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Hi Vance. Good advice.
On the rubber hose, I am planning on using a short HP hydraulic hose as a
union. I didn't want to use a regular plumbing type union as the fit-up is so
critical on those, and sometimes they leak. Now, if the rubber material is
no good to use, I could still use low cost NPT fittings but use a compression
coupler on each end where it mates with the hull stop valves. That way there's
no rubber in the line. Compression fittings for "gas service" would carry the
pressure and be fairly easy to replace if needed. I'm always trying to use parts
that a local hardware store might carry just in case I'm off somewhere remote
and need a replacement part.
On the air inlet, with a stainless 3/8" valve, it's a small risk being open
to the sea water, but it allows me to close off the internal piping. I just hope
that the 1" hull stop valves don't fail. As a redundancy I could add
another 1" stop valve between the hull and air line connection. I have the extra
room, and what's one more valve.
The low pressure rubber hose at the "ballast tank to thru-hull connection"
is needed to isolate the ballast tank electrically from the rest of the sub and
add a little flexibility to the connection. The ballast tanks are mounted so a
little movement is possible should I crash into something really hard. If
that little piece of rubber hose looks like it's going to hell, I can use a
vinyl hose or something that's not corrosive in salt water. It's low ( ambient)
pressure both inside and out, being open to the ballast tank. Mostly looking for
the break in electrical flow there to help prevent corrosion of the SS ballast
tank.
I've been watching for pure zinc scrap for anodes, but may have to just buy
some ready-made. I plan on putting them all over the place.
Frank D.
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