I think it’s likely that those dive boats could benefit from a more formal navigation process.
The point I was trying to make is that if good procedures are in place than a SMS is not a reason to change.
Your post does show one advantage of codifying procedures is it causes them to be seen in a new light.
Difficult to image that the procedure wrt the roving watch would survive the act of typing out the words “roving watch to sleep in the passenger area”.