Why not pex everywhere?

[Woodstock]

As Portage_Bay mentioned, the trap in a house drain is to block sewer gas from coming back up the drain. No such problem on a boat where the drain goes right over the side, so no reason to have a trap. And no traps means the drains are harder to clog as well.

I have a situation that has me considering a P trap in our forward VIP sink. The outlet for the sink is just inches away from two holding tank vent lines. There were many times the past couple years that we noticed smells coming back up through this sink and I'm now convinced that it's the holding tank vapors drifting back up the sink outlet.

 

[Comodave]

I have a situation that has me considering a P trap in our forward VIP sink. The outlet for the sink is just inches away from two holding tank vent lines. There were many times the past couple years that we noticed smells coming back up through this sink and I'm now convinced that it's the holding tank vapors drifting back up the sink outlet.

Be worth a try. Let us know how it goes.

 

[twistedtree]

I have found 2 types of corrugated hose:
On the bilge pumps, as originally found aboard, the corrugated hose is quite thin, no more than 1mm wall, with corrugations that are ~3mm, so present on both inside and outside, with a smooth portion ~ every foot, to allow clamping to the pump and the thru-hull fitting. This is cheap and ubiquitous.
I have changed out the thin, cheap stuff for a proper, smooth hose 1" diameter to match the output fitting on the bilge pumps. My dinghy pump is smaller, and the run is short, so it has the small corrugated stuff.

In other locations, a larger diameter hose has "corrugations" on its whole length, but a smooth interior surface. No clamping spots present or required.

I'm thinking of the second type. I agree the first type is garbage.

 

[rslifkin]

I have a situation that has me considering a P trap in our forward VIP sink. The outlet for the sink is just inches away from two holding tank vent lines. There were many times the past couple years that we noticed smells coming back up through this sink and I'm now convinced that it's the holding tank vapors drifting back up the sink outlet.

Good thought. I keep my aft head sink drain plugged when not using it. It gets generator fumes blown back up the drain in certain conditions, so a trap would likely help.

 

[Bmarler]

I have a situation that has me considering a P trap in our forward VIP sink. The outlet for the sink is just inches away from two holding tank vent lines. There were many times the past couple years that we noticed smells coming back up through this sink and I'm now convinced that it's the holding tank vapors drifting back up the sink outlet.

There’s no good reason you can’t use a trap. I did on my last boat at the galley sink. It was actually the easiest way to plumb the drain for the double basin sink.
The 1-1/2 sanitation hose slides right over the standard kitchen sink trap plumbing. Obviously you only want to use this above waterline.

 

[Capt8888]

On my kitchen sink I just curved the drain hose upwards 2" or so and then down to the waterline thru hull. Effectively a "P" trap. Quietens the wave slapping completely and works perfectly over 5 years!

 

[stubones99]

PEX is not UV stable, so keep it out of the sun!

No PEX tubing is rated for use when sun or other UV sources can damage it... It gets brittle quickly with UV exposure.

If you want to bend pex in unique shapes, use pex al pex products which is a layer of aluminum tubing with pex on the inside and outside. That lets you route it wherever you want and the bends stay where you put them.

 

[ronobrien]

My 2001 Mainship 390 has pex tubing, but from the factory came with the compression-screw on fittings that are all being replaced as I come across them with crimped connectors or shark-bite style if I’m unable to crimp something. As I’ve been doing this and staring at other various hoses I’ve been wondering, why not pex tubing and connectors more places?

I’m not advocating replacing anything like through hull water intake hose, I’ll stick with the marine water hardwall hose for that stuff.

What about all the super cheap corrugated type bilge discharge hose? They used the same stuff on most sink and any other type of drain I come across.

I also noticed my supply connections for the A/C-heat units are cheaper hose. I know most will say not skimp there and I agree, but I’ve thought about it.

Some places may be more challenging with bends and turns, and I’m not fond of adding connectors in any spot I can’t easily monitor. I’ve heard there is something called “flexi-pex” that may handle bends better.

I’d be curious about your thoughts on this. Thank you!

I am refitting a boat now and I intend to use PEX on all the fresh water plumbing, but I don't think that I would want it on anything with raw water or for any other mechanical purpose.

 

[psneeld]

I used pex with the nylon fittings for my raw water washdown system and plumbing to the toilets. Used the clear/white tubing instead of red/blue.

Thought about it for my A/C system cooling water, just didn't wind up using it...don't see why I couldn't have as it is never under much pressure and the crimps seem to last as long as many of the hose clamps for the vinyl tubing I did use.

 

[ronobrien]

I used pex with the nylon fittings for my raw water washdown system and plumbing to the toilets. Used the clear/white tubing instead of red/blue.

Thought about it for my A/C system cooling water, just didn't wind up using it...don't see why I couldn't have as it is never under much pressure and the crimps seem to last as long as many of the hose clamps for the vinyl tubing I did use.

I hadn't thought of the nylon fittings. Good idea.

 

[Cartouche]

My 2001 Mainship 390 has pex tubing, but from the factory came with the compression-screw on fittings that are all being replaced as I come across them with crimped connectors or shark-bite style if I’m unable to crimp something. As I’ve been doing this and staring at other various hoses I’ve been wondering, why not pex tubing and connectors more places?

I’m not advocating replacing anything like through hull water intake hose, I’ll stick with the marine water hardwall hose for that stuff.

What about all the super cheap corrugated type bilge discharge hose? They used the same stuff on most sink and any other type of drain I come across.

I also noticed my supply connections for the A/C-heat units are cheaper hose. I know most will say not skimp there and I agree, but I’ve thought about it.

Some places may be more challenging with bends and turns, and I’m not fond of adding connectors in any spot I can’t easily monitor. I’ve heard there is something called “flexi-pex” that may handle bends better.

I’d be curious about your thoughts on this. Thank you!

It's not pex if the fittings are Black they are 15mm and if white they are 1/2"
https://www.marineoutfitters.ca/index.cfm?category=10036|10692|11370 Pex will not fit and the sea tech fittings come apart real easy

 

[koliver]

I am refitting a boat now and I intend to use PEX on all the fresh water plumbing, but I don't think that I would want it on anything with raw water or for any other mechanical purpose.

I replaced the original grey plastic, the stuff that was taken off the market one or two decades ago, with pex, for my anchor washdown system. It is exposed to UV and is for raw (salt) water only. Now 4 or 5 years in, it has performed flawlessly and still looks like new. If it is degrading, I can't find evidence of that. If it fails, I will replace it with....Pex, as it is the easiest to work with, by far, and does the job well.

I guess my experience doesnt count for much, since, here in SW BC we don't get UV except for 2 days in summer. I think those occurred Monday and the Friday before.