Was I dumb to buy a 310xt?

I was in the same situation and I pulled the trigger on the 910xt (haven't received it).  TRIVILLAGE has 15% off if you spend over $200.  They give you the coupon code the minute you add something to your cart. 

What I do know about 310 and 910 is that swimming accuracy is not good unless you put the watch in your swim cap so it has clear view of the sky.  However, I've heard others say they get very good readings with it on their wrist. 

on your next swim, put it in your cap and see how the reading compares.  Also check for any software updates. 

Make sure you have the swim mode enabled. Also, the current software version is 4.20. Access your current version by pressing the mode button, selecting "settings", and then select "about Forerunner". If you're not updated, go to the Garmin website and put "310XT software" into the search box.

I've had mine for 2 years and it's been bulletproof. I think it does a pretty decent job of measuring distance in the swim mode, it's just the track line that will look sketchy. If you put the watch in your cap when you swim, you'll find the track line will straighten out somewhat. I don't do that because it's just not that important to me.

Check out:  http://www.dcrainmaker.com/2009/09/garmin-forerunner-310xt-in-depth... There is a ton of user information there. Good luck with it!

Spot on! Using my recently purchased "pre-owned" 310XT for my first 1/2 Iron distance race a few weeks ago, on my wrist, the 1.2 mile open water swim registered at 1.34 miles on my watch....the swim times tell me that the course may have been a bit long. (my swim sucked, but it looked like it could have been a touch long.) An Olympic distance race in April showed the distance nearly spot on.

Be sure to have the "Swim Mode" enabled! However, the GPS accuracy is horrible in a pool, so I turn the GPS off and just hit the lap button after every 100.

You made a good purchase, don't sweat it!

You don't even have to put it in a bag...just slip it under your cap. Also, while the track line will more than likely not be straight, it will be straighter than if just worn on the list. The disparity in distance between the advertised course distance and the distance shown on your watch could be caused by either the course distance being inaccurate or you not swimming a good line and therefore swimming a greater distance than advertised. There is a discussion of this over on DC Rainmaker.

Because we mostly have an inherent inability to swim in a straight line and we desire to see how our pace compares to other events of similar length. If we don't need GPS for the swim, then why do we need it for the bike and run.

Thanks for the tip! Just ordered my 910 off Trivillage and got that discount too

Well if I know the course I don't need the GPS but often bike and run different courses.

Thanks!!  Just tried to buy one at Road Runner with a coupon, they said in store it does not apply to electronics (doesn't say that anywhere... ) but with the 15% and no sales tax (or shipping), cheaper at trvillage!  

I have the 910XT and it is great. I have had times when it recorded more laps (indoor) than I swam or it grabbed a swim stroke different than I did and this was always when one of two things happened: I forgot to pause it if I paused for a breather OR there were people swimming close by (sharing a lane). Outdoors it works fine as long as you set it to Open Water Swim and let it find the satelite beofre you start swimming. There is no need to paause outdoors if you have the Auto Resume set on the watch.

This has been a great tool for me to track my efficiency and strokes. Good luck!

I just read this thread, as I was talking to a friend who wants to do tris and is looking to get a new Garmin. 

So, I have a dumb question (I don't have either the 310 or the 910):  If you put it into Swim Mode for the swim on a tri, do you need to then scroll through options and put it back into (Some Other) Mode while running through transition to get on the bike (provided you intend to use it on the bike, which I would think you would)??

It seems like it would waste a whole lot of time. 

BTW...I'd be afraid I'd forget the Garmin was under my cap and either (1) drop it and loose it when I removed my cap upon exiting the water, or (2) rip my hair out with the strap fastener.  Probably both. 

The 910XT has a multisport option that allows you to automatically transition (and you can even include your transitions) from sport to sport, you just set up what sport is first, second third (transitions in the middle, etc.).

I always for get to start mine, so I have yet to use mine on a race. Maybe someone who has used on a race has feedback.