Flapping Foil on a real ship

Tom, here is an example of rotating propulsion by a water creature, but I don't if it counts since it appears to involve a pivoting joint rather than a rotating one: The Bacterial Flagellum: Reversible Rotary Propellor and Type III Export Apparatus http://jb.asm.org/content/181/23/7149.full Power would appear to be a crude electrical basis (proton instead of electron movement)?? Scroll down to the sketch for a quick summary.

PC

 

My thoughts were along the same lines.

But they did say inland navigation, where I suppose the quantity and quality of things to foul it is somewhat diminished.

Seals of some sort could be used, to be sure. Who knows how much complication that would add.

For a smaller craft than they mentioned this sort of drive might help where the boat is likely to be left on some tidal beach. It may also be useful where they get real testy if you damage the sea grass (or some such) and it doesn't look like it will slice and dice sea life the way a prop will. Of course a paddlewheel shares the ladder pluses and would require less draft.

 

Hi alan craig! Are you still interested in flapping foil proulsion?
Please look Flapping Foil https://www.boatdesign.net/threads/flapping-foil.62824/

 

There are ways of simplifying this system. They may come at the cost of some efficiency, but the trade-off may be worth it.

I doubt this system could ever be as efficient as a good prop. But it may be better than a not-so-good one. Like a feathering propeller for example.

There may be a place for such a system on a future sail-engine hybrid ship. A conventional prop, with its twisted blades, causes a discouraging amount of drag on a sailboat.

 

I completely agree with you.
Вy the way there is one more incentive to use the flapping foil propulsion system
on a sailing ship - if the drive is electric, then it can be used without any design changes
as hydro-generator to recharge batteries.
Such a hydro-generator, unlike a rotary turbine, will operate at low speeds.