Re: [PSUBS-MAILIST] Through Hulls

["Walter Starck" <wstarck@ozemail.com.au>]

Dan,

This isn't theory.  I have used hundreds of such connectors over many
years in a wide range of applications.  I also manufactured  and sold
several thousand of them..They do work and cable extrusion is not a
problem in depths of 1000 feet or less.  Make one up and test it.  You
don't need a chamber to test for extrusion.  A weight suspended from the
cable will do.

Walter Starck
Golden Dolphin Video CD Magazine
The premiere publication of diving and the ocean world.
www.goldendolphin.com


 ----- Original Message -----
From: "Dan h" <machine@epix.net>
To: <personal_submersibles@psubs.org>
Sent: Friday, November 22, 2002 1:03 PM
Subject: Re: [PSUBS-MAILIST] Through Hulls


> Thanks a lot Walter
>
> I didn't think capturing the jacket of a cable like that would be
enough to
> keep it secure at that kind of depth.  I was planning to epoxy each
> conductor of my cable separately to ensure it wouldn't slide through
and/or
> leak.  My way is far more complicated and doesn't really keep water
from
> getting into the cable jacket.  I'll make a test piece with your
method in a
> few days.
>
> Thanks again!
> Dan H.
>
> Walter Starck wrote:
>
> > Dan h wrote:
> > " A description of how you design your through hull electrical
> >  connectors, what type of cable is better and for what reasons would
be
> >  vary helpful to many of us in here.  This would be of far more use
to
> > us
> >  amateurs.   Please describe how you recommend building an
electrical
> >  through hull."
> >
> > The following is for a continous (i.e. non-disconnectable) thru hull
> > fitting.
> >
> > Start with a male NPT to metal tube flare fitting for tubing of the
same
> > size as the cable to be used. Remove the flare nut, face off the
nipple
> > in a lathe and bevel the resulting face at 45° sloping inward.  The
i.d.
> > of the fitting can be bored out slightly if required to accept the
> > cable.
> >
> > Use cable in which the insulated conductors are embedded in a solid
> > outer casing.  The common type that uses a fiber filler inside a
tubular
> > outer cover should be avoided.  To effect a seal, pass the cable
through
> > the original flare nut, followed by two O-rings, then the modified
> > fitting.  When the nut is tightned the O-rings are compressed inward
by
> > the beveled inner face of the nut and by the inward sloping face on
the
> > modified fitting.  This compression squeezes the O-rings into the
outer
> > cable covering creating an annular depression and locking the cable
in
> > place with a very effective watertight seal.  For use in depths of a
> > thousand feet or less this type of fitting is cheap, robust, easy to
> > make and highly reliable.  The fitting is of course used by drilling
and
> > tapping to install it where required.  Depending upon thickness and
> > curvature of the hull a flat boss may be required for attachment.
> >
> > Disconnectable through hull fittings are somewhat more complicated
but
> > can also be made using the same cable sealing method but more
complex
> > machine work is required as both plug and receptacle fittings must
be
> > fabricated from bar stock.  They are joined with a pipe coupling nut
> > with O-ring seal  and employ an internal electrical connector for
that
> > connectivity.
> >
> > Walter Starck
> > Golden Dolphin Video CD Magazine
> > The premiere publication of diving and the ocean world.
> > www.goldendolphin.com
>
>