Anybody have actual experience running a single screw boat with a Kortz nozzle?
(no I heard from a guy who knows a guy who met a guy stuff, please)

Any discernable difference in propwalk when making sternway?

First, no, I don't have actual experience with the nozzle. I've always seen
it spelled and pronounced "Kort", but when I did a Google search with your
spelling, I did get some hits. However, if you spell it without the "z" you
get a lot more hits. Maybe you'll find some info there. :^)

Snafu

"Gould 0738" wrote in message
...
Anybody have actual experience running a single screw boat with a Kortz
nozzle?
(no I heard from a guy who knows a guy who met a guy stuff, please)

Any discernable difference in propwalk when making sternway?

On 10 Jun 2004 03:47:32 GMT, (Gould 0738) wrote:

Anybody have actual experience running a single screw boat with a Kortz nozzle?
(no I heard from a guy who knows a guy who met a guy stuff, please)

Any discernable difference in propwalk when making sternway?

That's a good question. Because if you do, it would dispel otn's
theory. I imagine you would though because of the several *root* causes
of prop walk, not all would be eliminated by korts. I.e., the one you
described out of Chapman's would still exist as would any torque force.
While otn's theory could contribute, it's only one of several factors
that may or may not be the largest contributor on any particular boat.

Steve

BG Nope, only two twin screw tugs with Kort nozzles. One is a
standard twin screw with outboard turning wheels, the other is a Z-drive
with two right hand wheels ..... reason, well for one thing, there's no
prop walk with Kort Nozzles, and for another, they turn 360* in azimuth.
Sorry I can't help.

otn

Gould 0738 wrote:
Anybody have actual experience running a single screw boat with a Kortz nozzle?
(no I heard from a guy who knows a guy who met a guy stuff, please)

Any discernable difference in propwalk when making sternway?

BG Nope, only two twin screw tugs with Kort nozzles.

You guyz must think I'm nutz to spell thiz with a "z" on the end.

Lotz of people do the same thing.

Wonder if the nozzle was invented by Kortz Marine Equipment company? That
company buildz equipment for fishboatz, workboatz, and general commerzial
craft.

Whatz your point? :^)

-Jim

Gould 0738 wrote:
BG Nope, only two twin screw tugs with Kort nozzles.


You guyz must think I'm nutz to spell thiz with a "z" on the end.

Lotz of people do the same thing.

Wonder if the nozzle was invented by Kortz Marine Equipment company? That
company buildz equipment for fishboatz, workboatz, and general commerzial
craft.

Gould 0738 wrote:
BG Nope, only two twin screw tugs with Kort nozzles.


You guyz must think I'm nutz to spell thiz with a "z" on the end.

Lotz of people do the same thing.

Wonder if the nozzle was invented by Kortz Marine Equipment company? That
company buildz equipment for fishboatz, workboatz, and general commerzial
craft.


The nozzle is a design, dating back to the 30's (in the form we now
see it) I believe and named after one of those mainly involved in the
design.
A bit of googling will come up with a number of hits including some
newer forms.
My understanding is that the nozzle removes any noticeable effect of
propwalk (feel free to read between the lines here).
On the Z-drive tug with 2 RH wheels, set the unit to 000* and put it
ahead and you have a twin screw standard boat with inboard turning
wheels (well, half of one) .... the boat should go straight ahead. It
doesn't, but immediately starts turning to stbd.
Turn the unit to (azimuth) 180* (this would be normal astern) and put
ahead and the boat should back straight. It doesn't. It immediately
starts turning (backing) to stbd ..... an indication, at least, that
there is no propwalk.

otn

Gould 0738 wrote:
Anybody have actual experience running a single screw boat with a Kortz nozzle?
(no I heard from a guy who knows a guy who met a guy stuff, please)

Any discernable difference in propwalk when making sternway?

Have operated a single screw submersible with a fixed Kort nozzle. There
was no "overhang" of the hull above the prop on either version. There
was detectable prop walk when submerged several hundred meters and
hovering in midwater where external influences would be considered to be
equal in all directions but none noticed on surface operations.

The fixed nozzle on my tug was removed (according to previous owner)
because it limited the usefulness of prop walk when maneuvering astern
in close quarters. Prop walk in this boat is awesome and must be
experienced to be believed ... useful sometimes, dreadful the other times.

Rick

DANG ! This is interesting for a number of reasons:
A. You experienced propwalk with a Kort nozzle.
B. You experience it at depth but not at the surface.

otn

Rick wrote:
Gould 0738 wrote:

Anybody have actual experience running a single screw boat with a
Kortz nozzle?
(no I heard from a guy who knows a guy who met a guy stuff, please)

Any discernable difference in propwalk when making sternway?


Have operated a single screw submersible with a fixed Kort nozzle. There
was no "overhang" of the hull above the prop on either version. There
was detectable prop walk when submerged several hundred meters and
hovering in midwater where external influences would be considered to be
equal in all directions but none noticed on surface operations.

The fixed nozzle on my tug was removed (according to previous owner)
because it limited the usefulness of prop walk when maneuvering astern
in close quarters. Prop walk in this boat is awesome and must be
experienced to be believed ... useful sometimes, dreadful the other times.

Rick

otnmbrd wrote:
DANG ! This is interesting for a number of reasons:
A. You experienced propwalk with a Kort nozzle.
B. You experience it at depth but not at the surface.

A: Which leads me to believe that the force, while limited, is also due
to the precessional force created by a rotating mass, perhaps excited by
pitching forces resulting from hull shape in the case of a submersible.

B: There are far more stronger forces acting on a submersible on the
surface.

Rick