After all this talk about engine pressure and counter measures...I decided to tighten my loose alternator belts and clean out my Hardin thermostat housing since I haven't opened it in a while and I boat in a crap filled river. I noticed a broken hose clamp laying under the balancer.
This probably happened the last time I was out. The hose had not blown off. I had made a 10 mile full throttle run to the ramp. Never seen this before. Check those clamps!
Not sure of the brand. Look on EBay for 5/8" blue silicone heater hose. The first five or so look to be the same as mine. I bought it in 2012 and it still looks new. I paid $75 for 25' including the shipping. It is much easier to install and remove. It doesn't get hard and crack, and it looks cool. It's also very easy to clean. Never had it slip off a fitting, even when I pissed-off the Spirit of Pascal!