SS Trillium

[jamesgardiner]

Hi Folks Question On the paddle boxeson the out side where pattern
openings, enlongated slats about 7 ft in length?? Where they used so
that when the paddle wheel was moving there less resistance
therefore, less energy used? Any answers? Thanks Jim G

[Paulrjordan]

Hi Jim...do you mean openings IN the paddle box outboard surfaces or
is this something ON the boxes?

Regards

PJ
"Sweltering in BC"

[B Worden]

If you're talking about the radial openings above the name "Trillium," then
the answer is that paddle boxes normally have plenty of vents in the
outboard side to let water out. If the wheel is bringing up a lot of water
into the box (on start-up, for example), efficiency can suffer if there's no
easy way for the water to get out. Such vents are less necessary if there's
excess clearance in the box, which serves much the same purpose. The radial
pattern is common and pretty, but horizontal slots work as well, as would
almost any shape openings.

Bill Worden

[Paulrjordan]

Hi Bill ..and Jim:

Those openings in the paddle boxes have always intrigued me. As you
say, Bill, they're definitely for venting but I've actually heard two
theories and often wondered which one is correct (or maybe they both
are!)

Some say the openings are for venting OUT or releasing high pressure
building up inside the boxes from the upstroke of the blades. On the
other hand I've heard they are for venting IN to equalize the vacuum
inside the paddle boxes created by the downward stroke of the wheel.
In fact I read (somewhere) that an unvented paddle could make a ship
unstable and create a permanent list or an alarming rolling action
(the classic "paddler waddle!") as it tends to make the box suck down
onto the water surface!

Maybe there's a bit of both these actions going on inside the paddle
box. I know you can hear alot of air movement from the vents but I
can't remember if it's sucking or blowing!

I'm eager to hear from any PD's who have further information (or even
their own conjecture) as to the way paddle boxes "breathe"!

PJ
Victoria, BC Canada

[Derek Warner]

In PD’s on Tuesday, 17 August 2004 3:48 PM - PJ responded back to Bill &
Jim & said

I'm eager to hear from any PD's who have further information (or even
their own conjecture) as to the way paddle boxes "breathe"!
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>

hi Pd’s - if we go back to basics the slat openings [radial or
horizontal] were to provide an equalization of air pressure between that
of the outside the paddle box to that of the inside of the paddle box

So with the water being drawn up into the paddle box from the paddle
floats we must displace [in a perfect world] an equivalent volume of air
– we could consider that the air will simply be displaced downwards
toward the lower level of the paddle box but for that to happen WORK has
to be done & less WORK is needed if the paddle box’s can vent the volume
of air near to the top of the paddle box etc

again as Bill wrote

Such vents are less necessary if there's excess clearance in the box

Yes - we could consider a paddle box & paddle wheel to be ½ of a
hydraulic vane pump, however naturally with much greater clearances & so
whilst a paddle box & paddle wheel would never generate water pressure,
in theory the assembly must build up a higher differential air pressure
inside the box than that of mother natures atmosphere on the outside of
the box

So for my money, the slats breathe out air & the splashing of H2O from
the slats is just a consequence of the design – but doesn’t it look
great! – regards Derek

[jamesgardiner]

Hi paul Yes I mean the out side serface open to atmosphere.Thanks
Jim G

[Tony Mattson]

On the subject of venting paddle boxes, there is a photo of the
cdouble ended side paddle ferry Eagle in the PS Eagle folder, that
shows her very heavily laden on Auckland Anniversary day around a
hundred years ago.

Aside from the gross overloading, the picture also shows water
venting in large volumes from the paddle box vents. In this example
the ferry is sufficiently heavily loaded that the sponsons are at the
water line and the paddle box bottoms are, in effect, sealed by
water.

So here's evidence of venting the paddle boxes of water as well as
air.

Kind regards
Tony
Auckland, NZ

[Alistair Deayton]

Yet the Elbe paddle steamer fleet at Dresden have no vents in the paddle
boxes, although some of the steamers have painted vents, which have varied
in design over the years and can easily be altered for e.g. a steamer's
centenary

Alistair