I high-vis orange bungee cords to make the computer a lot easier if I drop it, whether in the water or on land, or even on my back seat. I use 2 separate bungees, on on each side, so if one ever breaks or gets ripped off, the 2nd is not affected and is presumably still in place. The bungees can be looped to shorten the strap and make the same bungee fit a thick, padded arm for winter diving or a drysuit with just long underwear underneath in warm waters.
I can’t imagine a bungeed computer easily being dragged off by accident (when doffing gear to get in a RIB was mentioned earlier), but I wear these on my forearms, not my wrist. Losing something on your wrist would not be that hard to do.
I do use the original straps and clips on my Petrel, but that’s just because I haven’t gotten around fixing up a better solution. Those straps are a least 2 separate attachments and flexible for an exactly correct and tight fit, and the buckles are also darn big and dryglove-friendly. But bungees would be easier and high-vis would also be an improvement. I’m more careful with that computer though, so misplacing/dropping it is a bit less likely.