Last point is excellent. However, a good coach can be effective alone. But in some circumstances unable to actually help. It is the "stretching" in those conditions, that can lead to calamities.
I presume that prop guards dramatically reduce the chance of fatality. However it's worth examining what could still happen. For instance an arm or hand may go into a simple guard type and asphyxiation may still occur if a strap is pulled in and round tightly. It's still possible that you would...
Having been a sailing instructor, as well as being a naval architect, I will support the thesis that prop guards are a good idea. Most of the time, you are not going fast as a coach. "Bollard Pull" conditions are more common--manoevering at zero or low speed. At low speeds and especially at low...
I ran a coach boat with a 70 HP Johnson, at age 21. I had a 17 year old high school assistant running some of the time. This was before the invention of boating safety certificates but I had the USYRU coaching training for a head instructor. My assistant did not. As I remember it, I taught her...