910xt and swimming

William Jenks

For reasons not worth going into, I recently purchased a new Garmin 910xt and I am very happy with it.

There are a couple of swim related things I am curious about, though.

1) Has anyone figured out what triggers its decision that you have completed a lap?  Obviously, over the course of 200 or more, the total time is fine, but I am pretty sure that there are pretty bad irregularities length to laplength(where one lap gets a chunk of time that was really in another lap before or after) , and I can't figure out what exactly trips the length turnover (pushoff? reversal of arm direction??...what part of your swim stroke?)

2) More out of curiosity than anything else... when I'm doing fast work, the auto-designated stroke that turns up is often wrong. Today I apparently did a series of 25s randomly distributing free, back, and fly.  The truth is this doesn't matter at all, but has anyone else experienced the same thing?  It's almost never wrong for less than sprint work, which tells me it has something to do with the stroke quality/length, but again i don't know what.  I'm no great swimmer, but no one would look at my sprint and say it looks ridiculous compared to my normal strokes.

Thanks, Wm

Joseph Lombardi

Posted By William Jenks on 05 Sep 2012 04:28 PM

For reasons not worth going into, I recently purchased a new Garmin 910xt and I am very happy with it.

There are a couple of swim related things I am curious about, though.

1) Has anyone figured out what triggers its decision that you have completed a lap?  Obviously, over the course of 200 or more, the total time is fine, but I am pretty sure that there are pretty bad irregularities length to laplength(where one lap gets a chunk of time that was really in another lap before or after) , and I can't figure out what exactly trips the length turnover (pushoff? reversal of arm direction??...what part of your swim stroke?)

2) More out of curiosity than anything else... when I'm doing fast work, the auto-designated stroke that turns up is often wrong. Today I apparently did a series of 25s randomly distributing free, back, and fly.  The truth is this doesn't matter at all, but has anyone else experienced the same thing?  It's almost never wrong for less than sprint work, which tells me it has something to do with the stroke quality/length, but again i don't know what.  I'm no great swimmer, but no one would look at my sprint and say it looks ridiculous compared to my normal strokes.

Thanks, Wm

 

Bill - I have the 910xt and love it...it is GPS triggered....so there is no real recognition of "lap" you are basically swimming continuous tight cirlce...and it is not very accurrate on the distance in a pool/lap setting (are you wearing it in your cap? you really can't wear it on your arm due to the water immersion gps signal loss issue)....to contrast I just purchased the Garmin Swim which is Accelerometer based (no gps)..and it registers lap by change in direction when you push off from the wall (and distance is caculated by entering the pool size) it counts laps great..........

 

if you haven't already...check out the full DC Rainmaker discussion/review of swimming with the 305/310xt...it will answer all your questions.  (www.dcrainmaker.com).

www.dcrainmaker.com/2010/06/new-gar...water.html

GMAN 19030

Joseph,
The 910 is accelerometer based for pool swimming. It's triggered by a change in direction just like the Garmin Swim. They're nearly identical when it comes to pool swimming. You're mixing up devices here. William asked about the 910 not the 310.

William,
1. Make sure the setting for the pool size is correct (25y or 25m or 50m).
2. Make sure to do a quick and complete turnaround and push of from the wall before taking a stroke to be sure the accelerometer realizes you changed directions and sped up in that new direction.
3. Update to the new firmware that came out last week. It addresses laps not being recognized as quickly as they are with the Garmin Swim.

Joseph Lombardi

 Oops my mistake...I was thinking about the 310xt....

William Jenks

Yes, you're right Bob... accelerometer based. I was just trying to figure out what the "trip" is for the length to be called over.

I am still trying to figure out how to navigate GC to get to any firmware updates, but I presume I'll find that. :-) Thanks for the tip.

Joseph Lombardi

 The trip...is change of direction...for accelerometer based units...(I have the Garmin Swim...which is basically a swim only version, accelerometer based)...key variable are settting the right pool size and a good push off from the wall....I can't comment on swim stroke detection...I will look at the Garmin Swim documents and see what they say..

 

According to Garmin Swim FAQ's: What can cause distance errors when Pool Swimming?

 

The Forerunner 910XT and Garmin Swim require a consistent stroke pattern, which is seen in swimmers with lap swimming experience.

 If new to lap swimming, the Garmin swim watches may not accurately record swim data. As swimming technique improves, the accuracy of the swim data will improve. 

Striving for a strong push-off the wall with a long streamlining (glide) phase will also help the watch accurately count lengths.

 

Other inaccuracies can occur if Lap (910XT) or Pause (Garmin Swim) is not pressed during rest periods. When stopping to rest, press Lap or Pause. When ready to resume swimming, press the button again. This will create rest and swim intervals in your data.

 

The following actions can cause inaccurate distance:

 

Switching stroke mid-length

Stopping or walking mid-length

Dramatically changing speeds mid-length

 

Drills affecting the arm motion (including kick sets, one-arm swimming, catch-up crawls, sculling, dog paddle, etc.) will not be measured correctly, if at all. For the Garmin Swim, the watch should be left in pause mode for drills or drill logging can be used.

 

AND For STROKE TYPE:

The Forerunner 910XT is able to detect four different swimming strokes. The below list shows each stroke type and the term used in the data field:

 

Freestyle - Free

Backstroke - Back

Breaststroke - Breast

Butterfly - Fly

If a swim interval contains lengths with different stroke types, the Forerunner will display Mixed. If a combination of strokes is used in a single length, the Forerunner will assign one of the above stroke types instead of Mixed. Mixed is used for an interval made up of lengths where a different stroke type is used for each length.

 

The Stroke Type data field can only be utilized with the Forerunner 910XT set to Pool Swim within the Swimming sport mode.

 

mancona

I've definitely found that when I do a good flip turn and streamline my 910XT is very accurate and every lap time is consistent, but towards the end of swims if I start to get lazy and tired and do slow sloppy flips and start swimming right off the wall occasionally the individual lap data isn't quite perfect.

William Jenks

I don't think the data are grossly wrong, but there's no doubt that the trigger has to be during or after your turn. So the data for lengths in the middle of an interval should be self consistent if it's picking up on the same point each time. However, the first and last should be off a little. My turns will not win any style points and I am wondering if it's picking up at different points in my turn. That's all.

That said, I did download the new firm wear now and I'll be curious to see if that cleans up my length to length variation.

Stephanie Stevens

I have never learned to flip turn well, but have found the 910XT to be very accurate in counting laps with my "touch and go" at the walls.

I have more trouble with open water swims. It seems like my watch alerts with the "Lost satellite signal" warning a lot.....like 2-3 times per hour when I am swimming. I think I swim pretty steady in the open water, although I know I don't swim especially well.

[Deleted User]

I agree with what Bill is saying. For me it is very accurate for distance and number of laps (since you tell it how long each lap is, no surprise), but if you swim 100 yds for example, the times for each 25 yrd segment do not seem right - some too long, some too short.

Also, to update the firmware, go to Garmin Connect, and look for the small black box in the upper left labeled Garmin.com and click on it. A menu will open at the top - click on My Garmin. Here you will have to sign into your Garmin account, and another page will open. Then click on my Dashboard and you should see if updates are available. Unfortunately there seems to be a bug, and it always says that there are updates available, even if they are not. I currently have version 2.6 firmware.

There might be an easier way to get to the update page, but I have not found it yet.

GMAN 19030

Posted By Stephanie Stevens on 06 Sep 2012 05:59 PM

I have never learned to flip turn well, but have found the 910XT to be very accurate in counting laps with my "touch and go" at the walls.



I have more trouble with open water swims. It seems like my watch alerts with the "Lost satellite signal" warning a lot.....like 2-3 times per hour when I am swimming. I think I swim pretty steady in the open water, although I know I don't swim especially well.

Stephanie,

The lost signal has nothing to do with how well you swim.  It's because the watch continually goes underwater and simply loses the signal.  It happens to everyone.

MattAaronson

I've had very few errors with either stroke or lap triggering using the 910xt. The only incorrect stroke detection was when I did some backstroke for the first time ever and I guess the form was so bad that it thought I was doing something else...yikes!! I do share William's curiousity as to learning precisely how the accelerometer data is interpreted to trigger a new lap. From the above FAQs it seems some break in the stroke frequency is part of the magic.