Vented Loop on a Cat

[svneko]

Hi Peggie, I have a sailing catamaran, where the head is never below the waterline. Currently, the head is plumbed directly to a SS holding tank. The tank has a valved, gravity-fed overboard discharge to a through hull and a separate tank discharge to a pump out fitting on deck. Where legal, I would prefer not to pump the "stuff" into the tank and then overboard. I am considering adding a Y valve between the head and the tank connected to a Y junction in the line from the tank to the overboard seacock. This way the head can discharge directly overboard. Do I need the vented loop since the head, tank and all hoses (except leading to the through hull) are always above the waterline? Fitting a vented loop in will be difficult.

Bonus Question: Does the Dometic vent filter do anything?

Thx much

 

[Peggie Hall HeadMistress]

Nope...no vented loop needed this time.

But you do need to know that your SS tank is living on borrowed time. 'Cuz urine is so corrosive that TYPICALLY any metal tank, even 316 SS will start to leak at a weld--seam or fitting within 2-5 years and turn into a colander within 2-5 years. Those are average time spans, but they don't vary much.

Answer to bonus question: vent filters do trap odors from the tank, but they also help to create 'em. It's easier and a LOT cheaper to improve conditions in the tank to prevent odors instead.