how about a "row" boat but instead of oars, like Hobie-Drive fins but at gunnels?

Sort of like leeboards, but with handles.

Unlike the flexible Hobie fin scheme, the 'pitch' would be simple mechanical 'flip flop' and cant the oar maybe 15' either side of 0' for up and down strokes.

For sailing or just stablity, they could double as leeboards.

Depending on size of boat, more than one person could operate each oar, most likely a t-handle for motion from ankle height to 'hands over head' and back down.

Depending on size of boat, they could also double as gang planks.

The idea would be to have same "always thrusting"(no recovery stroke) as Hobie Drive, but something you could put on a boat without a hole in the middle.

I'm thinking of about 25' long, 8' wide dory, with oar about 8' past the gunnel, and shaft bent about 45' at the gunnel so handles at ankle height would have the tip of blade barely in water and handles at 7' 6" above floor would have the oar a bit past vertical under the boat.

I think this might take a lot less skill that regular oars, and be able to be operated by anything from one strong man to maybe 4 smaller people on each oar(no need to go to 7.5ft heigh).

Should also be able to easily change the 'gearing'(pitch angle) on the fly.

Might look sorta like a penguin with wings flapping on the sides.

 

How about a stern mounted Mirage drive instead? It could use flex cables to drive it like the H2Pro-Ped. It would be a manually powered outboard.

A big advantage of the Mirage is its mechanical simplicity and light weight, which would be sacrificed in such an arrangement. Facing backwards would help, because you'd basically just have a Mirage with a longer, L-shaped shaft. For that matter, you could put it on the bow instead of the stern and face forward. How about a push-me-pull-you canoe?

Of course, a yuloh has no return stroke.

 

Funny you should say that Tom, I saw just what you describe entered in the amateur boat building competition at Beale Park boat show in 2013 - It was a standard Mirage drive mounted on the transom of a custom built wooden hull (I think it might have been a Francois Vivier designed 'Aber', perhaps someone here knows more about it). Cables linked from pedals to the Mirage drive unit. Avoids cutting a big hole in the bottom of the boat and I think it hinged up for grounding.

Also at the same boat show was Dr Chris Waite's clever boat that has a yuloh operated by a couple of bits of string linked to simple pedals. The same boat can also be rowed or sailed. Several of us went for a river and canal cruise after the show finished, here are a couple of pictures of the yuloh system in use, taken from our own boat that was being rowed.

 

I like the idea of a yuloh for small sailboats. Small, easily stowed, kickup when grounding and great levered rudder when returning through surf.

For all it's practical advantages it seems too inefficient to be a primary propulsion. I think an improvement would be a more vertical high aspect foil, like half a tuna tail with a broader sweep. The turning force would be countered by a double paddle, or just another tail just ahead on the first.

 

I'm surprised those two wiggledrive guys haven't spotted this thread and taken over with their arguing.

I've always wondered if anyone has scaled this up any amount to run off a diesel.

 

thx for the suggestions, but I'm stuck on "Penguin Oars" for now.

I'll try to post a rough sketch soon.