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Discussion Starter #1
My boat does not have a thru-hull for the black water output. I plan to drill a hole, and install the thru-hull and seacock. How far down relative to he waterline should the hole be drilled? Thanks in advance for the help.
 

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I would put the top of the hole just an inch or so under the waterline. The less pressure on a potential thru hull failure, the better, in my book. Unlike some others, it does not need to be submerged while heeled, so you don't need it down low.
 

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And put it aft of any, or planned, intake thru hulls.
 
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Ours is 6" above the water under the overhang aft, aft and above the rudder. It is placed so that nothing can run down the hull, (facing the water) but there is no resistance from the water, either.
 

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Discussion Starter #6
Ours is 6" above the water under the overhang aft, aft and above the rudder. It is placed so that nothing can run down the hull, (facing the water) but there is no resistance from the water, either.
The head on my boat is just behind the v-berth. It would be a long run to dump black water at the rear of the boat. Are long runs of tubing like this OK to do?
 

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keep the run as short as possible. being forward of the intake makes no difference. are you really going to use and an inlet while dumping the black water at sea. why do you need a black water outlet. dumping black water overboard is not really the thing to do in todays environment.
 

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Discussion Starter #8
why do you need a black water outlet. dumping black water overboard is not really the thing to do in todays environment.
We are planning to be offshore for extended periods on occasion. Need a way to release the black water on those occasions.
 

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... why do you need a black water outlet. dumping black water overboard is not really the thing to do in todays environment.
If you plan to go offshore you'll either need constipation pills or a huuuge holding tank, and high hopes to find a pumpout at the other end....
 

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Keep the tubing runs short, and buy the best tubing you can get. S m e l l . . .
 

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Another option would be a system to pump the tank while at sea via the deck pump out fitting what boat is it and what is the current head and tank installation here are a couple ideas that would in my opinion be better than a hole in the boat Amazon.com : Sea Flo 12v Macerator Water Waste Pump 45 LPM 12gpm Toilet Rv Trailer Camper Marine Boat : Sports & [email protected]@[email protected]@http://ecx.images-amazon.com/images/I/[email protected]@[email protected]@31NPs0xiLbL also adapt to deck waste pump out fitting
 

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Discussion Starter #13
The boat is a 1984 Bene First 35. Currently has a bag, but we will be converting to a rigid tank within the next year. The head is on the port side just behind the v-berth. The tanks is in the v-berth. The pump out is on the starboard side and about even with the back of the v-berth.
 

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keep the run as short as possible. being forward of the intake makes no difference. are you really going to use and an inlet while dumping the black water at sea.

Ummmm, yes. I am normally in countries without holding tank use, I often use the forward head and then have to carefully remember not to come aft to the galley and fill the sink for sea water washing up with the electric pump in araw water inlet half way along the boat. :eek:

But he other reason is that often the intake for the head is right next to the exit but forward of it. So you could pump out and in at the same time. Think about it.
 

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The head on my boat is just behind the v-berth. It would be a long run to dump black water at the rear of the boat. Are long runs of tubing like this OK to do?
No, I certainly wouldn't do a long run like that unnecessarily.
Sorry, that is for the aft head; I wasn't thinking of a forepeak head.
 
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Another option would be a system to pump the tank while at sea via the deck pump out fitting what boat is it and what is the current head and tank installation here are a couple ideas that would in my opinion be better than a hole in the boat Amazon.com : Sea Flo 12v Macerator Water Waste Pump 45 LPM 12gpm Toilet Rv Trailer Camper Marine Boat : Sports & Outdoors also adapt to deck waste pump out fitting
These are generally connected to the below waterline outlet. To exit the pumpout fitting (assuming these pumps can lift that far) would require a hose to go overboard to the water anyway. A connection that might not work perfectly on a rolling boat beyond the no discharge limits. Yuk.
 
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islander bahama 24
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These are generally connected to the below waterline outlet. To exit the pumpout fitting (assuming these pumps can lift that far) would require a hose to go overboard to the water anyway. A connection that might not work perfectly on a rolling boat beyond the no discharge limits. Yuk.
I should make a unit like I am thinking and patent it in my mind it will work great however most people have a hard time visualising my ideas think a hose screwing into the deck fitting then twist locking to the pump and a fixed 5 foot discharge hose with a weighted end to keep it pointed down and use it to pump the tanks when needed not every time you use the head
 

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I should make a unit like I am thinking and patent it in my mind it will work great however most people have a hard time visualising my ideas think a hose screwing into the deck fitting then twist locking to the pump and a fixed 5 foot discharge hose with a weighted end to keep it pointed down and use it to pump the tanks when needed not every time you use the head
Pretty sure I visualized exactly what you are thinking. I've seen plenty of dock side connections have difficulty, when the boat is not moving. I still think that's a risk. Then, what are you going to do with the contaminated hose, when you're finished? Yuk.
 
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From a safety standpoint having the backwater discharge above the waterline makes sense. I've seen commercial boats with such a set up. However, those were large enough that folks on deck weren't likely to get a whiff of any residual sewage once the pump-out was over and done. On a small sailboat that might not be the case.

I don't think you have to worry about having the backwater discharge forward of any intakes as long as they are on opposite sides of the boat. The discharge on our boat is just below the waterline on the starboard side, while the cooling water intake for the motor is about 8 or 9 feet aft of the discharge, but on the port side. Not much chance of the backwater slipping under the V of the hull, or the keel, and getting sucked up on the opposite side. Intake for the head is just forward of the backwater discharge, and inboard by a couple of feet, so as long as the boat is moving there isn't likely to be a problem there either.
 

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.... in my mind it will work great.... think a hose screwing into the deck fitting then twist locking to the pump and a fixed 5 foot discharge hose with a weighted end to keep it pointed down and use it to pump the tanks when needed not every time you use the head
A lot more complicated than an outlet plumbed to a seacock. Open valve, pump, close valve. No muss, no fuss - won't even have to wash your hands when done.:)
 
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