Hi Tor,
Emotion and other opinions aside, let's look at the system requirements.
1. You need to distribute salt water (corrosive) to several points at a pressure of 1.5 pounds static.
2. Falling off a 50 foot wave will induce a pressure spike of 25 pounds or so, giving a dynamic and static pressure total of 27-30 psi.
3. PVC (Schedule 40) will withstand 120 psi 140 degrees.
4. You will die at sustained temperatures of 140 degrees.
5. PVC doesn't corrode.
6. You and anyone on your boat will not be walking, stepping, jumping, chewing, drilling, sawing, jackhammering or any other destructive processing on the PVC.
7. Occasionally, you'll be having a look at the PVC. Maybe even operating the valves.
8. You will live less than 100,000 years (the estimated life of PVC in seawater). The boat will survive less than 100,000 years. You will sell the boat before 100,000 years pass. You get the idea.
9. PVC is easy to construct and install
10. PVC is cheap and is not subject to galvanic or other metallic corrosions.
11. PVC is a well understood and tested material.
That's about it. Admittedly, my investment into my home is less than yours, but I trust what works for a bazillion homes and industries to work in the relatively benign environment I've put it to work. I've used PVC in nuclear applications. Not irradiated but in water treatment.
What it boils down to is new materials in new uses – tradition, which is all important in marine applications – is subject to new tests and new applications. I really believe it's ready for prime time in underwater applications. When ships were of wood and men of iron then valves of bronze were de rigeur. New times, new materials, new processes.
When all is said and done, an engineered material is useful within it's design parameters. PVC falls well within those parameters.
And now, I've said all I'm going to. You can spend 100 or 200 dollars on bronze. You can bond you boat everything to everything. Or for around 60 dollars you can have a manifold that will last of 100,000 years. Maybe more.
But, that said, I'm not a licensed engineer. So your results may vary. As I said before, in 30 years we can compare manifolds. I'll bring the wine and beer. And Yukon Jack, the official drink of Pelican. 🙂
Bob
2008/9/16 Silver Heels < ([email][/email])>
Tor
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Silver Heels, P-424 #17
http://www.SilverHeels.us
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