Mailport February 2014 Issue

Mailport: February 2014

Joker Valve Search

I’ve been looking for a rubber duckbill valve for a vented loop in a holding tank system, and it seems Buck Algonquin ( has the right fitting. (My understanding is that the words “joker valve” and “duckbill” are interchangeable.)

Nigel Calder, in his book “Boatowner’s Mechanical and Electrical Manual,” makes an important point when he says “A vented loop in the discharge line will allow foul odors into the boat. It is best to attach a small hose to the vent and run it overboard.”

Forespar ( has a replacement duckbill cap assembly (MF-841) that does not vent overboard, and they offer a vent barb assembly (MF-846) that does not have a duckbill. It seems to me that you would want a duckbill in the loop so as to not clog the holding tank vent.

For an installation where you are pumping waste overboard, Buck Algonquin’s vent arrangement would seem to be the right choice. The joker valve part number is 60VL75CV; it is the one used in the Buck Algonquin 00VL75 assembly.

Ted Wasserman
Outbound 46
Marion, Mass.

Let us know how it works. An alternative would be to simply place a check valve in thew vent line itself. They are cheap, easier to clean, and easy to service inline; we often flush them with a hose or compressed air, and sometimes use acid for cleaning. And yes, a “duck bill” and a “joker valve” are the same thing.

Next: Mooring Design

Comments (1)

Can the author of the above article on the H2out filter provide me with a little more detail. It looks like he has a poppet check valve, exactly what one? Plus I noticed on the article in the January edition that their is a valve or another connection on the same line as the filter. I have tried to find more information on check valves but there are so many and this me in the letter above is a three way valve. Love to have the detail!
Neville Weir

Posted by: Neville W | April 9, 2015 9:46 PM    Report this comment

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