Originally Posted by markpierce
What about complication, potential for failure, and additional burden of maintenance cost? Are they 99.99% reliable?
Well, they aren't on the Washington State ferries.
I suspect that the size of props needed to move boats like ours and the power it takes to move them would not lend itself to the use of a simple folding prop where inertia holds it out under reverse. I have seen this kind of prop used on the get-home shafts of Nordhavns in the Seaview Yard but they are very small like the sailboat props.
My guess is that to provide variable pitch and feathering for a boat like ours the prop's pitch mechanism would have to be some sort of a mechanical system either electronically controlled or manual. And this would for sure add to the elements Mark speaks of.