10,000 "blow-outs" = 10,000 different reasons why! Prop slung a blade, skeg broke off, angle of attack changed, hull/gearcase was raised to far out of the water, ice bag wrapped around the gearcase etc...
Blow-out in its simplest form is the prop losing it solid bite on the water through which it is moving. Water is 8X heavier than air, that is why airplane props are so much bigger than boat props. A marine prop isn't large enough (nor configured to move air anyway) to hold onto enough air to continue propelling itself forward, thus it "quits pushing" if no water is present. When this "push" is lost, ESPECIALLY on a boat like an Allison that's up on the pad and rolling 80+mph, then that sets up a whole nother set of problems... none of which are good.
When you lose juice in a Ranger/Toon/Skeeter etc running 70mph down the lake it's no big deal because the surface area of the hull that is in contact with the water is not much smaller than your dining room table. The Allison is running on the equivalent surface area of about the size of a piece of notebook paper or the cover of a regular hardback book. The keel line then drops and the MUCH LARGER surface area of that long keel line becomes a steering rudder, overpowers any grip the pad had and "around she goes". The effect is magnified by the unique fact that planing hull boats are not only propelled from the rear but also steered from the rear so any upset in that relationship yields much different results than seen on land or even in the air.
And not to muddy the water, but sometimes "WHODAHELL KNOWS?" is the only "fact" we're left with after some marine wrecks. That's what drove Eddie Hill from racing TopFuel hydros after his 5th accident I think it was. He was able to recreate and figure out what happened after every previous accident so he felt safe in "fixing whatever caused it" but he said after that last one that nearly killed him they just couldn't figure it out so he said, "TO HECK WITH THAT" and went to T/F dragsters.
With regards to my wreck in 09 I know mostly what happened, I was running to fast over 3ft whitecaps, downwind and I let out of it to quick. (Was turning a 28" cut chopper around 7100Rs) Which then caused the bow to drop at just the right moment, into a large trough between the waves, the bow and keel line then had a tremendous "grip" and around she went. The G-forces were so great that some of the gages were sucked out of the dash and ejected, and a speaker or two from under the dash went with them. The further toward the stern you went, the greater the "whip/pendulum" effect was. I don't care what ANYONE says, Lou Ferrigno himself couldn't have held onto that much force throwing you OUT! I was thrown THROUGH the passenger bucket on the way out and the wrinkle pattern of the glass of the cockpit was bruised/pressed into my left shoulder and back... THROUGH my impact vest! (HOW my collarbone or shoulder wasn't instantly snapped was beyond the doctors) The only real "can't figure out" in the whole deal was what opened my head up to the skull and what nearly tore my left ear off? There wasn't any blood found on the boat except for the cowling on the motor I believe I was told. I think some of the problem with that rig was magnified by the fact that it had ZERO lip and the motor was raised exceptionally high (for an Allison, something on the line of 1.25"-1.5" above pad). I'm not saying that's what caused it and in fact the boat ran very well like that and several have been run like that before and since. But I think that specific to the Allisons, such gearcase heights make blowout in rough water (or anyother "quick changes in angle of attack") more likely and violent simply because theirs less surface area of both the pad and the gearcase/prop itself in the water to "hold onto".
You'll spend the rest of your life wondering "What if/why". I don't push the envelope nearly as much anymore as I used to but it's not based any fears. But instead it's because what had the BIGGEST impact on me during my incident wasn't my own laying in the Neuro ICU room for a few days or even the pain I suffered during the healing. No the BIGGEST reason I don't push as much anymore is the tears and impact I saw it all had on my wife, my kids, my mother, friends, employees and ESPECIALLY my hero... MY DAD! He felt it was HIS fault because he and our family drag raced jets when I was young so I've been around and had the "aqua jones" my entire life. He had several close calls over the years of racing but never got wet. We lost one family member in his blown fuel jet in the late 70s so my injury just opened up alot of old wounds that had been festering in my family. Some things are just more important than ourselves.
Now having said that, I LOVE THESE DAMNED BOATS, LETTING THEM EAT, ENJOY MY BUDDIES WHO RACE THEM and all that goes with them. Hell I've had MANY more close calls during the 12 years I rode Harleys than I EVER have while owning boats my entire life.
Again I'm NOT judging ANYONE with my above post, I think those who know me understand that. I couldn't wait for my wife and kids to have their first 100+mph ride in an Allison via Todd in his amazing GS. I just think I kinda know what Catfish is sorta askin here...
