electricity-free bilge pumps

I am trying to find information on bilge pumps that work off natural resources, like wave motion, rather than electrical or battery power. It is intended for use in a small keelboat. I would love to hear your ideas/information.

 

When I apprenticed, as a kid, the old timers told me the fastest bilge pump is a scared sailor up to his knees in water with a bucket in his hands. That said, I could see a pendulum system running a diafragm pump. As for wave action, a float on the side connected to the pump arm would probably work too.

 

....so lomg as there's waves......

 

Thanks for the ideas! I know all about bailing with a bucket - I served a similar apprentice in a sailing dinghy! I like the pendulum idea - was also thinking perhaps solar panels but they are quite expensive, and I only have 100 euro to spend...

Now to the drawing board...
whitecj