How do you set up your hr zones for swimming?

In the GC app you can set sport specific HR. It is under the 945 settings and then user settings and Heart rate zones...

Normally the max HR for swimming is 10 bpm lower than for running/cycling (do a test to see what you can acheive). I use the same zone settings as for cycling.

Add: this swimming page suggest taking 10-15 bpm off your normal max HR: http://www.totalimmersion.net/blog/heart-rate-monitoring-for-swimming/ 

I don’t want you to think something is wrong with you if you do a swim session and a run session at the same heart rate and they feel totally opposite in intensity. If you plan on using a heart rate monitor take an additional 10 to 15 heart beats off your calculations for each zone and that will compensate for the horizontal position.

And this research suggest 12 bpm: https://www.ncbi.nlm.nih.gov/pubmed/1889941

Really interesting. I´ve never thought about that. I´m going to change my settings right away. Thanks!

Pow, thats very interesting, i only train Duathlon like and 2month ago i tried swimming to test the new OHR function on FR945 and for my feeling, my hr is higer during swim as for running.

i can't swim like a triathlet, only breastrokes totally simple and slow, could it be, that the OHR measurement don't works for me during swimming?

more or less i swam most the time in Z4, but i was slow as a don't know what ;-)

if i set my max HR -10 then i will be in Z5 only

Swimming is very much a technique sport. If not using "correct" technique RPE would feel high even though you swim slow. Perhaps Garmin OHR is not perfect for breaststroke. I have been using both the HRM Tri belt and 945 OHR and for me at least the OHR seems adequate. But I mostly do crawl and drill sessions. My technique is probably ok for a (former) triathlete (done several Ironmans and other triathlons and OW swims) as my Half IM swim is usually between 30-32 minutes. Now my focus is ultra trail running.