Quote Originally Posted by FLATS ONLY View Post
They were not all failure of material. Installing propellers & making correct keys for each prop is what's important. Installing the propeller correctly is where it's at.
I heard as well that Gary H shaft failed due to the prop not being installed properly. However, Gary did fail a shaft the year before towards the end of the race. You don't go that long with that kind of power with a prop installed incorrectly. That said, there is ALOT to be said about the fitment of a prop on the shaft. If the prop is too dependent on the key to control rotation, it is going to be more prone to failure at the shaft, and even the prop hub than if the taper takes the brunt of the load.
Husky motorcycles for decades use a tapered shaft with no key for the front sprocket. You could break chains, blow clutches and transmissions, with all the hammering of a motocross or desert race and never move that sprocket on that tiny ass shaft. Get wrong, the shaft would be a scored POS in no time.
Way too many people over look the benefits of lapping a prop to the shaft too greatly increase the holding power of the taper, and get the load off the key.
The Bloodshot Schiada just had a shaft diameter not up to the task, as well as have may extended to far from the shaft in an effort to get to carry the nose.

I never bought into the idea the material was at fault. AQ22 has been used too long to blame it, unless someone could prove the material was something other than AQ22.
I will agree with Westeraero that improper machining methods can wreck havoc on the best material you can buy. If you start looking at the machining as being every bit as important as welding some exotic material, and you should, then you will become a little more conscience of how your shaft is made.
I have always got my shafts from Bob at Glenwood, and had excellent luck with them. I will give a lot of thought to where my next one is made.

Output shafts, prop shafts, and props have been the number one killer of the inboards in the Parker enduro since day one. In one year, it was 3 output shafts, including ours. There is one common thread in these boats that is overlooked as well. In a GN race the engine is primarily operated well above peak torque and deep into peak HP RPM. In the enduro, many of the engines are being operated too close to peak torque in a effort to reduce fuel, and "save" the engine. IMO, its a mistake.