm, I used it a lot last summer training for a 10K and it seemed pretty reliable re the distance

I likely need a bigger sample size...but distance is not a big deal for me with OWS anyway.  I swim to clearly marked poles in training...so as long as I have total time, I can figure out if I'm swimming faster or slower.

If you're treading water, that won't have any impact on whether or not you keep the signal. Either you're locked on to the satellites or you're not. Standing, sitting, treading, swimming, running, etc. won't matter. Nor will a wade start. If the satellites are picking up your device, your movement is being tracked.

Additionally, while not 100% reliable, your GPS is likely to be more accurate than floating buoys on a tri course regarding the distance you traveled. But there will be error. And there is quite a bit of difference between 5% error and 10% error. Let's go with 10%.

Your 10% error is likely a combination of the normal GPS error and the human error associated with the placement of the buoys. Then there is your navigation error ...

I often hear of people talking about how a certain race course was long. They'll get done with a marathon and see that they ran 26. 8 miles instead of 26.2. If it's certified, you can be well assured that the shortest measurable distance on that course is 26.2 miles. We just don't do a good job of running the tangents. Over the distance of a marathon, that can really add up. If you're running 9 minute miles and run an extra half-mile (easily done at that distance), you'll add 4.5 minutes to your marathon time. If you had a time goal in mind, that becomes significant.

Similarly, on a swim course, if you're swimming even 5 feet off course and then back to the straightest possible line time and time again, you're going to add a cumulative amount of distance to your overall distance covered.

So now you've got human error associated with the buoy placement, normal and expected GPS error, and human error associated with swimming the straightest line possible. That'll easily add up.
 

On this point, the reason I have lost GPS while treading, incluidng last weekend's deep water start at Oceanside, is because my wrist was underwater enough to lose the signal.  I just hold it out of the water a few seconds and it quickly regains it