Paddlewheelers various

[Derek Warner]

Hi Stuart

Today's PD postings have a selection of recommendations - "like I did this xx years ago but it didn't work" & here is another

I would also opt away from delryn, nylon or any of it's Du Pont cousins - they are all unstable ie., high expansion rates for little
temperature increase as compared to bronze etc (20 years ago I tried nylon for the prop shaft stern tube bushes - absolute waste of time

(motor current consumption doubled as the bushes grew & provided tighter diametrical clearance over the prop shaft) - I could get access to the external (rudder side) bush to replace it in sintered bronze, however the stern tube was 5/8" diameter copper tube about 2 1/2"long and epoxied into the hull - required a hacksaw and 4" mini grinder to get the tube out!

So with Decoy I have paddle shaft bearing tubes epoxied into both sides of the hull - each about 1 1/2" long with a 1/4" ID x 3/8" long sintered bronze bushes Loctited in on either end - and each bearing tube has a 1/8" diameter copper tube riser soldered in (which will be extended to about 3") and should hold sufficient light lubrication oil - for a days running (and yes I am running 1/4" precision brass as the paddle shaft and sintered bronze bearing elements)

regards Derek

[Paulrjordan]

Excellent! As we have come to expect from you, Derek, a very
interesting thread and a topic which I often mull over. Now again let
me make it CLEAR I do not have nearly the engineering background you
are blessed with, so I tend to be a little, shall we say, "basic" in
my approach to these things. However, the set up you use is pretty
close to mine.

My first observation when building the paddle shafts is they don't
need to be supported at the outboard edge of the sponson...you cant
anyway with a feathered wheel but on a simple wheel (which is what I
build) I have this paranoia about outboard weight maybe contributing
to the paddler "waddle" or "wobble" syndrome as it has been called. I
may be wrong on this but I once did an experiment placing weights on
the edge of each sponson to see what would happen. Try it!!!..I think
it's called the "teeter-totter phenomenon!

Second observation is that, unlike conventional screw vessels, our
drive RPM is far slower...not much heat going to build up between
60-180 RPM ! Although heat is not a critical factor in the paddler
drive train, resistance (friction) and lack of symmetry ARE. This can
substantially transmit increased load back to the motor (hello
nasty, unwanted AMPS!) because of the exaggerated diameter of the
paddlewheel. Given the same shaft torque...is it easier to stop a
paddlewheel or a propeller with your finger? Put it this way..the
paddlewheel is far LESS painful!

On my twin engine set ups my preference is for stubby shafts (just
enough to mount a pulley or gear on the inboard side and extending 50%
into the wheel), fairly thick ( 5/32 works well for me on a 4" wheel)
and with absolutely NO chance of "wow" (engineering grade polished SS
rod). I'd like to try SS TUBE sometime to maybe save a little weight.
I try to keep the weight of the drive shaft as inboard as possible.

By the way, I also made an observation from old paddlewheel drawings
of the 19th Century! Those shafts are pretty "meaty" I'd say and I
would love to hear from our experts as to what the typical diameter of
these drive shafts might have been.

Now for bearings..again at our RPM, although I'm very conscious of
friction, I take a pretty simplistic approach to all this. Less metal
to metal = less friction..right?

Working outwards from the 5/32 o/d SS shaft, I insert (or you can
solder) a 5/32 i/d x 1/4" long brass main bearing in each end of the
1" long paddle shaft bearing tubes. The bearing tube gets epoxied
dead level into the hull with appropriate support and with the outer
end flush to the hull exterior. The inside void of the tube is
filled with lithium grease. If you've soldered in the main bearings
you can top the shaft bearings up through a filler tube through the
outer casing just as Derek described. I like that as it makes a more
permanent seal at the shaft and now do it on all my boats. The paddle
wheels seem to spin very well with this set up, and it's all
watertight against splashing.

I must say I'd like to experiment with some ball race bearings I have
in the tool box, but for the time being I'll stick with what I know
works. I'd be most interested to here more from anyone who has
thoughts on this and maybe a diagram or two we can post in the files
section.

Keep those wheels a turnin', "Proud Mary keep on......" funny how that
CCR classic has even greater meaning to me these days ! We REALLY
should adopt it as our Paddleduck Anthem!!

Have a great (friction free) weekend to all of you..everywhere!

PJ

[Derek Warner]

on January 19, 2002 <paulrjordan@canada.com> wrote

>let me make it CLEAR I do not have nearly the engineering background>

now hold on PJ - we only have to look at certain paddleducks files and circuitry
re single servo dual engine control!! etc and functional electronic schematics
designed for non electrical orientated people (my self included)

>Those shafts are pretty "meaty" I'd say and I would love to hear as to what
>the typical diameter of these drive shafts might have been

When at Mannum in South Australia a few weeks ago (to see the hulk of PS Decoy)
I went on board the fully restored and functional PS Marion (built 1897 - 157 Gross)
took plenty of snaps of her engine & engine bay - paddle shaft estimated as 4"
diameter - naturally the paddle shaft is in three or four sections and joined by
mechanical pin type couplings that were say 10" diameter
>
> Now for bearings..again at our RPM, although I'm very conscious of
> friction, I take a pretty simplistic approach to all this. Less metal
> to metal = less friction..right?

Technically correct, but less bearing metal to shaft metal (which always should
have a film of lubricant between the faces) = less bearing area = higher bearing
pressures and loadings = higher heat

Before ordering the Sinterlite bronze shaft bushes for Decoy I used the manufacturers
data loading calculation sheet - so a pretty good rule of thumb for stern or paddle tube
[solid] bearing selection appeared to be to maintain the shaft diameter as each bearing
element length

Rip apart any old [dead] kitchen appliance, daughters hair dryer, cheap powertools etc,
they all seem to have bushes where the pin diameter = bearing length

Decoy has a 1/4" paddle shaft, but I chose 3/8" long bushes - should outlast my infant
grandson
>
> The inside void of the tube is filled with lithium grease. If you've soldered in the main
> bearings you can top the shaft bearings up through a filler tube through the
> outer casing

Twenty years ago I settled on Castrol water proof grease for stern tube applications.
Many models in the local pond left an oil slick (from too light an oil or too high stern tube
bearing clearances) - they also use this water proof grease for boat trailer bearings etc,
and it is easily injected to the paddle shaft tube riser with a plastic needle holder
(without the needle) all Pharmacies are more than happy to sell you one for $1.00 as long
as you don'y ask for the sharp pointed bit to go with it

regards Derek