Paddlespeed

[dragoncity]

As I am in the expirement stage of setting up my side paddler 'Industry" I find the
observations re: paddle speed that have been made in the following
posting very interesting.

Dual Drive
========
After some consideration, and testing with a very simple direct drive setup , on a 'quick hack' boat' it became
apparent
that dual drive was the only way to go! The Industry hull is basically a 1270 mm LOA x 210 Beam
( 410mm over paddleboxes) running 155 mm dia wheel x 68 x 20mm paddles (10 floats) weighing 11Kgs,
and without dual drive would be very difficult to turn. Also there is no tendency to excess heel wilst in a turn.

Full sized experience with fixed drive shaft
=================================
I was reading an account of a early Murray P.S ( 1860's) that originaly was built using a fixed drive shaft, which
broke the shaft ( on two seperate incidents) when the heavy laden boat was making tight turns and the inner
paddle dug in while the outer paddle lifted somewhat. The owners took the hint and had the shaft replaced with
two 'half shafts' driven by their own spur gear "off the same single drive gear". The problem never reoccured.


Paddle Speed
===========
I originally was using direct drive from windscreen wiper motors ( approx 50 rpm) and without doubt
there was not enough 'push', the hull moved but no nice paddle waves were formed. After advice from a posting by
Derek, I upped the RPM's to 240RPM and that was
very excessive!, dropped to about 150 and I now get a very nice paddle wave form aft and apparently
good forward drive. ( I have yet to test this under windy conditions however)

P.S Alexander Arbuthnot (full sized paddle speed)
======================================
I was visiting the Port of Echuca ( 9/7/2002) and took a ride on their PS Alexander Arbuthnot ( built 1923),
( 76' long, 15,3" beam 10 H.P Steam engines, 46 Tonnes )
running on steam from one boiler thru 2 pistons onto direct separate drives with no differential effect ( small to
large cogs at 4:1 ratio) with 90 rpm average
input revs ( thats 22.5 RPM ) on the paddles. HOWEVER, the floats ( paddles) are HUGE at 18" high
( 4 to 5' wide I think), spaced so that as one float enters the other is leaving the water.
Just think of the force being applied to the water. This boat is capable of towing 400 ton barges, and cruises at
about 7-9 knots.

So high RPM's are not required to get the job done.


Speed Controller
==============
As I'm using 12Volts I could not find a suitable speed controller, and after playing about, I really doubt that I'll
actually need one. Stop to Full Forward/Reverse Speed doesnt cause my motors any problems, and does give very
good boat control. I've thought about testing the possibility of using 6volts as 1/2 speed , then 12 volts as full speed
using twin 6volt batteries, also by using 2 speed windscreen motors on 12 volts is a possibility. I also suspect that
windscreen wiper motors are of such quality that they can take
much higher voltages without much harm, I test ran a motor on 24volts and it ran beautifully without apparant
damage.

I personally do not like electronic speed controllers as they are fairly expensive and limit ones choice
of battery size, however I must point out that 12 volts is not a popular battery size for any controller manufacturer.
( I guess 12 volts is too large for most model applications, to small for industrial usages ( ie wheel chairs, bikes) )


Real steam speed control
====================
I was talking to a retired Ships Engineer ,who had worked on steam driven ships,
and he mentioned that 'fine' RPM control was hardly ever used, and stop, forward & back were pretty
much the only throttle settings used !!

He also mentioned that as fixed pitch screws were only 80% efficient in reverse,
they would need 120% power to get full astern effect if a rapid stop was required.

Cheers,
Brett