Pedal power

I don't want to hijack this thread (http://www.norcalkayakanglers.com/index.php?topic=80230.0) as it's in regards to mounting a Hobie system.  But there's pics there that I've been trying to figure out how to do for a while.

Does anyone know how to build the "drive" (the big arrow) in the below pic?  And what type of "head" or shaft would I use to accept power from the "drive" (the small arrow).  Has anyone put this together yet? 



I've seen a few pics about them online but no "how-to" or specs on it.  I know about the NuCanoe and h2pproped models but similarly to the OP in the other thread, feels like I can build this for less than $800.

I too have an Ascend 128T but do not want to attempt any hull modifications.

Thanks.

Totally reminds me of how a gear driven cable works for a speedometer on a car. If u got a shaft being driven by the bicycle crank. At the end of the shaft is a gear connected to another gear that powers the drive cable to the prop.... all that exterior stuff is just a bracket and casing . Hope that helps.

Google  The Gearbox. Adventures of Greg for a video of the bicycle chain ring and 90 degree gearbox setup.
T 10 belt drive on v15-58 pedal boat is Rick Willoughby's latest pedal drive system. Google him for pics of his pedal drive boats.
The T 10 system does away with the bike chain wheel by running crank power direct to the gear box. This is the system I am most interested in but it might be difficult to "convert"  an existing yak for it. Ricks boats are designed from ground up to use his pedal systems.