Max dynamics without goggles

[watts]

If its only one swim per session your eyes should be fine. I Pop the goggles on after my main swim for drills and the like.
I did once get to a pool at 530 am before everyone and did a dynamic to find out later that the whole self dosing unit of the pool had dumped the entire contents which burned my eyes and skin. Couldn't see properly for 2 days. :crutch

 

[watts]

Remember most HR monitors are often shit for low numbers.
Sebastien Murat suggested data loggers are better but need to be downloaded to see results.