Prop Shaft

[gn7]

I have theory on that. The hydro prop will still have a consistent load even though its not even. It would be a forward from the bottom force. Probably trying to bend the shaft up in the middle. But an uneven load from a prop that has different bite from each blade would have a different force on the shaft depending where the good biting blade was. Good blade on the bottom forces the shaft up, good blade at the left shaft forced right, good blade at the top shaft forced down, ect. I could imagine the shaft looking like a jump rope when it was under a load.
Just an opinion.

Not even close. The prop is running off/on the whole time.
When the ONE blade is headed down, it is doing the vast majority of the work to the point it passes straight up and down. Then its doing progressively less, while the other is beginning to do progressively more. But when they are dead horiz, neither is doing shit. No prop is loaded and unloaded like a hydro prop, and its only worse the more power you put to it.
With the twin props, they are arranged 90* out of sync, and the forward thrust is relatively even, although still off and on per side during the run. The fact they are counter rotating helps immensely with the stability of the boat, and counters the "side walking"

You can see the on/off in the rooster tails. This is actually a mild case.