Adding black water discharge, do I need Y-valve?

[Sandibar]

I'm changing the plumbing on my boat a bit in anticipation of sailing waters where pump-out stations are not available everywhere. Got a Jabsco diaphragm black-water pump to empty the holding tank offshore. Was thinking of splicing it to the same line that goes to the deck fitting for pump-outs with a T connector to below-waterline thru-hull. Do I need a valve in the line to separate the deck fitting from the Jabsco? I.e. does the Jabsco mind the suction from the pump-out station (thru-hull behind Jabsco would obviously be closed)?

Any insigths mucho appreciated!

[HopCar]

My gut feeling is that it should work. My set up is similar. There is a tee at the tank discharge. One leg goes up to the deck, the other goes to a macerater pump for discharge overboard. Works fine for me but my pump doesn't have the valves that a diaphragm pump has.

[fallingeggs]

I've been thinking through the same issue and I didn't even consider whether the y-valve was necessary.

Although, I was more focused on the USCG requirement that one has to have away to prevent discharge of waste overboard when in coastal waters. If no y-valve to lock (as I currently do in the plumbing of the head -> y-valve -> overboard), can you meet this requirement? Maybe locking the pump handle works? Maybe you won't sail in US costal waters?


Edit: I see you're in Finland, so I guess this worry won't apply to you! Still interested in your answer.

[Tayana42]

Mine is also set up this way, a t after the tank one leg leading to deck fitting and the other to a Whale Titan manual pump to a below the waterline through hull. I've used it this way for 7 years. I always, always, always keep the seacock closed except while pumping. No problem with deck pump out.


S/V B'Shert

[Sandibar]

Fallingeggs, no plans to sail US waters, but in any event the thru-hull (seacock?) will be closed always, except when pumping out offshore. Not sure if this would be ok in the US, but here it's not a problem.

The current set up actually has an Y-valve at the bowl pump and I can choose to pump directly overboard or into the tank. Since pumping overboard requires the thru-hull to remain open, which I don't like, I'm changing to a simple pump (without y-valve) at the bowl and will always pump first to holding tank. Then either use a pump-out station or open the thru hull for the two minutes it takes to empty the tank overboard.

[Sandibar]

Tayana42 and Hopcar, thanks for the info. I was thinking of going with a manual pump, but don't have a good space to work the lever. I think I'll skip the valve for now and just install the pump.

[HopCar]

The closed and locked seacock satisfies US requirements. No Y valve required. Peggie Hall taught me a nice trick concerning that. Since the only way for sewage to get overboard on my boat is through an electric pump, Peggie suggested I use a keyed switch to activate the pump. This would allow me to leave the seacock open and still be legal.

[fallingeggs]

Originally Posted by HopCar

The closed and locked seacock satisfies US requirements. No Y valve required. Peggie Hall taught me a nice trick concerning that. Since the only way for sewage to get overboard on my boat is through an electric pump, Peggie suggested I use a keyed switch to activate the pump. This would allow me to leave the seacock open and still be legal.

Very good to know! I don't have an electric pump, so I need to figure out how to lock a Spartan seacock closed.

Removing the need for y-valve would be nice, so I'm still interested to hear if someone can confirm the OP's question.


Sent from my iPhone using Cruisers Sailing Forum

[Stu Jackson]

No reason for it not to work.

Think about how it is arranged: As long as the deck cap is on and tight, all that hose is is an empty pipe, so the pump could care less. Once you use the deck fill for pump out with the seacock closed, the pumpout pump sees no difference.

Draw a sketch if you must, but this is kinda basic.

gl

[HopCar]

Fallingeggs, you could secure the manual pump instead of the seacock. which ever is easier. You don't need a lock. A tie wrap that has to be cut should make the Coasties happy. They are not trying to prevent you from pumping overboard. They just want it to be a deliberate act, not by accident.

[jamhass]

An alternative

I used an inexpensive manual whale gusher diaphragm pump with appropriate hose and fittings to pump out from the deck fitting itself. Somewhat less convenient than an installed solution, but cheap, effective and trivial to set up. Has worked well for 6 years.

[Sandibar]

Originally Posted by Stu Jackson

No reason for it not to work.

Think about how it is arranged: As long as the deck cap is on and tight, all that hose is is an empty pipe, so the pump could care less. Once you use the deck fill for pump out with the seacock closed, the pumpout pump sees no difference.

Draw a sketch if you must, but this is kinda basic.

gl

Yes, no problems anticipated when pumping out at sea. I was concerned that the boat's diaphragm pump won't like the pressure difference when using an external pump-out station through the deck fitting. I.e. there is suction from deck side of the pump and a closed thru-hull on the other side. Pressure either equalizes through the pump, or it seals the thru-hull side of the pipe and the pressure difference remains as long as the station pump is operated. I don't know how these diaphragm pumps operate and if the pressure difference will damage the pump. Don't think it will, but just wanted to make sure. With the above feedback I'm pretty confident it will be ok - thanks everyone!

[guyrj33]

No Y valve required, a T fitting will work just fine. The diaphragm pump will allow contents of the holding tank to be sucked thru the pump valves.

[Sandibar]

Thanks. To make all your weekend a little sweeter: changed the bowl pump and installed the electric diaphragm pump today and got sh***y glycol in the toilet and all over my hands. Gas mask helped.

[Cadence]

Originally Posted by HopCar

Fallingeggs, you could secure the manual pump instead of the seacock. which ever is easier. You don't need a lock. A tie wrap that has to be cut should make the Coasties happy. They are not trying to prevent you from pumping overboard. They just want it to be a deliberate act, not by accident.

That tie wrap thing, I always found humorous. A bundle of tie wraps and a pair of dikes in a draw next to the valve. It may stop an accidental discharge but that is it