Blackwater discharge above the waterline?

[Dougtiff]

Well, there is nothing worse than getting up in the morning in the tropics and wanting to dive overboard in a anchorage with a number of boats anchored near by, and having you know what floating all around, so i put an Electroscan treatment unit in, and use it everywhere, even if not needed, no you know what floating around from me.

[Sailshabby]

Sterling Hayden didn’t have a problem with his toilet discharging above the waterline. Just sayin’...

[tarian]

Originally Posted by Sailshabby

Sterling Hayden didn’t have a problem with his toilet discharging above the waterline. Just sayin’...

Perhaps he liked the smell , each to their own , I suppose
there is a reason for a Ubend in domestic toilets as water sits in the U and stops the smell backtracking up into your house , now if you dont mind stinking out your cockpit, neighbours rafted beside you or you marina buddies go ahead and let them watch that lovely brown fluid slide down the outside of your boat and smelling
Or you can do what most designers and boat builders and a vast majority of sailors do and keep it under the water , but who knows we could all be wrong here.

[Cadence]

Originally Posted by GILow

Hi all,

A bit of a crappy subject but aside from aesthetic considerations, can anyone suggest a reason why you wouldn’t discharge blackwater from (fractionally) above the waterline?

It has occurred to me that this would remove one more potential point of failure from below the waterline.

Matt

You have my vote on discharging if you're doing it legally. Below the waterline if
you're not.

[FlyingScot]

Originally Posted by TrentePieds

Why is there a concern at all?

The probability of proper seacocks, properly installed, failing is exceedingly low. Seacocks should be "normally closed", i.e. only opened for the brief periods that they are functionally required to be open. If that is SOP in your boat, you obviously inspect the seacocks and their hose connections as you open and close them. If the inspection shows that a seacock is suspect, you repair it chop chop, don't you :-)?

TrentePieds

I'm not sure I would open and close a seacock every time I need to use the head. That's a little extreme in my opinion.

But no way I want the black tank to discharge above the water line. Smell, stains and I presume you would send some of the pathogens into the air.

I'm happy mine is near the bottom of each hull.

[Shrew]

Originally Posted by tarian

Perhaps he liked the smell , each to their own , I suppose
there is a reason for a Ubend in domestic toilets as water sits in the U and stops the smell backtracking up into your house , now if you dont mind stinking out your cockpit, neighbours rafted beside you or you marina buddies go ahead and let them watch that lovely brown fluid slide down the outside of your boat and smelling
Or you can do what most designers and boat builders and a vast majority of sailors do and keep it under the water , but who knows we could all be wrong here.

I owned a boat built in 1997 that had a discharge above water line from the factory. There is no odor or sludge. There is a discharge hose from the bottom of the holding tank to a macerator. The discharge from the macerator has an 'overtop' loop like most properly installed above water through hulls to prevent backflow of seawater.

When you use adequate holding tank chemicals, the only thing that gets discharged is green-blue 'water'. We would discharge beyond the 3 mile limit and do so while underway, not in an anchorage. (Ours was on the stbd side about 1 foot forward of the transom).

[Cadence]

On the lighter side. As a kid my friends and I would go to my parents moored boat to swim. One time we took this kid, with us, that swore he could swim. I put a life jacket on him.He asked what this hole was, as bobbing around, as Jerry pumped the head.

[boatpoker]

My discharge is 4" above the waterline. Never noticed a smell. Don't have any staining. Third boat I've done this with over the last 30 years ..... No problems.

[Nicholson58]

Ours passes over a vented anti-siphon loop. Discharge could be anywhere. We send nothing down the hole that we didn’t produce. Paper etc goes in a bag for later disposal. Macerator not required. Poo in the Caribbean disappears very quickly, paper lingers a while. We dispose of paper well offshore over deep water, preferably with Caribbean currents taking it west.

[Pelagic]

My holding tank is discharged with macerator pump....via a 2 way valve under the galley sink in a loop into the galley sink drain that has the thru hull outlet at the waterline.

Draining just below the boot stripe it does not stain the hull and I generally pump out at night after showers, when no one is swimming .

Our two toilets have their direct discharges, well below the waterline.

[GILow]

Thanks all, some great comments here.

I think I will go for the above-the-waterline option. As Pelagic suggests, just above the boot stripe, but high enough so that I don't have the problem Uncle G observed, that would annoy me too.

As for all the other stuff, please be assured this is a proper compliant setup with macerator etc, the places I will be sailing have some pretty clear regulations to be followed and I have no interest in spending my days worried about an inspection by the local water-authorities.

Matt

[GILow]

Originally Posted by FlyingScot

I'm not sure I would open and close a seacock every time I need to use the head. That's a little extreme in my opinion.

I agree it is a bit extreme, but I currently do this because the way my plumbing is setup the seacock handle is right next to the manual toilet pump handle so it is a simple additional action.

Having a boat with third-party-only insurance means you look for all practical ways you can to minimise risk to the boat.

[GILow]

Originally Posted by Dougtiff

Well, there is nothing worse than getting up in the morning in the tropics and wanting to dive overboard in a anchorage with a number of boats anchored near by, and having you know what floating all around, so i put an Electroscan treatment unit in, and use it everywhere, even if not needed, no you know what floating around from me.

This is a fair point, and it is the reason I have installed a holding tank. (Only solution available to me with my budget.)

I was watching friends on AIS and they would stay in the one spot for a a week then they "go for a sail" for a few hours and then come back. I asked them about this and they explained they were emptying their holding tank well away from other boats and that this was the accepted practice where they were sailing. It changed my whole understanding of the holding tank, which I had seen purely as a compliance issue up to that point.

Ironically, I had helped to plumb in their holding tank for them when they were preparing to go cruising, and I had not even remotely understood how it would be used.

[David B]

Originally Posted by GILow

Hi all,

A bit of a crappy subject but aside from aesthetic considerations, can anyone suggest a reason why you wouldn’t discharge blackwater from (fractionally) above the waterline?

It has occurred to me that this would remove one more potential point of failure from below the waterline.

Matt

Frankly I cannot think of any good reason to do this. Holding tank well above the waterline, gravity discharge straight out of the bottom via a short length of large-bore hose.
Holding tank is filled via macerator right at base of toilet, up to the top of the tank, so no potential for significant back-flow if the check-valve leaks.

Clean, out of sight below the waterline, no smell, and you can empty via the usual deck fitting to dock suction, when where discharge is not appropriate.

The single large through-hull with seacock is of course checked as part of regular maintenance, and has a bung tied to it as a safety back-up.

[Montanan]

I perceive the issue of the blackwater discharge being above or below the water line to be of less an issue than if the blackwater discharge is located adjacent to the below water freshwater intake supply line for your watermaker.