[hpv-boats] Propulsion ? How do you change from pedal to propeller or do you?

[mark McWilliams]

How do you change direxction of the pedal motion right angle(s) to accommodate a propeller?
If you use some sort of right angle gearing where did you find it or did you make it?
If the use of a propeller is to complicated what other means are commonly used among this HPV-boats group?
I would like to find a small right angle drive that I can put in the water and a second that I can somehow connect to the one driving the propeller and drive with a chain  connected to pedals so that I could better vary the gear ratio between the pedals and the propeller.

If varying  the gear ratio does not seem that important then at least I want to really up the RPM's of the propeller at least into the many hundreds of rpm's while keeping my cadence under 80 rpm. My legs feel like limp noodles if I try to keep a cadence over 80 rpm for long but I can easily do 60 to 80 all day long day after day hours on end.
Also I hope to use this on the river so there is the up stream against the current and downstream with the current aspects of a pedal boat.