creative non conventional powered boat ideas

hi everyone

have you ever heard of rubber band powered boat,balloon powered boat, candle powered boat and so on? it is creative and fun toys for children to be played.
if you haven't see it, you can take a look in youtube.

my purpose of posting this new thread is for us to share our ideas on how can we create a non conventional powered boat to generate creative and innovative mind.

 

In India they have these interesting lightweight plastic cars that are powered by compressed air. You have to "recharge" the air tank every night with an air compressor. Good for large polluted city.

it is like the variation of the balloon powered toy, but larger. Could power a boat that way too.

There are very few energy souses that are as compact and as energy dense as a tank of diesel fuel. It is even more cost effective to operate than a sail boat for the purposes of moving freight.

How about a "fitness" cruise line where passengers take turns on a bank of pedal bikes that drives the boat. The passengers actually pay you to power your cruise boat, and they loose weight and get in shape on the way.

 

Here's one: http://www.sailwings.net/windspinner.html

 

I've always felt, somehow, someway giant flippers or

just oars could be adapted for use with circular motors.

After testing pedal powered prop driven kayaks, the Hobie system, and just regular kayak paddles, I'm convinced a prop losses a lot just churning the water.

In contrast a paddle was almost like a mechanical connection, or like 'poling' by spiking a pole on a shallow bottom.

I'm thinking large flippers(like on the Penguin's submarine in original Batman movie) could move larger 'chunks' of water for propulsion without all the energy wasting churn and turbulence.