[hpv-boats] human powered yacht?

[Rick Willoughby]

Sam
In the event you get around to thinking about propeller systems  
again.  You may be interested in something I made for a large  
catamaran.  There is a particular yacht race here where human power  
is permitted as it is a combination of sailing and athletics (running  
up mountains) - called the The Three Peaks Race.

I mounted a gearbox with pedals over the stern of the catamaran using  
a curved shaft.  Picture here:
http://www.rickwill.bigpondhosting.com/Pecadillo_Pedal_Thruster.png
I initially tested it with an 800mm diameter large model plane prop  
and had buckling issues with the curved shaft due to the high thrust  
load and low rpm.  I then reduced the flexible portion of the shaft  
to about 1500mm and mounted this off a 1200mm length of aluminium  
tube.  For this shaft configuration I made a 4-bladed lightweight  
metal prop that was 600mm diameter.

In testing with the latter set up I got the 8 tonne catamaran to  
2.7kts working within my aerobic limit.  It was surprising how much  
difference having a dagger board partially lowered made to the drag  
due to the offline thrust.  This was in line with my prediction and  
translates to 4kts with two drives.

This year the pedal system was used in conjunction with oars.  The  
pedal system was as effective as two rowers while adding the pedal  
power to the rowers increased speed by about 50%.

The catamaran owner has since asked me to make a system using two  
gearboxes similar to this one:
http://www.rickwill.bigpondhosting.com/OW_Drive_Leg.jpg
This unit was made for a 400kg boat and has got that to 6kts - all  
day speed is around 4kts.  The unit for the catamaran will have a  
bigger prop and deeper leg.  It will be more compact for storage  
purposes than the long curved shaft.  If it tests out well then there  
will be one made for each hull.

I am able to do quite accurate performance predictions for these  
systems based on the hull shape, displacement and the drive system  
design.  For a small yacht you could get quite good results sitting  
across the cockpit with a drive leg below the hull and prop driven  
directly by a chain.  There are some very economical model plane  
props.  This one is similar to the big one I used initially:
http://www.hobbycity.com/hobbycity/store/uh_viewItem.asp? 
idProduct=11967&Product_Name=TCF_27X10_HighPrecision_Carbon_Fiber_Sport_ 
Propeller


Rick Willoughby

Hi All

I have a 22 ft kingfisher yacht http://www.kyoa.org.uk/k20 
+technical.htm  I
am interested in powering it partly through human power when I am on   
inland
canals etc.

I will also have a conventional outboard for when I get tired!

I plan to make a Yuloh http://simplicityboats.com/yulohpage2.html  
which I
would hope to be able to use for about 2 hours a day. eg
http://www.youtube.com/watch?v=u7MQsdLpWaM

In addition seems to make sense to use your more powerful  leg  
muscles to
power the thing. I realize that the boat will not move fast, and that it
will be hard work.

The boat has an outboard well inside the boat and I am hoping to be  
able to
make use of that to install a pedal system.

1) Has anyone ever fitted a mirage drive to a boat this big? With what
results?

2) I am aware of the escargot
http://www.mission-base.com/pedal-power/pp_escargot_photos.html are  
there
any other large pedal powered boats out there?

3) I have had a browse on these archives, and have seen people making  
props
out of model aeroplane propellers, would the prop need to be longer  
for such
a heavy boat?

4) I am thinking of aiming for this kind of set up
http://www.openwaterbike.com/components/drive-units/mark-drela-drive- 
system I
thought I might start with this cheap gearbox
http://www.maplin.co.uk/Module.aspx? 
ModuleNo=43541&C=Froogle&U=43541&T=Module
and
upgrade it later if the boat actually moves under pedal power.

Any comments or suggestions?

Thanks

Sam