Pool swim record every 10 lengths as a lap

Hi,

I regularly swim 64 lengths in the pool. I'd like to see which parts I am going quicker and slower. How can you set the forerunner 745 to record your time / pace for every 10 laps. I've set an alert but this just vibrates every 10 lengths. I really want to see my splits for the swim. has anyone got any ideas? Thanks