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Fresh water tank discharge vent

Posted: April 24th, 2019, 9:27 pm
by samcrouse
I have a '99 Carver 504 CPMY and a question about the fresh water filling and knowing when the tanks are full.

Here is an excerpt from the manual on Page 66.

Put only clean, fresh water into your water tank. Your tank is full when water is discharged from the stainless steel water tank vent fitting installed on the side of the boat's hull. Refer to the Above the Waterline Thru-Hull Fittings portion of Section 9 for the exact location of the water tank vent fitting. DO NOT overfill your water tank OR leave a fill hose unattended while the tanks are being filled.

I have filled the tanks and while the gauge indicates full, I have never been able to see or located a water tank vent fitting to see any discharge from it indicating the tank is full. I went to section 9 and cannot located a water tank discharge vent. The only one I see is #14 and that seems to be a water air vent as it is way up near the gunwale, which seems to be too high for a water discharge overflow.

Can anyone tell me where their water tank overboard discharge vent fitting is?

Thanks, Sam

Re: Fresh water tank discharge vent

Posted: April 25th, 2019, 4:58 am
by Midnightsun
Do you normally just watch the gauge and wait until it is full or do you fill until it overflows at the filler cap? Either way works fine however you do need to get it really full if you want water to exit the vent which implies not only the tank being completely full but also the fill line to a point higher than the vent location.

Not really sure why they say "DO NOT overfill your water tank OR leave a fill hose unattended while the tanks are being filled" as I cannot count the number of times I have seen hoses running full bore while the water is overflowing from the filler port and vent with nobody watching. :blush: The difference between overflow from the filler as opposed to only the vent is a few pints in some cases which would be hard to control. Personally I normally go by sound just like when I fill fuel. ;-)

I no longer need to worry about filling with a hose as it is now semi automated via a float switch that shuts off the water supply from shore water. No more hoses or vent watching :-D See here. viewtopic.php?f=13&t=3143&hilit=lazy+mans

Re: Fresh water tank discharge vent

Posted: April 25th, 2019, 5:31 am
by mjk1040
Pretty sure the vent your looking at is the Fresh Water Tank vent. Our 355 water tank will over flow at the fill port most generally before water will come out the vent, but it does come out. The vent may be plugged by a spider nest or other insect. Sometimes you can take the vent cover off and inspect for blockage. Unless you have a loose fresh water tank fill hose I don't believe you can do any damage overfilling this tank.

Re: Fresh water tank discharge vent

Posted: April 30th, 2019, 4:03 pm
by samcrouse
Thanks MJK and Hans. I was able to resolve this with your answers, answers from Carver (rep there in Pulaski, named Bryan Volez, and a tip from my broker. We found all four tanks, which does make it a 350 gallon total. Also, suggested was to purchase a flow meter for the hose to give us an indication of how much water is actually being put into the boat from the hose.