I'm thinking ahead to the raw water plumbing for the self-contained AC units I'll install in my Chris Craft Roamer refit and am hoping for some suggestions. Since this is an aluminum boat, I'm minimizing copper and bronze inside the boat as much as possible. So even though I've got tons of bronze plumbing bits from previous boats, I want to avoid using it in the Roamer.
My seacocks will be Marelon, as are the tailpieces/hose barbs. But Forespar doesn't make plumbing parts that I can fashion into a manifold to split the raw water supply from 1" to three 5/8" hose barbs. PVC is out of the question (I think) even though the manifold will be above the waterline. I could weld up something out of stainless tube, but if there's something off the shelf, that'd probably be my preference.
Thoughts?
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07-12-2022 03:47 PM #1Senior Member
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What do you use for an AC raw water manifold?
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Re: What do you use for an AC raw water manifold?
What's wrong with PVC?
Photo is from an 80' Weaver, they are pumping seawater thru the entire boat to individual self contained AC units.
Weaver 80 AC manifold.jpgCRICKET
1966 HAT50C101
Purchased 1985 12v71Ns
Repowered 1989 with 8v92TI
Repowered 2001 with 3406E
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Re: What do you use for an AC raw water manifold?
This is the setup I have onboard Katerina, except only 4 valves. Works perfectly.
The manifold IS above the waterline and has a standard rubber hose from the March TE-7 seawater pump to the manifold.Last edited by zigzag930; 07-12-2022 at 04:53 PM.
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Re: What do you use for an AC raw water manifold?
A $27 stainless steel manifold probably made by the chicoms. What can go wrong with that?
PVC is fine but should be schedule 80. Or you can use nylon or Marelon fittings. Whatever you do do not use brass.Pascal
Miami, FL
1970 53 MY #325 Cummins 6CTAs
2014 26' gaff rigged sloop
2007 Sandbarhopper 13
12' Westphal Cat boat
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07-12-2022 09:30 PM #6
Re: What do you use for an AC raw water manifold?
The one from hatteras appears to be bronze and at least in my boat has held up well, what's wrong with yours? Or just redoing the system?
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Re: What do you use for an AC raw water manifold?
His boat is Aluminum, it's a dissimilar metal issue.
Btw, I had a bronze manifold start to wear thru with pinholes.
All of our stuff is PVC now, some of it is at least 15 years old with no issues.CRICKET
1966 HAT50C101
Purchased 1985 12v71Ns
Repowered 1989 with 8v92TI
Repowered 2001 with 3406E
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07-12-2022 10:57 PM #8
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07-13-2022 06:08 AM #9Senior Member
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Re: What do you use for an AC raw water manifold?
Thanks for the input!
1 -- What's wrong with PVC?
Reports of catastrophic failures in marine applications, especially below the waterline, left a bad impression from early in my boating life. This application is high volume but above the waterline, so not as scary. Technical specs indicate that PVC strength drops off dramatically with temperature. Max pressure rating for PVC is at 73°F and it drops quickly from there. At 110°, it drops 50%. 140° is the maximum working temp, by which time the pressure rating is down to 22% of the full rating.
This will be in my ER, so 110° is expected.
It looks like Schedule 80 CPVC is far better, with a max operating temp of 220°F and only 50% strength loss @ 140°F.
2 -- I like the price of this Home Depot SS one
The price is very attractive. And 304 SS isn't a bad choice for materials. That it's made for propane/natural gas applications doesn't bother me, but the spec sheet from Home-Flex says it's max rated for 5psi. I don't know what pressure my AC raw water circuit will be, but that's extremely low...too low for me.
3 -- Or you can use nylon or Marelon fittings
I wish they did, but Forspar says they don't make the components I'd need to make a Marelon manifold.
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07-13-2022 09:51 AM #10Senior Member
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- Jul 2020
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Re: What do you use for an AC raw water manifold?
I don't have experience with plastic on a boat, but I don in my shop.
I have a couple machines that have filter systems that have shut off valves that look just like these.
they are on; I believe, 1.25" diameter pipe. They have never lasted. They work good when new, they a couple years later they lock up and won't turn. When that happens the red plastic handles just snap off. Now granted, these valves are in a dirty water system so it could be the junk in the water that makes them jam up. Just my experience. Don't know what other options there are but some kind of metal might last a lifetime instead of "It worked great until I needed to turn it off in a emergency" Just a thought.1980 53' Hatteras MY, Hull # 592
"Moon River" <-- Finally picked a name