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-   -   Seamanship Question #16 [Props again] (https://www.boatbanter.com/asa/25611-seamanship-question-16-%5Bprops-again%5D.html)

Scout November 30th 04 11:56 PM

do you deny the existence of tuna fat?
Scout

"Horvath" wrote in message
...
On Tue, 30 Nov 2004 00:49:47 GMT, "Scout"
wrote this crap:

It may be mixed with tuna fat to form a handy paste.



I've never seen fat tunas.





Pathetic Earthlings! No one can save you now!




Horvath December 1st 04 01:36 AM

On Tue, 30 Nov 2004 23:56:54 GMT, "Scout"
wrote this crap:

do you deny the existence of tuna fat?
Scout



I've never seen any.



"Horvath" wrote in message
.. .
On Tue, 30 Nov 2004 00:49:47 GMT, "Scout"
wrote this crap:

It may be mixed with tuna fat to form a handy paste.



I've never seen fat tunas.



Pathetic Earthlings! No one can save you now!

Jonathan Ganz December 1st 04 01:41 AM

In article ,
Horvath wrote:
On Tue, 30 Nov 2004 23:56:54 GMT, "Scout"
wrote this crap:

do you deny the existence of tuna fat?
Scout



I've never seen any.


Your tits get in the way!



--
Jonathan Ganz (j gan z @ $ail no w.c=o=m)
http://www.sailnow.com
"If there's no wind, row."


Peter Wiley December 1st 04 04:28 AM

In article , Capt. NealĘ
wrote:

Aluminum is relatively worthless for a boat hull.

All it takes to completely destroy the hull of an
aluminum hulled vessel is a handful of mercury
past smeared on it. It will begin to turn to dust within
hours, break apart and sink.

A stainless steel boat is impervious to just about
anything but strong acids.


Bwahahahahahahaha. It's obvious you know SQRT(f**k-all) about
metallurgy. S/steel is not a good metal to have in continuous contact
with seawater.

My biggest objection to aluminium is that its abrasion resistance is
low compared with steel and its ultimate failure point is too close to
its deformation point. Steel is a lot more ductile but does require
good barrier coats to keep rust at bay.

If money is no object, you build out of cupro-nickel.

PDW

Joe December 1st 04 04:13 PM

Peter Wiley wrote in message ...
In article , Capt. NealĘ
wrote:

Aluminum is relatively worthless for a boat hull.

All it takes to completely destroy the hull of an
aluminum hulled vessel is a handful of mercury
past smeared on it. It will begin to turn to dust within
hours, break apart and sink.

A stainless steel boat is impervious to just about
anything but strong acids.


Bwahahahahahahaha. It's obvious you know SQRT(f**k-all) about
metallurgy. S/steel is not a good metal to have in continuous contact
with seawater.

My biggest objection to aluminium is that its abrasion resistance is
low compared with steel and its ultimate failure point is too close to
its deformation point. Steel is a lot more ductile but does require
good barrier coats to keep rust at bay.

If money is no object, you build out of cupro-nickel.

PDW



Whats cupro-nickel? And why?

I hear nickle copper is best, the copper is a perfect antifoulant.

Joe

N1EE December 2nd 04 01:07 AM

The larger the vessel the more difficult it is to
manuever and stop.

I wanted to be clear the issue in this question
was with respect to backing down. The thrustors
provide good side-to-side control and eliminate
that factor from the question. Could it have
be written more clearly?

The variable pitch allows the throttle to be
set and forgotten while pitch controls linear
thrust--magnitude and direction.

There are no worries about engine stalling while
changing gears, or cables jamming or snapping,
all of which have happened to me in the past, and
each of which could be bad news docking and
manuevering a mega yacht.

Bart Senior


Nav wrote
otnmbrd wrote:

Nav wrote:

There's no need for variable pitch -which is why you don't see it in
mega yacht thrusters


Cheers FT.



I believe the discussion regarded the Main Engine, not the thrusters


I thought it was 'bout the whole propulksion package 'cos he mentioned
dual thrusters. If just about main engine that's a really boring question.

Cheers


Peter Wiley December 2nd 04 01:57 AM

(Joe) wrote in message . com...
Peter Wiley wrote in message ...
In article , Capt. NealĘ
wrote:

Aluminum is relatively worthless for a boat hull.

All it takes to completely destroy the hull of an
aluminum hulled vessel is a handful of mercury
past smeared on it. It will begin to turn to dust within
hours, break apart and sink.

A stainless steel boat is impervious to just about
anything but strong acids.


Bwahahahahahahaha. It's obvious you know SQRT(f**k-all) about
metallurgy. S/steel is not a good metal to have in continuous contact
with seawater.

My biggest objection to aluminium is that its abrasion resistance is
low compared with steel and its ultimate failure point is too close to
its deformation point. Steel is a lot more ductile but does require
good barrier coats to keep rust at bay.

If money is no object, you build out of cupro-nickel.

PDW



Whats cupro-nickel? And why?

I hear nickle copper is best, the copper is a perfect antifoulant.


http://www.technicalmaterials.com/me...ro_nickel.html

Same stuff, just you got the name wrong. Look it up in Lincoln's
welding handbook and you'll find that you can weld it with MMA using
ECuNi rods, good weldability. Ditto for GMA welding, GTA welding and
fair welds using carbon arc tho why you'd bother is beyond me. Preheat
not required, no fancy techniques needed unlike aluminium or s/steel.
Good mech properties. Pretty much inert so no real corrosion probs and
as you noted, naturally antifouling.

Real problem is the price. Friend of mine's brother is a scrap metal
dealer, got 2 tanks of Inconel one time for the price of s/steel. Wish
I'd have known him back then, I woulda bought them off of him and
saved the sheets for a hull.

PDW

N1EE December 2nd 04 02:05 AM

I agree. Aluminum is light and the cost of
steel is high right now. Two of my friends
are rebuilding and old steel boat into an
Oysterboat, and constantly complain about the
cost of steel.

Bart


Nav wrote

Stainless steel is not a cure all for corrosion problems -it's also
heavy for a yacht. Aluminum seems a more common solution.

Cheers


otnmbrd December 2nd 04 04:46 AM

N1EE wrote:
The larger the vessel the more difficult it is to
manuever and stop.

I wanted to be clear the issue in this question
was with respect to backing down. The thrustors
provide good side-to-side control and eliminate
that factor from the question. Could it have
be written more clearly?

The variable pitch allows the throttle to be
set and forgotten while pitch controls linear
thrust--magnitude and direction.

There are no worries about engine stalling while
changing gears, or cables jamming or snapping,
all of which have happened to me in the past, and
each of which could be bad news docking and
manuevering a mega yacht.

Bart Senior



It's not quite that simple.
First off, thrusters quickly lose their efficiency, as soon as you start
moving ahead/astern. You need to keep your speed (generally) below 4K
through the water to maintain good thruster power.
Since it's difficult to make a prop that is really efficient, with a
simple flat blade, most variable pitch will tend to walk to some degree,
at all settings .... good news is it's always the same direction. Also,
especially with use, most variable pitch will pick up a tendency to
"creep" either ahead or astern when the settings are at zero pitch, so
you end up having to "tinker" with the controls.
Overall, I have a Love/Hate relationship with variable pitch. In some
cases I'm damn glad I had it, while in others, damn glad I didn't.
Naturally, if it's the one system you are using, many of the minor
drawbacks will become second nature for you to use or avoid.

otn

Rick December 2nd 04 12:23 PM

No props. A set of Kamewah water jets.

Rick



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