Waste Overboard Port

[O C Diver]

If your boat has a holding tank overboard pump, does the waste discharge above or below the water line? My boating experience is mostly with charter and commercial boats. Can't remember one with a below water discharge. I prefer to have fewer hull protrusions below the water line and am thinking about moving mine above the water but under the swim platform. It will still have a seacock and it's unlikely that I will ever use the overboard system, but then options are always good.

Ted

 

[psneeld]

On most pleasure boats I have been on and/or serviced...they are below the waterline.

I too wish mine was above the water for flooding/security issues....I'm curious as to anyone with a Raritan LectraScan that has a discharge above the waterline and whether there is odor with the discharge.

If not...I may consider changing mine.

 

[markpierce]

My blackwater discharge is inches below the waterline. Its valve is always closed. Shower water and manual sump pump discharges are adjacent and those valves are usually kept closed too. Sink and electric/automatic bilge pump discharges are inches above the waterline and are usually/always kept open.

Under-waterline discharges:

 

[Bay Pelican]

I have never seen a boat with its waste discharge from a holding tank above the waterline. When the water is clear enough I have watched our pump outs and would not want that discharge to be on the surface and likely floating.

Conventional wisdom was to loop the discharge line upwards inside the boat so that the discharge line reached a point above the water line and thus would not flood the holding tank if the thru hull was left open.

In the last few years I have seen more and more boats do away with the above the water line loop and just have a direct discharge. This requires the thru hull be closed unless pumping out. I am happy with this arrangement as it reduces the length of the discharge hose (potential smell) and allows me to rinse the discharge hose with sea water after the pump out and before I close the thru hull.

 

[CaptMatt]

Ted - I'd go with under the water and put on a thru hull that you can close. I've seen a few guys put these above water and it is NASTY! You wouldn't use that when divers are in the water would you? lol

On the electra-san/scan question. I have mine going below water, but, during winterization I've had to pump out what's left in the system. It is not overly unpleasant, smells like chlorine and looks more like water. Note, if the electrasan isn't working correctly it will still pump and well.. then anything goes.

 

[FF]

IN the painted water line is least nasty , unless the water ices and you use non white TP

For the least hassle with the coasties ,,A simple U discharge pipe or hose that could be pushed into the waste deck fitting (many can now lock in place and aimed down would solve the problem.

Overboard Waste discharge? , no sir , one is not fitted .

 

[fryedaze]

I never use mine due to the type of cruising we do.

 

[caltexflanc]

Black water definitely below the waterline for all reasons mentioned, with a vented loop and seacock. Macerator pump, switch, through hull/seacock, Y-valve, vent, tank inlets and outlet all grouped together for convenience in our utility/generator room. When I used it was of course out in open water past the three mile line, typically at idle speed. Nice to have the stuff being discharged 3 feet under...

 

[Moonstruck]

I have never seen a boat with its waste discharge from a holding tank above the waterline. When the water is clear enough I have watched our pump outs and would not want that discharge to be on the surface and likely floating.

Conventional wisdom was to loop the discharge line upwards inside the boat so that the discharge line reached a point above the water line and thus would not flood the holding tank if the thru hull was left open.

In the last few years I have seen more and more boats do away with the above the water line loop and just have a direct discharge. This requires the thru hull be closed unless pumping out. I am happy with this arrangement as it reduces the length of the discharge hose (potential smell) and allows me to rinse the discharge hose with sea water after the pump out and before I close the thru hull.

Marty, I think you probably omitted "vented loop". This is an important distinction because the vent breaks the siphoning action that can still flood the boat.

For those not familiar, here is a kind of primer on vented loops.

Vented loops and anti-siphon valves ; how they work on boats

 

[rwidman]

If your boat has a holding tank overboard pump, does the waste discharge above or below the water line? My boating experience is mostly with charter and commercial boats. Can't remember one with a below water discharge. I prefer to have fewer hull protrusions below the water line and am thinking about moving mine above the water but under the swim platform. It will still have a seacock and it's unlikely that I will ever use the overboard system, but then options are always good.

Ted

To answer your question, mine is above the waterline.

To offer some unsolicited advice, I don't think you will gain anything from moving yours. Filling the hole is much more involved than just plugging it, you have to grind out some fiberglass and taper the patch. Leaving the thruhull and capping it off is the easiest way to abandon it so why not just leave everything as it is and save yourself the trouble and expense?

 

[Phil Fill]

I removed and filled in all the underwater through hulls except for the two for the engines, 7 of them. This was recommended by our insurance company. Every thing is now pump up/over and I sleep better at night.

 

[ksanders]

We have a Raritan Purasan.

The discharge is through a 1.5" seacock below the water line.

It also has a vented loop to prevent siphoning, and we close the seacock when we are not on board. No we do not close it if we are just going ashore, only if we're leaving the boat for overnight.

Cant speak for the smell but can attest that you can see the discharge momentarily from the purasan. One of the criteria is that there are no visible floating solids. It puts out cloudy colored water with no visible particles.

 

[HopCar]

Mine is below the waterline. I don't like the idea of an above waterline discharge for sewage. That said, I don't think I'd go to the trouble to change it if it was above.

I might head the boat to windward at a fast clip when ever I emptied the tank.

 

[jleonard]

My holding tank discharge is above the waterline. Factory setup.

 

[rwidman]

Mine is below the waterline. I don't like the idea of an above waterline discharge for sewage.

Most of us buy our boats and take whatever comes with them. I can't see someone passing on a boat they otherwise love because the overboard discharge is above the waterline.

Putting the discharge above the waterline saves several hundred dollars in material and labor and accomplishes the same thing, removing poop from the boat to make room for more poop.

 

[caltexflanc]

I'm curious Ron, how does it save hundreds of dollars? I can only think of a seacock as the extra cost of below waterline. What am I missing?

 

[HopCar]

Ron, you didn't finish quoting my statement. I think we agree on this one.
It's not a big deal either way. I just prefer it below the waterline.

 

[HopCar]

George, in most cases you'd need a seacock or valve on the sewage discharge anyway. Some silly law about locking the valve.

Yes there are ways around needing a valve to comply, but it's just not a big deal.

 

[Billylll]

I use where legal a PuraSan hold and treat system with my own holding tank. It originally discharged under the water line through a vented loop and a through hull with a locking handle. Last year I changed the transfer pump from a Jabsco to a SeaLand diaphram type pump. I also used the below the waterline through hull for a raw water anchor wash down pump and changed the treatment systems discharge to an above the waterline discharge. I still have the vented loop and I have more stains from my AC units than the PuraSan. Either way will work. Just make sure you have a method for locking the discharge to comply with NDZ USCG regulations. In my case not only does it require turning on the treatment systems DC breaker I need to change the divertor valve from the deck pump out fitting to the SeaLand pump in addition the H-N-T requires a key and the discharge has a handle I can lock closed and remove.
Either way worked fine for me where it's legal to discharge treated waste. I'm doing the identical setup on my Gulfstar. I prefer fewer below the water line through hulls or sea cocks.
Bill

 

[rwidman]

I'm curious Ron, how does it save hundreds of dollars? I can only think of a seacock as the extra cost of below waterline. What am I missing?

Bronze thru-hull instead of plastic or nylon, seacock, extra sanitation hose for the loop and the anti-siphon device (the exact name escapes me at the moment). And the labor and space for the extra components and loop.

My macerator outlet connects with about a foot of sanitation hose to a $20 thru-hull. A couple of clamps and that's it. There's no possible failure that would endanger the boat.

 

[rwidman]

George, in most cases you'd need a seacock or valve on the sewage discharge anyway. Some silly law about locking the valve. .

I installed a key switch in the macerator circuit. No key, no pumpout.

 

[Billylll]

Bronze thru-hull instead of plastic or nylon, seacock, extra sanitation hose for the loop and the anti-siphon device (the exact name escapes me at the moment). And the labor and space for the extra components and loop.

My macerator outlet connects with about a foot of sanitation hose to a $20 thru-hull. A couple of clamps and that's it. There's no possible failure that would endanger the boat.

That will work Ron.
Bill

 

[O C Diver]

Ok, maybe I should have offered a little more Information. I'm in the yard now doing the engine swap and exterior paint job. My single engine boat has 5 seacocks . Most were put in really bad spots, easy to trip over or centered in an ideal storage area. The goal is to reduce the number and relocate ones that waste a great deal of space. 4 of the 5 will either be eliminated or relocated. While doing it properly takes time, filling 4 holes isn't 4 times the time of 1. My lazeret has the waste seacock in the middle of the starboard side. I'm not going to stack a spare anchor, fenders, ect. on top of it; not willing to give up the space. May compromise and go through the transom, just above the hull, behind the rudder. Would really rather have it above the water line. Mine has the loop above the water line with the siphon break.

Ted

 

[Bay Pelican]

Marty, I think you probably omitted "vented loop". This is an important distinction because the vent breaks the siphoning action that can still flood the boat.

For those not familiar, here is a kind of primer on vented loops.

Vented loops and anti-siphon valves ; how they work on boats

You are right about the vented loop. Bay Pelican came without a vent on the blackwater discharge and unless I could vent it outside the boat I doubt I would have put one in.

 

[Vashon_Trawler]

Below the waterline for my boat--builder installed and works well.

 

[FF]

The best vented loop has a line from the vent up as high as can easily be done.

The vents with just a check valve are subject to waste pushing the valve closed , which requires the valve to be frequently cleaned , to be of any safety value.

 

[psneeld]

The best vented loop has a line from the vent up as high as can easily be done.

The vents with just a check valve are subject to waste pushing the valve closed , which requires the valve to be frequently cleaned , to be of any safety value.

...just yesterday I caught my OEM vented loop back siphoning....my dry bilge wasn't so dry...

 

[Searios]

CA design guidance for BW tanks and pump-out

Here is an easy reading document about piping, tanks and thru-hulls for holding tanks located below the waterline.

http://www.dem.ri.gov/programs/benviron/water/shellfsh/pump/pdfs/podesign.pdf

If the bottom of your holding tank is above the waterline then a siphon break should not be required since the vent line from the holding tank will do the "siphoning"

 

[magicbus]

My single engine boat has 5 seacocks
Ted

Hmmm... main.. genset...a/c...freezer...black tank... plumbed watermaker not installed.. salt water washdown.... plus a get-home. 5 doesn't seem so overboard!

Dave

 

[sailormike]

our macerator pumps through a through hull mounted 1-2 inches above the waterline. We use plenty of wales chemical which dyes the waste a deep dark blue and keeps odors down.