[chbot] Building a Sea Pearch ROV

[Mark Beckett]

Kerry
Have you seen what they do it on the underwater scooters.
These are designed to be immersised, and don't seem to use an air line 
to keep the water out.
Fresh water usually isn't an issue, as submersible water pumps use the 
water flowing around the commutator to cool it.
Even the submersible ones in petrol tanks use the liquid to cool.

For saltwater (and chlorinated) it might be enough to flush with running 
water, which could utilise a fitting or device to force the water through.

The glands on yachts aren't usually required to deal with any sort of 
depth, however 10m is 1 bar (14.8psi) more than the the surface.

Mark

Richard Jones wrote:
> Traditional yachts use a stern gland to seal the prop shaft. Here is a
> diagram: http://www.sea-dreamer.com/subject_page.asp?subject=Stern%20Gland&pagename=2
> I have a tub of waterproof grease that I use to seal the stern gland
> and I could let you have a little blob. But I suspect vaseline will be
> about as good and more friendly to youngsters.
>
> Richard
>
> On Sat, Oct 1, 2011 at 11:51 AM, Kay edgecumbe <kayedgecumbe at hotmail.com> wrote:
>   
>> one of the tricks i use for air pump on my sub was to use the servo arm to
>> start the pump and at the same time the back of the servo arm released the
>> kink in the air hose so that the air trapped in the rise fall ballast only
>> flowed if the motor pump was activated ---very reliable
>>
>>     
>>> Date: Fri, 30 Sep 2011 17:03:02 -0500
>>> From: kerry at manukadesign.co.nz
>>> To: chchrobotics at lists.linuxnut.co.nz
>>> Subject: Re: [chbot] Building a Sea Pearch ROV
>>>
>>>
>>>
>>> Quoting Mark Beckett <m.beckett at amuri.net>:
>>>
>>>       
>>>> Looks like a great idea.
>>>> Hadn't thought of sealing a motor in wax.
>>>>
>>>> Do you have access to Cat 5 patch cable (its more flexible than
>>>> ordinary single strand)?
>>>> I'm picking a couple of 20m lengths should be enough.
>>>>
>>>>
>>>> Mark
>>>>
>>>>         
>>> Yeah using wax just seems too simple. I would be interested in finding
>>> out what sort of depth you could get these down to before you get
>>> water leakage. In older designs they used a layer of vaseline at the
>>> shaft end of the motor then an epoxy to seal the rest.
>>>
>>> I work for Molten Media so lengths of patch cable are no problem. Yeah
>>> I was assuming two cables the first one for controlling the 3 motors
>>> and the other plus the two extra strands from the first for any other
>>> things like cameras, light, etc.
>>>
>>> What got me onto this project in the first place was talking with Mark
>>> Atherton about building an electric fishing torpedo - like this:
>>> http://fishingtorpedo.co.nz/company.html without spending the better
>>> part of $1200 to $1400, and I was having some trouble getting my head
>>> around sealing the prop, he lent me a book on diy rov's which included
>>> the Sea Pearch which seemed like a great testbed for larger rov's or a
>>> fishing torpedo.
>>>
>>> Kerry
>>>
>>>
>>>
>>>
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>>     
>
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