"HARD WATER" in Texas...oh well, realize imanual states there should be a minimum 3ft from bottom of Spark/the intake grate - of water required to run it safely, ...so I use 4ft~ which is about the "water line" of the boat. and under 5ft, I idle speedish only. Less than, shut her down, jump in and tow with the mooring line.
Try to stay uaway from just churned water, other "wakes" in shallow depths etc.,
I've has no problem in just 5 hours with my machine but, a co rider was in 30+ feet of almost clean river water/center channel and got a bark chip, size of a quarter in his and lost his ring completely. I gotta believe it's a weak spot.