[PSUBS-MAILIST] Mechanical Depth Gauges

[Douglas Suhr via Personal_Submersibles]

Ah, I think that would be great (to oil compensate the gauge).

It would be very cool to have a digital display that could be switched
from fresh to salt water. And though you are correct that I am young
Alan, I'm not too tech savvy. I've never even heard of Arduino before
- is that like Raspberry pie? 'Cause I've heard of this pie computer
and all I can think is, 'Yeah, I'll take a slice with some vanilla ice
cream please.' :) ~ Doug

On 7/30/18, Alan via Personal_Submersibles
<personal_submersibles at psubs.org> wrote:
> Doug,
> I am not sure how Snoopy's pressure gauge is set up but
> I know of at least one person that has a rubber solder sucker filled
> with oil screwed ( or attached) to the outside of the gauge port.
> The gauge then only sees oil not sea water.
> Gauges with electronic displays & the ability to flick between metric,
> imperial, psi, mpa etc are pretty cheap. I have a dwyer gauge ( somewhere).
>    Being a young person you may want to go down the route of buying
> a gauge that you can attach to an arduino, then electronically display on a
>
> board as big as you like! With a bit of code at the push of a button you
> could get it to display fresh or salt water depth.
> Cheers Alan
>
>
>
> Sent from my iPad
>
>> On 31/07/2018, at 6:36 AM, Douglas Suhr via Personal_Submersibles
>> <personal_submersibles at psubs.org> wrote:
>>
>> Ah, I think you're right Jon... because the gauge plate would not be
>> pressured anyway, huh. Never thought of that.
>>
>> No there was no gasket or anything, so I guess any moisture in the
>> viewing portion of the gauge would just come from moisture inside the
>> hull of the sub.
>>
>> And thank you for the pressures... not a huge difference but I suppose
>> at deep depths it could work out to be somewhat of an error.
>>
>> I wonder how Alec printed such a nice looking label(?). ~ Doug
>>
>> On 7/30/18, Jon Wallace via Personal_Submersibles
>> <personal_submersibles at psubs.org> wrote:
>>> Fresh water: .433psi per footSalt water: .445 psi per foot
>>> If there was no gasket sealing the acrylic/glass cover and bezel then
>>> it's
>>> likely condensation caused the wrinkling of the label.
>>> Jon
>>>
>>>      From: Douglas Suhr via Personal_Submersibles
>>> <personal_submersibles at psubs.org>
>>> To: Personal Submersibles General Discussion
>>> <personal_submersibles at psubs.org>
>>> Sent: Monday, July 30, 2018 1:16 PM
>>> Subject: [PSUBS-MAILIST] Mechanical Depth Gauges
>>>
>>> All, as you may've been aware, in late 2015 I purchased Snoopy (a
>>> K-250) from Alec Smyth. Regrettably I have been quite neglectful of
>>> performing much upkeep on the sub, save for keeping the batteries
>>> topped off. My schedule is finally allowing me to spend some real time
>>> working on the sub and getting to know the specifics of each system.
>>>
>>> As you can imagine, I've been bugging Alec with a question here and
>>> there, but thought with this topic I should start a discussion here on
>>> the list for the benefit of anyone else who might have questions /
>>> curiosities about mechanical depth gauges.
>>>
>>> Snoopy's depth gauge is nice and large (about 5" in diameter) so it's
>>> easy to read. Alec created a nice label for the gauge face which reads
>>> from 0 to 300 (in feet) with the last fifty feet being marked in red
>>> to indicate 'too deep.'
>>>
>>> Problem is, when I looked at the depth gauge the other day, I noticed
>>> that the transparent cover plate on the gauge looked to be quite
>>> opaque (to the point where I couldn't quite read the numbers or count
>>> the hash marks). I assumed that there was some moisture trapped in the
>>> gauge, causing the obscuration. I decided to remove the gauge from the
>>> sub and open it up to let it dry out.
>>>
>>> After removing the gauge from the sub, I unscrewed three small screws
>>> around the bezel and popped off the transparent cover plate. It was
>>> only then that I realized the opaqueness was not caused by moisture
>>> but a distortion in the clear plastic. The distortion (like super fine
>>> scratches) appears to be on the outside of the cover, as though it was
>>> cleaned by something that started to melt the plastic or was left out
>>> in the sun too long. I don't think either of these explanations make
>>> sense, but I'm puzzled as to what might have caused it. I might try to
>>> buff / polish the plastic, or perhaps just replace it with glass.
>>>
>>> I think it's a good idea to stick a dive computer in viewing range of
>>> a viewport for a depth reading, but I like the idea of having a
>>> mechanical gauge in the sub as well. A couple of questions that come
>>> to mind: what is the pressure variation between salt water and fresh
>>> water? Also, although I didn't find moisture in the gauge, The label
>>> on the face is wrinkled a bit as though it has seen moisture. Although
>>> water should never actually reach the gauge, I can see how moisture
>>> from the inlet tube could find its way up into the gauge body. Should
>>> I be concerned about drying it out somehow after a dive (especially in
>>> salt water)? If so, how should I go about it? ~ Doug S.
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