[PSUBS-MAILIST] Rotary Seal

[Alan via Personal_Submersibles]

Hi Hank,
the high rpm is because of the brushless motors I'm wanting to use.
I don't want to use a gearbox because of added expense, power loss,
noise, maintenance & risk of failure. I did look for a gear box initially but
couldn't find a suitable candidate. Looking at other commercial thrusters
I saw that they went up to 3000rpm, so have bought bigger BLDC motors
that are slower revving & are going to use them at about half their capacity 
to keep below this.
I have one motor & 2 on the way & will do a bit of experimentation with
the revs & different props. Fortunately you can test these in water as is,
so I don't need a can for each option. 
I am also looking at the motor canister & seal options though.
Alan



Sent from my iPad

> On 3/12/2014, at 2:33 am, hank pronk via Personal_Submersibles <personal_submersibles at psubs.org> wrote:
> 
> 
> Alan,
> That is an interesting idea, to reverse them.  What happens when there is no internal pressure, maybe nothing.  You would have to look at them closely to decide.  It has been so long since I saw one, but I think it is a simple wiper seal.  I have one apart, I can check it out.  I think that high rpm is going to haunt you.  I thought low rpm and big prop was the most efficient.  
> Hank
> --------------------------------------------
> On Mon, 12/1/14, Alan James via Personal_Submersibles <personal_submersibles at psubs.org> wrote:
> 
> Subject: Re: [PSUBS-MAILIST] Rotary Seal
> To: "Personal Submersibles General Discussion" <personal_submersibles at psubs.org>
> Received: Monday, December 1, 2014, 9:32 PM
> 
> Hank,what seals
> do trolling motors use?Would I be
> better to mount them the other way round, as I have a 4psi
> internal overpressure?Alan
> 
> 
> 
> 
>    From: hank pronk via
> Personal_Submersibles
> <personal_submersibles at psubs.org>
> 
> To: Personal
> Submersibles General Discussion
> <personal_submersibles at psubs.org> 
> 
> Sent: Tuesday,
> December 2, 2014 2:54 PM
>  Subject: Re:
> [PSUBS-MAILIST] Rotary Seal
> 
> 
> Alan,
> It seems that trolling
> motor seals work pretty good, what about them.  Are you
> planning a high rpm?  
> Hank
> --------------------------------------------
> On Mon, 12/1/14, Alan James via
> Personal_Submersibles <personal_submersibles at psubs.org>
> wrote:
> 
> 
> 
>  Subject:
> [PSUBS-MAILIST] Rotary Seal
>  To:
> "Personal Submersibles General Discussion" <personal_submersibles at psubs.org>
>  Received: Monday, December 1, 2014, 8:44 PM
> 
>  Has anybody got any
> recomendations on a rotary
>  seal type for
> my thruster propeller shaft. Looked at the Parker
>  seal pdf & there seems a lot of options.I
> am wanting to oil compensate using the 3 cst
>  silicone oil that Carsten recomended,&
> intend to have about 4 psi internal pressure
>  above ambient.ThanksAlan
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