PVC connected to Thru Hull

[Chip Lohman]

I replaced the 6" high Marelon thru hull under the sink on my '86 32-III. This is the route taken by the cockpit drains. Using a 90 degree schedule 40 pvc connector, the drain hose now lays flat. The manufacturer of the PVC confirmed that the bursting pressure of any plastic fitting is only about 7,000 lbs versus the ABYC requirement for 10,500. I still have second thoughts. Even though the opening is about 12" below water level and less likely to freeze, the small amount of water in the elbow will be exposed to freezing air temps in the boat. Bubblers and heaters depend on a constant souce of AC. I'm tempted to undo this project. Any thoughts? I have thick skin so let fly with any admonishments...
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Whispering Swan, Quantico VA

 

[u079721]

I vote for undo

I have always understood that PVC fittings have no place on a boat below the waterline because the PVC is just not as strong as the glass reinforced Marelon. So the only way I would be comfortable with your fix is if you never leave the boat without closing that through-hull (which isn't a bad idea anyway).

But why use PVC in the first place? You can buy just about any shape fitting (straight, T, 45, 90) out of Marelon. That should allow you to keep your new improved routing of the drain hose without sacrificing safety.

 

[gareth harris]

Agree. Since at least one cockpit drain needs to be left open the whole time, you've got to be very careful with the fittings you use.
Gareth
Freyja E35 #241 1972

 

[Chip Lohman]

Thanks for the thought on replacing the 90 elbow with Marelon. I'm on a shopping mission... By the way, the elbow is before the petcock so will always represent "direct access" to the boat.

 

[Loren Beach]

"Elbow be Gone!"

Below is a picture of one of the Forespar valve bodies that can replace the plastic-elbow-to-a-valve setup that Ericson was so fond of.
My boat came with two of these worrysome elbows under the head sink. Now I have the new-style ones with the side barb-fitting exit and they are strong as heck and there is no standing water inside the plumbing before the valve to potentially freeze. Note that they can have different top sections that exit up or to any of four sides.

There is another messge on this site, dated about 11-02, showing a photo of my installation.

Best,
Loren in Portland, OR
Olson 34 #8

 

[ref_123]

PVC - "no-no"

At least, that's what the surveyor said, so I replaced the similar PVC elbow in the same place (on a similar boat, by the way, E32-3 1986) with Marelon... I think it was < $10, so it's not a big price for the peace of mind.

Regards,
Stanly

 

[clohman]

Thanks - the PVC is gone...

 

[Geoff Johnson]

I have a PVC elbow after the Marelon seacock and it is attached to that crappy wire coil reinforced bilge hose (OEM Ericson construction). It's on my list of things to replace. However, I never leave that seacock open, even when I am on the boat because it is below the waterline. The cockpit has two other drains above the waterline so it is really not needed unless you have green water coming into the cockpit.