As far as I can this is a fairly popular sailing watch, if looking at what is on the wrists of sailors at a number of sailing clubs around the East Coast of Australia,  this a great watch for the club racer with plenty of options at a reasonable price, however this occasionally go awry with the Ronstan Clear Start Watch Resetting itself, especially when the light button is pressed.

Not mentioned in the instructions is what happens when the battery of the Ronstan Clear Start watch gets a bit flat, is that when you press the set button the watch momentarily displays every character on the dial then resets itself to 12:00.  Seems that if the light function is turned on (Set turns the back light on)  and the set button is pressed it turns on the backlight, which draws a lot of power.  Drawing more power from the weak battery causes the voltage to drop to a point where the watch resets.

The watch was also behaving strangely when the clear button was pressed, I normally reset the time before every race and pressing the clear button enters the appropriate mode, every digit and icon on the display would turn on when clear was pressed and it just sat there sulking eventually resetting itself.

A fresh battery fitted and all is good again.

Thanks to a contributor to Sailing Anarchy who goes by the name XYZZY who posted this information long before I knew there was a problem!