I'll attempt to summarize and respond to the various discussion items in one post. To summarize, of course there will be applications for all sorts of additional or different connectors for thrusters, lights, more advanced sonars, etc. All we are trying to standardize on here, however, is a basic connector for communications. Let's keep it simple. We just want to be able to communicate with or between PSUBS and if someone wants a sonar array, video cameras, etc. those simply go through whatever connectors they want to use. Those things are beyond the scope of this proposed standard.
OK, I'll summarize.
1. What thread is it?
I just called Subconn to confirm, it is 7/16" x 20 UNF
2. Is there an off the shelf pipe coupling to screw into?
Not that I'm aware of, because this is a parallel thread whereas most pipe couplings use tapered threads. I did locate some straight thread fittings on McMaster. However they are not stainless and the diameter is insufficient for the o-ring seat. It is really simple to make your own. Just drill and tap a piece of 1" 316 round stock long enough to go through your hull and take a fillet weld on each side. If you want a more flexible yet harder-to-make solution, use a removable bulkhead. See the fifth photo from the top on my Snoopy project page for an example. If anyone wants the drawings for those, I'm happy to supply them. If anyone has a source of off-the-shelf female-threaded, thick-walled little cylinders in 316 of course let us know.
3. Can we accomodate different pin count connectors using the same hole?
The connectors with 2 through 5 contacts use the same thread (I didn't pick the 5 contact conductor because it's current capacity is too low for some of David's equipment). Beyond 5 conductors, the thread size increases so you would need a different hole. I don't think there's enough difference in diameters for an adapter. Plus, as these are parallel threads you would need an o-ring in the adapter, which complicates it a little. Off the shelf pipe adapters won't work due to their tapered threads. So... if you need additional connectors use either a multi-connector removeable bulkhead, or weld in a variety of threaded cylinders and screw blanks into the spares.
4. Merits of plastic vs. metal
I have used both types for years. I agree with Vance's preference for metal, because I recently broke one of my plastic connectors. I'll admit it was purely my fault, I over-tightened it with a wrench when one is only supposed to hand-tighten only. Metal connectors like this one are less exposed to my stupidity. The one thing I disagree with Vance on is that plastic ones are dirt cheap. They were when I bought them years ago, but now I was quoted higher prices for those than for this one.
5. Need to agree on pin assignments, not just connectors
Excellent point. Let's make an executive decision: black and white for comms transducer, red and green for hydrophone. Unless I'm mistaken, polarity doesn't matter in either case so it's just the pair assignment that counts.
6. Don't we need 4 pins for comms?
No, I don't believe this applies. My assumption is that our comms are wireless. Wireless comms use the same transducer for both ingoing and outgoing signals. So long as we are on the same frequency, all divers and subs can hear each others' conversations. We should agree on a frequency, but that's immaterial to the connector choice. BTW Divelink is single frequency, but OTS has a choice of several. As I understand it, one of the OTS channels coincides with Divelink, so we should all be able to converse if we adopt that one.
7. Is this ABS certifiable?
I'm not sure what ABS requirements are for certifying connectors. I do know however that this particular product line is Subconn's oldest and has been around for decades. It is surely used on certified subs.
8. What size is the O ring?
It's 1/2" ID, 5/8" OD. In other words, the seat for the connector has to be larger than 5/8".
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From: owner-personal_submersibles@psubs.org [mailto:owner-personal_submersibles@psubs.org] On Behalf Of ShellyDalg@aol.com
Sent: Friday, December 18, 2009 10:43 AM
To: personal_submersibles@psubs.org
Subject: Re: [PSUBS-MAILIST] RFC - Standard Thru-Hull Electrical Connector
Boy, I had a feeling this would get more complicated.
The additional ideas all sound pretty reasonable to me, and standardization will be necessary if we want to plug in a radio for the convention.
I don't think anyone wants to spend $50K doing it though.
Lets try to keep this simple.
As a minimum standard for this application, all we really need is "what size is the welded coupling" and we can screw what ever comes along into it.
If we don't use it, it just gets a hard plug with pookie.
I would suggest we make the coupling big enough to accomodate a multi pin plug. I favor a 1 inch coupling size only because it would be large enough to accept mostly any size. It's easy enough to add a reducer bushing into it and still leave enough room for multiple pins.
The proposed Subcon part looks fine for the convention radio, and even has two extra pins.
As for ABS cert.........much like what we already use as guidelines, it doesn't need to pass any tests but just be "up to the standards" of ABS.