[PSUBS-MAILIST] thruster sizing etc

Sun Sep 28 07:38:44 EDT 2014

Hi Alan,

I am happy with the rotating thruster configuration on the Nordicsub boats.

Indeed you can double the power and you have a backup when the stern drive
fails.

When manoeuvring over the bottom , the thrusters are pointing about 45 deg.
Downward. As we dive the boat a little positive buoyant, you can push the
sub both forward and downward.

10 Kg thrust per Ton is a good rule of thumb value.. the Rotorque  thrusters
are still going strong after 100 op. hours and non maintenance.

Regards, Emile

  _____  

Van: Personal_Submersibles [mailto:personal_submersibles-bounces at psubs.org]
Namens Alan via Personal_Submersibles
Verzonden: zondag 28 september 2014 11:40
Aan: Personal Submersibles General Discussion
Onderwerp: Re: [PSUBS-MAILIST] thruster sizing etc

Thanks Alec that was helpful.

Is that the normal mode of operation, having the side thrusters locked

vertical? Were you putting them in reverse or just relying on positive
buoyancy.

I was planning on having side thrusters that are rotated by electric motors,
so my 

hands are just on a couple of joy sticks controlling all the motor
functions.

I liked the idea of using rotating side thrusters so that I could have
double the power travelling

horizontally if need be. Also there would be no need to ramp the motors down
to change 

from forward to reverse.

Any thoughts on the pros or cons of this anyone?

Alan

Sent from my iPad

On 28/09/2014, at 4:55 pm, Alec Smyth via Personal_Submersibles
<personal_submersibles at psubs.org> wrote:

Hi Alan,

On the stern, snoopy has a 55 lb Minnkota. The side thrusters are actually
of unknown thrust, they came with Snoopy and are Motorguides but I'm not
exactly sure which model. My estimate would be about 40 lbs (each). What you
saw in Florida would have been forward motion based on the stern thruster
alone, as I was using the side thrusters just for depth keeping, locked
vertical. The K250 has very limited battery capacity, carrying three
batteries in the standard design and four in Snoopy. I find the thrusters
well proportioned to the limited battery capacity. The bottom line is that a
K250 has perfectly adequate thrusters and batteries for diving, but not
enough for surface runs. Something in the league of Minnkota 101s is great,
but only on subs with battery pods.

Best,

Alec 

On Sat, Sep 27, 2014 at 8:17 AM, Alan via Personal_Submersibles
<personal_submersibles at psubs.org> wrote:

Alec,
what size motors do you have on Snoopy?
I remember watching you disappear into the blue surprisingly quickly in
Florida.
Were you using the stern & side thrusters simultaneously?
Are you happy with the speed?
I have spent a LOT of time Googling brushless motors & haven't come up with
an easy solution.
I was looking particularly at inrunner motors, as they have a couple of
advantages
over outrunners, however outrunners have lower revs. Whatever, they are both
going
to need gearing down majorly & matching up with a planetary gear isn't
looking easy.
Most of the motors that are available are found at Hobby King & are
lightweight & made
mainly for model planes. So their strength & ability to sustain several
hours of
continual operation are in question.
Must be a solution out there because 9 out of 10 thruster manufacturers are
using brushless motors & I doubt they would be making there own.
Alan

Sent from my iPad
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