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What is the cost of having a true Kort nozzle machined by a CNC?
I think a 30% improvement in thrust for $30 would be great but I
suspect machining a Kort is going to equate to many hundreds of
dollars, if not reaching beyond a thousand. When I look at the
Snoopy underwater videos it is difficult to imagine a kort nozzle
really making any difference in the operational experience given
that the motors are operating very slowly and pushing Snoopy
around at about 2 knots (estimated). The props are designed for
power, but that's what we want underwater. True, a kort nozzle
would increase that power but what is the return on the cost? In
other words, on a road with a speed limit of 30mph and no passing
zones it doesn't matter whether you have a 1.6 liter or 5.4 liter
engine under the hood does it?<br>
<br>
Like Vance, I don't want to rain on the parade and I do "get it"
that the challenge of coming up with a "home-built" alternative
can be rewarding. I just think that production cost will be the
determining factor on practical use. Like going from T-Rex back
to minn-kota, I can't help but wonder if the ultimate conclusion
will turn out to be that the stock minn-kota's are good enough for
99.99% of our applications.<br>
<br>
I can think of many things that your CAD experience could offer to
the group if you are interested in providing some designs. For
example the K350 plan modifications that have been talked about by
a few people. We could really use help in that area. <br>
<br>
Jon<br>
<br>
<br>
On 10/27/2013 6:20 PM, Joe Perkel wrote:<br>
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<blockquote
cite="mid:1382912430.33655.YahooMailNeo@web160504.mail.bf1.yahoo.com"
type="cite">
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<div style="RIGHT: auto"><span style="RIGHT: auto">Alec,</span></div>
<div style="RIGHT: auto"><span style="RIGHT: auto"></span> </div>
<div style="BACKGROUND-COLOR: transparent; FONT-STYLE: normal;
FONT-FAMILY: HelveticaNeue, Helvetica Neue, Helvetica, Arial,
Lucida Grande, sans-serif; COLOR: rgb(0,0,0); FONT-SIZE: 19px;
RIGHT: auto"><span style="RIGHT: auto">I've gone round and
round for the past two weeks in depth on the issues of
propulsion and have come full circle back to the trolling
motors. I was on hiatus for the discussion mentioned by
Vance ref contact with the manufacturer as I would have
remembered that.</span></div>
<div style="RIGHT: auto"><span style="RIGHT: auto"></span> </div>
<div style="BACKGROUND-COLOR: transparent; FONT-STYLE: normal;
FONT-FAMILY: HelveticaNeue, Helvetica Neue, Helvetica, Arial,
Lucida Grande, sans-serif; COLOR: rgb(0,0,0); FONT-SIZE: 19px;
RIGHT: auto"><span style="RIGHT: auto">So, I'm with you on the
prop and nozzle. While the 101's may indeed have <span
id="misspell-0"><span>plenty</span></span> of guts for the
job as is, the Kort data shows a 30% improvement in Bollard
thrust at low speeds for any given prop diameter. That and
the added benefit of protecting the prop, are significant
enough reasons to forge ahead. </span><span style="RIGHT:
auto">This is actually good news, less work by not mucking
around with the guts of the motor.</span></div>
<div style="RIGHT: auto"><span style="RIGHT: auto"></span> </div>
<div style="RIGHT: auto"><span style="RIGHT: auto">You guys are
the builders with recent hands on, I'm behind in the trial
and error business because I cant get started tinkering yet.
But as you well know, I developed CAD capability for this
purpose only, so time to put it to real use. Where I need
help is deciding on materials and manufacturing processes. I
can give you guys the cutting files needed to whittle a Kort
out of a block of solid titanium, but that would not be
practical. <span style="RIGHT: auto" id="misspell-0"><span>That's</span></span>
my limitation and where hands on <span style="RIGHT: auto"
id="misspell-2"><span>experience</span></span> counts.</span></div>
<div style="RIGHT: auto"><span style="RIGHT: auto"></span> </div>
<div style="BACKGROUND-COLOR: transparent; FONT-STYLE: normal;
FONT-FAMILY: HelveticaNeue, Helvetica Neue, Helvetica, Arial,
Lucida Grande, sans-serif; COLOR: rgb(0,0,0); FONT-SIZE: 19px;
RIGHT: auto"><span style="RIGHT: auto">Now these nozzles are
reverse foils with coordinates in percent of <span
id="misspell-1"><span>length</span></span>. I can generate
a NACA 4415 on my airfoil generator and transfer that to the
model. I can give us accurate 3d models and eventually CNC
cutting files for whatever the group wants on these Minn
Kotas, nozzles and attachment hardware. I can do both
Nozzles, Marin 19A, and or 37, with the latter being
optimized bi-directionally.</span></div>
<div style="RIGHT: auto"><span style="RIGHT: auto"></span> </div>
<div style="RIGHT: auto"><span style="RIGHT: auto">Finding
something off the shelf would be ideal, but I suspect given
the nature of the business and the quote I recieved it would
likely prove <span style="RIGHT: auto" id="misspell-4"><span>problematic</span></span>.</span></div>
<div style="RIGHT: auto"><span style="RIGHT: auto"></span> </div>
<div style="BACKGROUND-COLOR: transparent; FONT-STYLE: normal;
FONT-FAMILY: HelveticaNeue, Helvetica Neue, Helvetica, Arial,
Lucida Grande, sans-serif; COLOR: rgb(0,0,0); FONT-SIZE: 19px;
RIGHT: auto"><span style="RIGHT: auto">You need a new square
tip prop to optimize the duct. I've had custom props made
for my boat in the past, so that should not prove
insurmountable. I should be able to do the prop as well. </span></div>
<div style="BACKGROUND-COLOR: transparent; FONT-STYLE: normal;
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Lucida Grande, sans-serif; COLOR: rgb(0,0,0); FONT-SIZE: 19px;
RIGHT: auto"><span style="RIGHT: auto"></span> </div>
<div style="BACKGROUND-COLOR: transparent; FONT-STYLE: normal;
FONT-FAMILY: HelveticaNeue, Helvetica Neue, Helvetica, Arial,
Lucida Grande, sans-serif; COLOR: rgb(0,0,0); FONT-SIZE: 19px;
RIGHT: auto"><span style="RIGHT: auto">Can we post pictures on
this forum?, I forget. It would be helpful to point things
out. If I could post pictures of the various exploded
diagrams, I can point to where I want dimensions with red
arrows. Eventually, I'll start a web-page.</span></div>
<div style="RIGHT: auto"><span style="RIGHT: auto"></span> </div>
<div style="RIGHT: auto"><span style="RIGHT: auto">So for now, I
need some detail on the shaft and prop as is., what have you
done with that washer and where it is in the drive, as well
as any other modifications.</span></div>
<div style="RIGHT: auto"><span style="RIGHT: auto"></span> </div>
<div style="RIGHT: auto"><span style="RIGHT: auto">I think this
is a decent group effort project, and one that can pay
dividends in the end.</span></div>
<div style="RIGHT: auto"><span style="RIGHT: auto"></span> </div>
<div style="RIGHT: auto"><span style="RIGHT: auto">Joe</span></div>
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