PVC for sanitation lines.

[JohnP]

I have changed permeated hoses on sanitation systems on most of my past boats. When I redid the holding tank on "Adagio" I decided to use as much sche 40* PVC as I could instead of hose. My thinking was it works in houses with out going bad*so it should work on a boat. *I installed rubber couplings to allow me to remove pieces if I ever had to service them. Most of this was off the shelf from a big box home store, for peanuts.** In service now two seasons with no issues at all.** Might be something that could work for some of you guys too.** Of course a single head 32'* IG sedan does have simple plumbing but it should work on a larger scale also.****

 

[Woodsong]

I would be curious if others have done this? The rubber fernco fittings should really help with making sure that you don't have glued fittings crack due to flexing but even then, I bet that glued fittings wouldn't crack. I have had a "slight" odor in the forward head that has caused me to contemplate line replacement.

 

[koliver]

black ABS pipe in mine, no cracks in the glued joints.

 

[hollywood8118]

I used to think that PVC/abs hard lines had do place in boats... but I started to accept them years ago after Steve Dashew advocated their use on boats... he used them on his Sundeer Yachts and I believe his " non sail boat" as he calls it still uses pvc. The p.o. of Volunteer plumbed the Exhaust from the MASSIVE water lift muffler to the counter under the stern with 4" abs.... I inspected it regularly and it never showed any signs of cracking/deterioration.... it ran about 25'. The boat had high exhaust water temp and low water flow alarms so I felt OK with it. Properly constructed and with room to allow flex with vibration and hull flex I think it is a great choice
HOLLYWOOD

 

[Woodsong]

The only reason I can think to not use PVC/ABS is to eliminate any and all joints that could fail and the ability to snake a hose around convoluted boat stuff in the bilge. If one has good access and can insulate the joints from flexing, etc. I would think it would hold up well too but I've not tried it in theory or reality.

 

[jleonard]

I used PVC to re make the long run from the aft head to the holding tank which is forward of midship. The original was also PVC.

 

[koliver]

A hard pipe will be better for a long run, as the soft pipe will sag and allow puddles to form. In a waste line, that can not be good.

 

[FF]

Old sailors that prefer the overkill of a repairable system should remember Series 80 PVC.

With a wooden plug shoved in to maintain shape while threading , this PVC can be threaded with std. plumbing tools,.

IT works fine as waste pipe and can take good pressure or suction.

We have 3 compartment subdivision (AKA watertight spaces) and use a clutched 2 inch engine driven Jabsco for de-watering.

With a extra thru hull its a fire hose , or great fun when the jet skis get frisky.

 

[HeadMistress]

koliver wrote:A hard pipe will be better for a long run, as the soft pipe will sag and allow puddles to form. In a waste line, that can not be good.

No...it's not. Which is why a long run of hose--any hose, not just sanitation hose--should be supported on hangers every few feet to eliminate the sags.

Hard pipe in sanitation systems is really only recommended for long straight runs, and it also needs to be supported every few feet.* It should also be "soft coupled" to anything rigid--toilet, thru-hull, tank, macerator pump etc--with enough hose to provide shock absorption...'cuz PVC becomes brittle enough in very cold weather that even a sharp rap against a dock can crack it.* So unless you have a long straight run, you're gonna have so many pipe-hose and other unions in it that there's really no advantage to hard pipe over permeation resistant hose.

Otoh, if it's not a sailboat and spends 90% of its time at the dock or cruising placid rivers and lakes,* you can get away with hard pipe no matter how convoluted the plumbing runs.* But I wouldn't advise it for boats that do trans ocean passages where it's not unusual to spend a day or longer in 10-15' seas.* I remember hearing from a boatyard owner in south FL who'd just gotten a 60' trawler in that had taken such beating in a storm coming from somewhere in the Caribbean that not only had the pvc piping cracked, but two fiberglass* tanks had as well!

*