Do I need a macerator?

[Chris & Lenore]

Plumbing in the offshore holding tank emptying system.
The bottom of the holding tank is a foot above the thruhull and has it's pumpout fitting at the bottom (no dip tube).
Will gravity be sufficient or do I need a macerator pump?

Thank you ,
Chris

 

[dlochner]

Is the bottom of the tank above the waterline at all angles of heel? If not it will only drain to the waterline or when heeled water will enter the tank.

 

[Chris & Lenore]

Oops. I'm guilty of not searching before posting lol .
Found the recent post explaining "gravity dumping".
Looks like I just need to confirm my holding tank is above the waterline and not just above the thruhull .

Chris

 

[Chris & Lenore]

But I do have one question. I need to also keep the deck pumpout .
Do I really need a Y valve in the tank discharge or simply T it to both the thruhull valve and deck fitting? Seems to me I'd just have to open the thruhull valve to enable dumping and when closed the deck fitting is enabled?

Chris

 

[dlochner]

The Y valve typically goes between the head and the holding tank. In one position it directs the discharge directly to the sea in the other position it will be directed to the holding tank.

The definitive work on all things smelly is Peggy Hall's Book
The New Get Rid of Boat Odors: A Boat Owner’s Guide to Marine Sanitation Systems and Other Sources of Aggravation and Odor A lot of your questions will be answered in the book.

 

[Chris & Lenore]

Lol. Must be too early. I found the answer further down in the thread I mentioned earlier.
I do have Peggy's book but it's on the boat and I'm not. Great book.

 

[Peggie Hall HeadMistress]

Do I really need a Y valve in the tank discharge or simply T it to both the thruhull valve and deck fitting?

Since you're setting the system up to dump via gravity, a tee or a wye will be ok. If there's to be a overboard discharge pump, you'd want a y-valve so you could cut off the flow of waste to the pump when it needs work. 'Cuz nobody ever discovers that the pump won't work when a tank is empty!
--Peggie