Rolling hulls

[JonathanCole]

This is probably a really dumb question because I searched BD.net on this topic and came up with nothing. But since I have actually seen rolling hulls employed on simple pedal boats, there must be some information out there about how to calculate their performance, efficiency, etc.

On the plus side having a very large surface area to couple with the water may have the benefits of low rotational speeds as in a paddle wheel drive. If the hulls are also the drives, then the issue of wetted area may have to be thought of differently as such hulls roll instead of simply splitting and pushing the water aside. On the other hand, the lifting of water by such hulls is exactly the opposite of the desirability of minimizing wavemaking. Every ouce of water lifted above the waterline is work that does not in and of itself move the hull forward.

Rolling hulls can include blades, either articulated or not. They can roll on axes perpendicular to the direction of the boat (as in most pedal boats) or parallel to the direction of the boat which would require some sort of helical texture or blades on the rotating hull.

Anyone have any ideas on this.