Some users experience emidiate crash after startup, after updating to version 3.xx.x from a 2.xx version.
This seems to be caused by a saved app state from the previous version, that lead to a crash, or maybe it's caused by this issue.
The workaround is to remove iRegatta from the device (long tap on the iRegatta icon and then press the X in the upper left corner), and reinstall it from the App Store. Don't worry - the App store won't charge you again.
Unfortunately this will also delete your data (waypoints, routes, polars), so I hope you have a decent backup of these.
Sorry for the inconvinience.