As noted...
Many manufacturers actually recommend reverse.Someone, with far more apparent knowledge of physics and hydrodynamics, made a very cogent argument that a stopped propeller generated less drag than a turning one. I, personally, found his arguments very convincing.Lastly, when my tranny is left in neutral or forward, it makes a very unpleasant noise. Years, and years, of behavioral modification have left me with an irrepressible association between bad noises and bad things happening and an irresistible compulsion to stop such noises. Hence my tranny seems to inevitably find its way into reverse.At some 16,000+ pounds of displacement, starting a diesel inadvertently in gear gives me little concern...it takes a while for the prop to have any effect on her motion. Decades of water skiing makes me instinctively check the water around the boat before ever starting the engine.