[PSUBS-MAILIST] thruster sizing etc

[Alec Smyth via Personal_Submersibles]

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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