Vented loop

[Badger, C-27, N.H.]

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I recently bought a 1974 Catalina 27 with an A-4 that appears to be well taken care of.

On the starboard wall of my engine compartment is mounted a curved plastic tube with an exit at the top.

The previous owner says it was intended to be what she called a "vented loop" which she never finished installing. Now she can't remember how it was supposed to work.

It has no tubes running to it at the moment.

Can anyone tell me what it does and what else it needs for parts? Do I really need it?

Badger

Great Bay, New Hampshire

[Don Moyer]

Badger,

You're describing an anti-siphon valve which is necessary on exhaust systems where the engine cooling water is routed well above the water line and then down to a water entry fitting on the hot well below the water line.

The original Catalina 27 exhaust configuration had the engine cooling water entering on the downhill side of the hot section of the exhaust, well above the water line, and the exhaust hose ran downhill from there to the back of the boat. In other words, it doesn't really need an anti-siphon valve which is probably why it was never connected.

I'm attaching a sketch of the Catalina 27 exhaust system provided by Catalina so you can check to be sure this is still the system installed on your boat.

Don

[Badger, C-27, N.H.]

Thanks very much Don, for the info and this website. (nm)

nm........