You can enable GPS and get Speed over Ground (SOG) and Course over Ground (COG) presented next to the timer to help you keep track of wind and speed in the seconds before and after start.
When you hear or see a race signal just press Gun! - You can adjust if it is a 5, 4 or 1 minute warning afterwards! And if it was just a loud noise from a flapping sail and not a race signal you can easily jump back to the previous timer.
Finally there is a great Sailing Watch available for the iPhone and it works great with the Apple Watch.
It is designed to work on iPhone with or without Apple Watch and a lot of people seem to be using it with iPads as well.
The app provides limited HealthKit integration and can optionally start a Sailing Workout activity during race start.