Will it sink? Really dumb question

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rhino_mac

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Ok, sorry for the really dumb question. Just made my first foray into the engine compartment.

So I need to empty my holding tank. It is literally filled with poo and worse still its not my poo having never used the toilet.

The boat is a Monterey 250 and its fitted with a macerator and holding tank. The sea cock from the macerator to the bottom of the hull ( which I have now found having plucked up the courage to open the engine hatch). I've turned it on (it was off) so I guess turning on the macerator offshore some way will empty the holding tank.

My question is, can I leave it on and go out on the boat and empty out to sea (boat is on dry berth at the moment). Or should I turn it back off and turn it on/back off once I'm at sea?

Basically, will the boat sink if its on for any period of time?

Told you it was a dumb question!
 
Surely it's taken you longer to type the question that it would have done to shut the valve again! :D

It wont flood the boat, but on some boats the holding tank will backfill if you leave the sea cock open whilst cruising. On other boats it doesn't, but it's good practice to close the sea cock anyway and just open it to empty the tank. The macerator is usually part of the toilet by the way, the bit between the tank and the outlet is just a pump.
 
Nick_H said:
Surely it's taken you longer to type the question that it would have done to shut the valve again! :D

It wont flood the boat, but on some boats the holding tank will backfill if you leave the sea cock open whilst cruising. On other boats it doesn't, but it's good practice to close the sea cock anyway and just open it to empty the tank. The macerator is usually part of the toilet by the way, the bit between the tank and the outlet is just a pump.
Click to expand...

Hi Nick, I think it might vary by installation - on my boat there's a primary macerator and pump in the base of the toilet, like yours I think - but there's another macerator pump used as as the discharge pump from the holding tank (ie complete with blade etc).

Cheers
Jimmy
 
Rhino, our last boat was a 250. Just open the s/cock when you're sufficiently 'offshore' then you'll need to hold the panel switch down anyway to empty the tank. It'll change tone when it's done so you'll know when to release the switch. Then just close the seacock after. We never left ours open.
L
:)
 
lisilou said:
We never left ours open.
Click to expand...
Ok, but what if you would? This is the OP question, as I understand it.
Generally speaking, I would think that it should be designed to avoid the "backfilling" which Nick mentioned, though I can't be positive for that specific boat.
In which case, it shouldn't hurt to leave it open.
Mind, I agree that it's good practice to close every tub hole when not used, but I for one wouldn't even consider going through my 7 seacocks and open/close all of them before/after going at sea... :)
 
Alternatively, use a pimp out facility. I believe there is one at Poole Quay - downstream of Poole Town Lifting Bridge - so no Bridge aggro.!
 
MapisM said:
Ok, but what if you would? This is the OP question, as I understand it.
Generally speaking, I would think that it should be designed to avoid the "backfilling" which Nick mentioned, though I can't be positive for that specific boat.
In which case, it shouldn't hurt to leave it open.
Mind, I agree that it's good practice to close every tub hole when not used, but I for one wouldn't even consider going through my 7 seacocks and open/close all of them before/after going at sea... :)
Click to expand...

Yeh, sorry..after I typed it I thought...'hmmm didn't actually answer the question tho.' We didn't feel comfortable leaving it open is the best answer I can give.
L
:)
 
Thanks for the help guys. I think I'll take Lisalou's advise and just open it when I'm at sea and close it off.

Just out of interest, my toilet seems to be the very basic manual pump type that pumps into the holding tank. There is then a pipe that leads to a seperate macerator that goes via a seacock to the bottom of the boat.

The reason I wondered if I could keep it open is because you have to move the front seat forward, remove the rear seat then open the engine hatch and bend down into the depths of the bilge to turn the sea cock. It's a right pain so I figured of I could leave it on safely I would.
 
rhino_mac said:
Thanks for the help guys. I think I'll take Lisalou's advise and just open it when I'm at sea and close it off.

Just out of interest, my toilet seems to be the very basic manual pump type that pumps into the holding tank. There is then a pipe that leads to a seperate macerator that goes via a seacock to the bottom of the boat.

The reason I wondered if I could keep it open is because you have to move the front seat forward, remove the rear seat then open the engine hatch and bend down into the depths of the bilge to turn the sea cock. It's a right pain so I figured of I could leave it on safely I would.
Click to expand...

What's the position of the holding tank in relation to the waterline?

Cheers
Jimmy
 
Now I understand why the exit of the holding tank on some boats is above the waterline... silly me
 
rhino_mac said:
It's above the waterline. Top of the tank is close to the deck just under the engine hatch
Click to expand...

In that case, although leaving the seacock open is arguably bad practice, the tank won't fill up if you do so. The contents might generally leak out a bit past the macerator pump, but that's a different question.

Like others, I keep the seacock closed, opening it only when pumping out - but in my case the top of the tank is only fractionally above the waterline, so the tank does fill up with seawater if the seacock is left open.

Cheers
Jimmy
 
For what it's worth, we leave all the seacocks on our boat open all the time (except that I work them open and closed a few times when I remember, to stop them sticking). All the plumbing is new and properly done, with vented loops where appropriate, and I am not worried that the hoses are going to suddenly jump off the tails for no reason. This is on a sailing boat, but I can't see that it makes any difference.

Pete
 
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