[Date Prev][Date Next]
[Chronological]
[Thread]
[Top]
Re: [PSUBS-MAILIST] Which Through-Hull?
Thanks, Phil. Just to translate, plasticine is British Columbian for
modeling clay? Does the same approach work with Aluminium? How often do
you repeat the pressure test?
Joe, not Shin
----- Original Message -----
From: Phil Nuytten <72020.572@compuserve.com>
To: <personal_submersibles@psubs.org>
Sent: Sunday, July 29, 2001 5:20 PM
Subject: Re: [PSUBS-MAILIST] Which Through-Hull?
> Hi, Shin:
> What are you going to screw your proposed penetrators into? That
> is, will you weld in a threaded boss or weldelet (a short piece of
> cylindrical, heavy-wall pipe, threaded internally, that is pushed into a
> hole in the hull until it protrudes equally,and then welded inside and out
> - or a threaded, contoured coupling that is welded on the outside only) or
> will you weld in a smooth bore cylinder so you can use threaded fittings
> with 'o' ring collars and a retaining nut inside? If you decide on a
> threaded boss ( as most garage subs do) make sure that it is stainless
> steel ( welds easily to mild steel) and has a very thick wall so that you
> can drill it and tap it to the next largest thread size if you ever have
to
> . .for example, if you want to have a threaded hole that actually measures
> 1/2" in diameter ( like 1/4" NPT ) then the boss should not be less than
1"
> in diameter - while 11/4" is better - an so on for larger sizes. The cost
> of these, even custom made, is small compared to having to deal with a
> rusted out or stripped penetrator down the road.
> For electrical thru' - hulls, take a double male pipe fitting -
> with a center hex wrench flat - either brass or stainless, and of a size
so
> that the male screws into your hull penetrator boss. Take an appropriate
> tap and cut some threads on the inside smoth bore of the double male
> connector ( doesn't have to be full depth threads - nothing will be
screwed
> in here)Get two or three long - at least 2" or 3" - thin - say 6/32 or
> smaller - brass machine bolts and cut the heads off and dress the cut
ends.
> Get or make a female reducer coupling whose minor diameter will screw onto
> the other end or your male connector ( the end that will not be screwed
> into the hull boss.) and whose large bore is sufficient to take your cable
> jacket with a 1/8th to 3/16th gap all round. Poke the bolts thru until
they
> protrude sufficiently to be able to solder onto( this will be the hull
> interior), then space them equi-distant in the coupling bore ( use a thin
> plexi or other plastic pre-drilled disc as a template/spacer) cover the
> spacer disk and the bolt ends with a ball of plasticine, being careful
that
> the disc doesn't shift. On the other end you have soldered the two or
> three wires of a length of cabtire (neoprene jacketted multi-conductor
wire
> - like heavy-duty extension cord) Clean the jacket after lightly sanding -
> acetone or toluene) make sure at least 11/2" of jacket is inside the
female
> connector - pour the connectors full of two component, general purpose
> rigid epoxy that has been heated to make it pour easily . .you can use
two
> component polyurethane such as 3M 'Scotchcast' - it will bond to the
> neoprene jacket well, but that flexible bond is not a requirement since
the
> portion of the cabtire in the connector sleeve cant flex, Properly done,
> these are good to several thousand feet and are fully water-blocked if you
> should damage the cable ( the water cant wick thru the solid bolts as it
> would thru the multi-strand wires of a compression fitting) . Sounds like
> lot of work - but pretty easy once you have it down pat and are making up
a
> bunch at a time. Be sure to pressure test each on by threading it into a
> suitable 'T' - pressure gauge in one of the two remaining females, air
> fitting in other - point it away when you first pressure up.
> Beats paying a hundred bucks+ a pop for tested thru-hulls. These should be
> around ten bucks apiece.
> Sorry to be so long- winded - but with no napkin to draw on . . .
> Phil Nuytten
>