[hpv-boats] converting pedal power to prop power right angles

[Rick Willoughby]

Mark
There are quite a few right angle gearbox manufactures.

You can use smaller boxes with 1:1 ratio and bicycle chain speed  
increase on the input.  Mitrpay range is probably the best value around:
http://www.mitrpak.com/product_results.php

Marcoplo boats are offering a modified Mitrpak box that accepts cranks:

http://marcopoloboats.com/MitrpakDrive.html

This box has a 1:2 ratio that is a bit low for a fast boat.  I prefer  
a minimum of 1:4.

You can purchase nice gearsets from this place:

http://www.qtcgears.com/RFQ/BevelGears.htm



I have used two Mitrpak boxes to make complete drive legs for a few  
applications now.  These are really nice but also end up expensive  
per the unit pictured here:

http://www.rickwill.bigpondhosting.com/folded_pedal_thruster.jpg

These units use a modified T-122 for the top box that accepts cranks  
and a standard R-101 on the bottom.  This gives an overall ratio of  
1:2, which is ideal for swinging the 30X20 prop with two units  
pushing the 8t sailing catamaran.

You can get 1:4 ratio using two of the Mitrpak boxes as seen here:

http://www.youtube.com/watch?v=OXSZLt_6eFg&feature=related

You need to get to 6 minutes in before you see the top box.  The  
bottom box and prop are partially visible in the shots on the trailer  
at the beginning.

There are other ways to get the right angle drive including twisted  
chain, twisted belts, flexible shaft and magnets. Each method has  
pros and cons.



Rick