Is there any reason why black plastic piping should not be used to pipe
the waste system on a sailboat? Some flex is probably necessary but the
majority could be hard piped. Anyone done it successfully?
Tony

tbuck wrote:
Is there any reason why black plastic piping should not be used
to pipe the waste system on a sailboat? Some flex is probably necessary
but the majority could be hard piped. Anyone done it successfully?

Hard pipe is used quite a bit on large yachts, but it's not very
practical for use on the typical boat because it's not recommended for
anything except long straight runs, 'cuz anything else requires a bunch
of unions, all of which have to be cemented, and therefore a place for
a potential leak. It also has to be soft-coupled with about a foot hose
to anything in the system that's fixed or rigid--toilet, y-valve,
thru-hull, pump, tank--that acts a shock absorber and also absorbs flex
in heavy seas or lively tacking. In a system that doesn't have long
straight runs, that means a lot of connections, all of which are a
potential leaker AND places for waste, TP, and minerals to get stuck and
build up.


Peggie
----------
Peggie Hall
Specializing in marine sanitation since 1987
Author "Get Rid of Boat Odors - A Guide To Marine Sanitation Systems and
Other Sources of Aggravation and Odor"
http://shop.sailboatowners.com/detai...=400&group=327

http://www.seaworthy.com/html/get_ri...oat_odors.html

ABS makes good plumbing and can bend slightly - more if you "prebend" it
by bending it over a form for a couple weeks and letting it take a set
slowly. So it could likely be made to conform to some hull shapes. It
can be a messy PITA to glue up, but it's not rocket science to get it
right; but don't glue up in a small airless confined space or you'll
kill brain cells. Glue joints _can_ leak, but once you learn the
technique, it's extremelly rare.

ABS normally "dies" by cracking where the pipe enters a fitting.
Recurring mechanical or thermal stress with greatly hasten the end. I
have seen houses 25 years old with completely intact ABS drainage
systems. But I have also replace pipe in houses 5-15 years old which
cracked. Those mostly seemed cases related to a "bad brew" one major
manufacturer put out in middle 80's. ABS is presently accepted my most
cities and counties life expectancy is 30-50 years.

ABS does not tolerate UV, so it must be protected at least with a good
coat of paint if it gets any exposure at all.

It also doesn't like extreme heat and cold fluctuations. Eg. a drain
pipe for a standard dish washer which heats water to 140+F. will die
much sooner than the drain from the tub or even the kitchen sink, where
temperatures are only 105-110F. My first job as a plumber in San
Francisco was replacing all the ABS pipe under Green's restaraunt,
primarily because the commercial dishwashers they use dumped 160+F.
water down the drains 30-40 times a day.

The most likely problem would be securing it in a way the it does not
sag, but also so it can move slightly so it doesn't get flexed hard with
the movement of the boat's hull. Straps would ideally include 1/4"+ of
foam insulation around the pipe at the strap to allow this movement.
Although the pipe will take a bend easily enough, it doesn't want to
bend again and again. 1-1/2" pipe on a boat should probably be secured
not less then every 36" to prevent it whipping back and both when the
boat pounds. More strapping is almost alway better.

I wouldn't hesitate to use it if you are confident of your glue joints -
it can in theory help reduce the potential for odors in a boat. However,
Peggy is right about the need for a flexible connection at the fixture,
and it's also a good idea so you have an easy way to service the fixture
and get into that pipe if need be.

PVC drain pipe can withstand more temperature variation and can be had
with thicker walls thus increasing its stength. This might be a better
go. However, the glue joints are a little more of a problem, so be sure
you get some practice first.

Supply is pretty much the same story, only without the odor issue and
with the problem of holding pressure. Because hose works so well there,
I'd recommend you find some very large advantage to it before you bother
plumbing the supply in hard pipe.

Good luck. Rufus


Peggie Hall wrote:

tbuck wrote:
Is there any reason why black plastic piping should not be used
to pipe the waste system on a sailboat? Some flex is probably necessary
but the majority could be hard piped. Anyone done it successfully?

Hard pipe is used quite a bit on large yachts, but it's not very
practical for use on the typical boat because it's not recommended for
anything except long straight runs, 'cuz anything else requires a bunch
of unions, all of which have to be cemented, and therefore a place for
a potential leak. It also has to be soft-coupled with about a foot hose
to anything in the system that's fixed or rigid--toilet, y-valve,
thru-hull, pump, tank--that acts a shock absorber and also absorbs flex
in heavy seas or lively tacking. In a system that doesn't have long
straight runs, that means a lot of connections, all of which are a
potential leaker AND places for waste, TP, and minerals to get stuck and
build up.

Peggie
----------
Peggie Hall
Specializing in marine sanitation since 1987
Author "Get Rid of Boat Odors - A Guide To Marine Sanitation Systems and
Other Sources of Aggravation and Odor"
http://shop.sailboatowners.com/detai...=400&group=327

http://www.seaworthy.com/html/get_ri...oat_odors.html

Rufus wrote:
ABS makes good plumbing and can bend slightly - more if you "prebend" it
by bending it over a form for a couple weeks and letting it take a set
slowly. So it could likely be made to conform to some hull shapes.

More years ago than I want to admit, I was the marketing director for a
company that fabricated ABS and PVC underground and under-bridge conduit
for utilities...they bent a lot of pipe by heating it, then putting on a
form to cool, which was necessary to preserve the diameter around the
bend. So I'm assuming that unless you have the necessary form, any DIY
bending would have to be considerably less than even 45 degrees...maybe
even less than 15.

Peggie
----------
Peggie Hall
Specializing in marine sanitation since 1987
Author "Get Rid of Boat Odors - A Guide To Marine Sanitation Systems and
Other Sources of Aggravation and Odor"
http://www.seaworthy.com/html/get_ri...oat_odors.html

...any DIY
bending would have to be considerably less than even 45 degrees...maybe
even less than 15.

Peggie

Easily less than 15deg bend. Any bends close to that, use a fitting or
two. Dropping a pipe down the inside of the hull and over the "chine"
will almost certainly require fittings.

I was speaking only of the gentle bends that might enable a pipe to
follow fore/aft hull curvature in a small boat. ABS _wants_ to take a
sag or bend, and most pipe you buy will come with a ready-made "banana"
shape. Leaving a pipe suspended horizontally from it's ends with, say, 5
pounds in the middle, will yield a very boat like bend in a week or so.

The major advantage of hose is the ability to snake it through a path
without the need to rip stuff out of the way first; the secondary
advantage is not needing to assemble any fittings. However,
pre-assembled short pieces of piping with the needed bends can often be
installed the same way, as long as you're able to reach both ends and
continue plumbing, when the assembly is in place. You can also
man-handle ABS and bend it quite a bit to get it to go where you want.
If it's going to break in process, it will make a quite noticeable CRACK
that will alert you to your problem.

The disadvantage of hose is that it's relatively permeable and possibly
somewhat less physically tough than hard pipe.

Rufus

Speaking of which, what's the story with the gray plastic pipe that uses white
fittings? I don't see it anywhere except on my boat's potable water system.

John

Standard strength PVC water pipe is white. Double strentgh PVC water
pipe is dark grey. Light grey pipe is often thinwall stuff that is
designed for use as electrical conduit.

Rufus



Truelove39 wrote:

Speaking of which, what's the story with the gray plastic pipe that uses white
fittings? I don't see it anywhere except on my boat's potable water system.

John

Thanks for the answer, Rufus. But, I can't seem to find any of this pipe or the
white compression-type fittings anywhere. I'm told this stuff was "outlawed"
some years ago and is no longer available.

John


Standard strength PVC water pipe is white. Double strentgh PVC water
pipe is dark grey. Light grey pipe is often thinwall stuff that is
designed for use as electrical conduit.

They have lots of that at a local hardware store, here in Kemah, TX. It's
still being made, you'll just have to dig deeper to find it where you live.
It should be available on the web as well if you can't find it locally.

"Truelove39" wrote in message
...
Thanks for the answer, Rufus. But, I can't seem to find any of this pipe
or the
white compression-type fittings anywhere. I'm told this stuff was
"outlawed"
some years ago and is no longer available.

John


Standard strength PVC water pipe is white. Double strentgh PVC water
pipe is dark grey. Light grey pipe is often thinwall stuff that is
designed for use as electrical conduit.

Local stores here in Va have lot's of it, and cheap too. I just bought
enough 1" white to make an awning support.

Keith wrote:

They have lots of that at a local hardware store, here in Kemah, TX. It's
still being made, you'll just have to dig deeper to find it where you live.
It should be available on the web as well if you can't find it locally.

"Truelove39" wrote in message
...
Thanks for the answer, Rufus. But, I can't seem to find any of this pipe or the
white compression-type fittings anywhere. I'm told this stuff was "outlawed"
some years ago and is no longer available.