[PSUBS-MAILIST] Water jets

[hank pronk via Personal_Submersibles]

Mark,
I have coffee with a neat old guy that has a aluminum jet boat with 1,000 hp and goes 130 mph that does not sound efficient. :-)
Hank --------------------------------------------
On Sun, 10/26/14, Marc de Piolenc via Personal_Submersibles <personal_submersibles at psubs.org> wrote:

 Subject: [PSUBS-MAILIST] Water jets
 To: "Personal Submersibles General Discussion" <personal_submersibles at psubs.org>
 Received: Sunday, October 26, 2014, 10:11 AM
 
 There is nothing
 inherently inefficient about waterjets. There are 
 commercial fast ferries using them and getting
 very good thrust per 
 horsepower - better
 than any supercavitating propeller could do at the 
 same speed, certainly.
 
 Lousy design will of course produce poor
 results, and jets are much less 
 amenable to
 rule-of-thumb construction than open propellers. But whether
 
 it is "well known" or not, good
 design will produce good results.
 
 Marc de Piolenc
 
 On 10/26/2014 8:41 PM, hank pronk via
 Personal_Submersibles wrote:
 >
 > Graham,
 > In the world
 of marine jet drive it is well known that jet drive takes
 two times the horse power to do the same job.  Jet drive is
 well suited to a craft that needs a shallow draft.  I think
 you will find it very complicated to control and it will be
 very inefficient. I have been down this road, I love the
 concept but abandoned it.  If you go forward may I suggest
 you start with a jet drive.  It is not a simple part to
 replicate.  The impeller tolerances are critical.  I have
 a jet unit on the shelf I could donate to your project. 
 The jet is from a jet ski. I would consider a single rear
 motor on a full gimbal.
 > Hank
 --------------------------------------------
 > On Sun, 10/26/14, Graham Bayliss via
 Personal_Submersibles <personal_submersibles at psubs.org>
 wrote:
 >
 >   Subject: [PSUBS-MAILIST] (no
 subject)
 >   To:
 "'Personal Submersibles General
 Discussion'" <personal_submersibles at psubs.org>
 >   Received: Sunday, October 26,
 2014, 7:39 AM
 >
 >   #yiv9417249292
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 Hi   I am near the end of my build
 >   of my k350 and have started
 to look at new designs I am
 >   interested in building a
 flyer sub and have come up with a
 >   design which will include a
 vectored motor drive this will
 >   enable my flyer to hover and
 stop where ever I want. I have
 >   designed a motor unit which
 will drive a fan type propeller
 >   as an intake this will force
 water to the rear of the unit
 >   
 where it is compressed  then it is forced into ducting
 >   which will take  the water
 to four nozzles on the side of
 >   the craft. The nozzles are
 able to turn three hundred and
 >   sixty degrees  both side are
 independent of one another so
 >   rolls will be achievable. The
 reason for a vectored motor is
 >   you only need one motor
 source and one power pack this will
 >   ease the maintenance and
 increase the enjoyment of using
 >   your sub. I am interested in
 the clubs thought of this kind
 >   of design.  Graham
 >
 >   -----Inline Attachment
 Follows-----
 >
 >   _______________________________________________
 >   Personal_Submersibles mailing
 list
 >   Personal_Submersibles at psubs.org
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 >
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 >
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 > Personal_Submersibles at psubs.org
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 >
 
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