PSS vent line

[jsalley]

I'm thinking about adding air conditioning to my 2006 Catalina 309, and trying to avoid adding an additional below-waterline thru-hull. The boat came with a vent line on the PSS shaft seal that goes to a seacock/thru-hull with a bronze scoop strainer. Reading the installation literature from PYI on the PSS shaft seals, it looks as if there is no need to have the shaft seal vent line connected to a water source on a sailboat that cruises under 12 knots, and the vent can simply be led above the waterline and open to the air. If that's the case, I should be able to remove the present water-cooled vent line and reroute it to a point well above the heeled waterline, freeing up the thru-hull/seacock for the AC pump.

Anyone else have their PSS vent plumbed this way, and is there any reason I shouldn't change it from Catalina's original installation?

 

[sailaway78]

Vent Line

I have a PSS and the vent line for it is just run well above the water line, and is open to atmosphere. No thru hull, no sea cock, just a vent hose. I can see no need for it to be run through a sea cock or thru hull. Just make sure that the open end can't get below the water line under any circumstances.

 

[FastOlson]

Be aware that the model of the PSS without the vent fitting was standard for many years for boats that motor under 12 kts.
The reduction in product choice to one model with a vent pleased their liability lawyer(s) and simplified both production and marketing for PYI. And slightly raised the build cost (and retail price) of your boat -- truly a "win win" situation for everyone except the customer.

Just vent it to the air, well above any possible level that water might rise to...
(Or just put a plug in the top of the shortened hose and remember to burp the face fitting on the bellows after you launch from the travelift ... )

 

[Maine Sail]

If that scoop strainer faces forward you do not want to connect your AC there or it will back fill when moving forward.

A PSS can be air vented but keep in mind that reverse thrust can force salt water out the top of the vent line.

On my 310 I fed it to a bicycle water bottle to catch reverse thrust water.

On our current boat I use a Taco hydronic heating system vent. It is the brass colored device next to the siphon break.

 

[Maine Sail]

Be aware that the model of the PSS without the vent fitting was standard for many years for boats that motor under 12 kts.
The reduction in product choice to one model with a vent pleased their liability lawyer(s) and simplified both production and marketing for PYI. And slightly raised the build cost (and retail price) of your boat -- truly a "win win" situation for everyone except the customer.

Just vent it to the air, well above any possible level that water might rise to...
(Or just put a plug in the top of the shortened hose and remember to burp the face fitting on the bellows after you launch from the travelift ... )

Despite what PSS insinuates the real story, from my reputable inside source, is that air CAN accumulate up in the shaft logs of MANY boats. This trapped air can come from reverse thrust and cavitation bubbles or sailing in rough conditions. Burping just once per year worked on SOME boats but not all. One of our boats needed burping about every three weeks so the vented PSS was 100% necessary to prevent cooking the seal.

If you have one with a vent it is best to utilize it. Please never ever put a metallic plug in the carbon bearing or you will have issues. A small ball valve on the hose end is fine and can be opened periodically to manually burp it but not soak your engine room with salt water.

Their original no-vent theory on sail boats was solid except for one big point, they forgot about trapped air..

 

[seadaddler]

Vent

What Main sail said is true and I had water come out of the vent once on a hard reverse trust so don't plug either run it high above water line or like Main sail did which I keep saying I will do some day but never had water come again so it's been ok and I never have had to burp it either.
Nick

 

[jsalley]

If that scoop strainer faces forward you do not want to connect your AC there or it will back fill when moving forward.

Not sure why this is a problem. Wouldn't forward movement of the boat just force water in a forward direction through the AC lines?

 

[Maine Sail]

Not sure why this is a problem. Wouldn't forward movement of the boat just force water in a forward direction through the AC lines?

Is this line for AC cooling or condensate draining? Many of the AC units these days are air cooled. I suspected it was for condensate draining which you would not want the scoop facing forward for. If it's for cooling it should be fine.

 

[jsalley]

It's for cooling. Looking at either the Mermaid or Webasto reverse cycle units - was referring to the pumped seawater line.

 

[Ross]

Despite what PSS insinuates the real story, from my reputable inside source, is that air CAN accumulate up in the shaft logs of MANY boats. This trapped air can come from reverse thrust and cavitation bubbles or sailing in rough conditions. Burping just once per year worked on SOME boats but not all. One of our boats needed burping about every three weeks so the vented PSS was 100% necessary to prevent cooking the seal.

If you have one with a vent it is best to utilize it. Please never ever put a metallic plug in the carbon bearing or you will have issues. A small ball valve on the hose end is fine and can be opened periodically to manually burp it but not soak your engine room with salt water.

Their original no-vent theory on sail boats was solid except for one big point, they forgot about trapped air..

My boat has a stern tube with the cutlass bearing installed there. When I burp the PSS seal it takes a few seconds for the water to fill the tube. I think that boats with a strut could have a concern with the back wash from the prop because their stern tube is unrestricted.

 

[ronbo]

If your question is: Can I use the PSS vent thru-hull to feed my AC, the answer is yes, but make sure it's large enough for your AC.

Ronbo