Re: [PSUBS-MAILIST] Through Hulls

[Dan h <machine@epix.net>]

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