[hpv-boats] Right Angle Drive

[Tony Nelson]

Rick Willoughby <rickwill at ...> writes:

> 
> There are a few manufacturers of angle drives.  Mitrpak are possibly  
> the best value.
> http://www.mitrpak.com/product_datasheet.php?product_id=34
> 
> The best size prop will be spun at 4 to 5 times cadence.  You can use  
> a large diameter prop turned at 2 to 3 time cadence directly from a  
> gearbox but the box costs quite a lot.
> 
> You can also use twisted chain drives.
> 
> You can pair two boxes with 1:2 steep up to get combined 1:4 but this  
> ends up very expensive.
> 
> There is a thread on this forum that has a huge amount of detail with  
> photos if you care to wade through it:
> http://www.boatdesign.net/forums/boat-design/pedal-powered- 
> boats-23345.html
> 
> Rick Willoughby
> rickwill at ...
> 
> 


No-Worries:: the gearboxes suitable for adapting to "Human-Power" are 
plentiful. cheap [free], rugged, but not marinised. 
Angle-grinders provide them, burnt motors with smoothly run-in gears ; I've 
gutted about 20 of them, they are usually 3 to 4 to one, common makita is 
3.3,which I find optimum. The highest ratio I've found is a 9::1, but that 
was 'stripped'
The'trick' is to make an adaptor for fitting a cluster [I use 14-18 tooth] 
onto the shaft where the disc was [maybe remove the ratchet mechanism] ; 
struggle & fight to remove the rotor windings; cut this motor-shaft short & 
make a coupling [about 9mm id]
For a pp boat, have the chainwheel on the right side of a 'crankshaft; so the 
chain passes behind the operator to a cluster [enabling variable ratios]- a 
shaft across to the centre-line, where the g/b increases speed / changes 
direction / feeds aft to the prop-shaft. via a seal & universal-joint.
Use a bigger chainwheel for higher RPM output.
Ok so I made one  -almo0st - figured a better solution - I'll tell you when I 
have it!
Surfing on the Bare island Bombora in a pp-Kayak on Botany Bay in Oz; watch me 
go!
Tony Nelson.