Interesting question, one I've struggled with.  I identified several problems.  First, like you mention, the Garmin battery doesn't last all day and it is too big for the swim in my opinion (I'm actually using a Timex Global trainer these days, same thing essentially).  I have raced without a watch for the swim, but near the end of the day I never know exactly where I am in terms of total time.

Here it my solution.  I wear my normal Timex HR monitor/watch on my right wrist.  I wear it all day.  I hit the start button at the beginning of the swim and let it go without touching it for the rest of the day.  I can get a pretty good swim split from the watch in T1.  In T1, I put on my Global Trainer on my left wrist in the "off" position.  For me, my on board bike computer tells me everything I need to know while riding (time, power, HR, cadence).  With about one hour to go on the bike, I turn on the Global Trainer so it can synch up with the satellites.  As I leave T2, I start the Global Trainer and use that for the run (HR, splits, etc.)  Total time can be checked on my right wrist on my Timex watch.  Yes, I am "that guy" with a watch on each wrist.  Having the total time really helped me achieve my goal at the last Ironman I did.

You should be able to synch you HR strap to both units.  I have a Cycleops HR strap that I have synched to my Timex watch and my Timex Global trainer.

Whats wrong with a Garmin 310xt or 910xt?

The 310 has a 20 hour battery life and can record all 5 phases in auto sport mode with a push of the button. I think I would put it under my swim cap while swimming, then my wrist during T1.

Whats wrong with a Garmin 310xt or 910xt?

 

The 310 has a 20 hour battery life and can record all 5 phases in auto sport mode with a push of the button. I think I would put it under my swim cap while swimming, then my wrist during T1.

 I used a 310xt in my last 2 Ironman races (Louisville and Cozumel) no problems Cozumel was my slowest, I went 13:53:50 and had battery left.. And of course swimming with the 310xt is not a problem either.

Great.  So, before I assume anything... when you used your 310xt, did you swim with it in the race and wear the HR monitor?

 

Or, did you keep it in transition?

 

Regardless, thanks for the information.
Time to shop soon.

Brian

I know this wasn't meant for me, but the 310xt is made to wear in the water. Most guys wear the HR strap under their tri top and wetsuit. Some people I know put the 310xt under their swimcap so it can get the GPS signal while swimming, otherwise the reception is poor.

The new 910xt has swim metrics built in and an open water swim setting to track the swim as well as a pool setting for laps.

I own a 310xt as of Black Friday deal and so far I'm really liking it. I went and replaced the orignal strap with a cheap velcro strap I bought at Wal-Mart. I've read that some people have had problems with a strap pin popping out while racing and the watch ends up on the ground or worse, at the bottom of the lake. With the velcro strap, it would take both pins popping out to actually lose it.

Sorry to hear your 305 quit on you. I've had mine for almost 5 years now and it has served me very well. It did start acting up last fall and shutting off in the middle of workouts. I took it apart and realized the battery was losing contact...nothing a little super glue couldn't fix! It's working great now!

Basically, what do people do when racing an Ironman?  Any advice to help a novice like me?

I didn't use anything for the swim, just glanced at the official clock when I exited the water. I did wear my HR strap under my tri suit to avoid having to put it on in T1.

For the bike, I used my Garmin 305 (already attached to my handlebars). If you're concerned about battery life, be sure and adjust the recording settings to "Smart Recording" instead of "Every Second". This will help extend the battery life. Also, your GPS files won't be ridiculously large.

For the run, I borrowed my dad's Garmin 310XT. Of course, if you borrow something try to get some time with it in training. Never race with something you haven't trained with first.

All that said, as T-Bone mentioned, w/o wearing the same watch the duration of the race, you don't know what your total time is at all times. I finished in 12:00:59 and missed my 12hr goal by :59 seconds. By my watch I knew I was close to 12 hours, but didn't have the EXACT time and didn't know until I could see the finish chute that I wasn't going to be sub 12hr. I can think of a ton of places I could have made up 1min and gone sub 12hr if I knew my overall time.