On May 17, 11:38 pm, Don W
wrote:
RW Salnick wrote:
I'd skip the use of the head hose, except as for flexible connections to
hard-mounted items, unless the runs are very short. Instead, plumb with
rigid white PVC pipe - it has an essentially infinite permeation time -
unlike the hose.
bob
s/v Eolian
Seattle
Hi Bob,
I'd love to plumb with PVC pipe, but I've heard
that the flexing of the boat causes it to develop
cracks over time. Is that true?
Don W.
Hi, Don, and group,
I'm not an expert, but I can provide some RW experience.
Most of you know that I had about the most boat flexing one can
experience and still float, after it's over, a few months ago.
Before that time I had installed PVC exhaust plumbing on both heads.
The forward head, which I'd originally thought would be impossible,
turned out to be feasible with lots of joints, and some creative
vocabulary. The aft, which I originally thought would be a piece of
cake, I then thought couldn't be done at all, actually turned out
pretty simple.
However, I learned a bit along the way. As nobody's going to be
grading you on neatness, slop the crap (pardon the expression) out of
the joints with cleaner, and then with the glue, when you're making
the assembly (do it all dry first, of course, and allow for the full
depth of insertion as the glue will act as a lubricant, letting you
seat it fully where it won't go, dry).
I didn't do that in my forward head installation. As a result, I had
two very minor seeps at two joints after the incident (more below).
Those were cured with careful sanding and addition of, first, more
glue preceded by an acetone wipe (to clean and soften the plastic),
and followed by some penetrating epoxy (more flexible than laminating
or general-purpose epoxy) with a thickener added to keep it in place.
As I'm currently on the hard, I shut the thru-hull connection, opened
the anti-siphon valve (like you'd see in a laundry connection), and
poured water into the system until it was full (both toilet and hull
ends of the line), and waited a week. No seeps. The aft didn't leak
anywhere.
So, from that, I get...
First, if you think you're being ridiculous in your application of
cleaner and glue, and follow up each joint with swabs around the
perimeter for good measure, it's unlikely you'll ever have a leak.
Second, if there *is* a very small leak, it can be addressed, if you
can get to it. I'd originally thought I'd have to cut out the
offending joint - but even that's possible to do.
Meanwhile, as an establishment of the bona fides of this process, this
hard pipe stood up to huge hull flexing and pounding (impacts) - more
than you'll ever encounter in normal seagoing life. As seen in my
"Thanksgiving" post, I estimate, based on time and wave interval, that
our hull took not less than 3000 and probably more than 5000 huge
crashes on rock. The flexing our hull provided in her defense is
totally awesome, and for which we're without words to adequately
express how grateful we are that was so. From that I can provide my
own assurances that, done right (joints fully glued) and supported (no
flailing around) that it's unlikely you'll ever have to deal with that
again.
Given the stench of the hose we took out (the good stuff), I'm very
happy to not have to face that thought in this boat's lifetime.
Meanwhile, I have the 15' of AVS96 that I bought to do the forward
head available, now (after the wreck, I'm sure I won't need it),
should anyone want it.
And, finally (you knew I'd get here, eventually, right??), for those
so inclined, my galleries have the gory details on the installations
of both heads' hard pipe, and I can give you the links if you like.
However, in general, I think the forward head (the more complex of the
two) was Feb06 in the refit gallery.
Hope that helps...
L8R
Skip
Morgan 461 #2
SV Flying Pig KI4MPC
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