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Old 13-03-2021, 11:00   #31
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Re: Why does cooling water exit above waterline?

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Originally Posted by meirriba View Post
Probably you are mistaken.
I have never seen kitchen sink on a boat to be drained underwater.
You would need a pump to press the discharged fluid into the sea.
Rubbish. As soon as the fluid rose above the waterline, it would start to flow into the sea. No need to push water downhill.
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Old 13-03-2021, 11:04   #32
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Re: Why does cooling water exit above waterline?

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So, once again, how does the hose empty itself against the water pressure of the sea?
I think you agree that the hose is full of seawater up to the waterline.
Yes of course, but the sink waste is several feet inboard & above the waterline, so the waste water always has a head of say three feet or so on my boat. No pump is needed. I'm guessing that through hull is maybe 15 inches below the waterline. So the waste water pushes the sea water out of the hose.

I would accept that some waste water will remain in the hose which is why I flush it through with clean water if needed. In fact on my boat I also have a seawater hand pump at the galley sink so I could use that to save fresh water if necessary.

The hydraulic head of waste water in the waste pipe exceeds the pressure of the sea water in the hose.
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Old 13-03-2021, 11:05   #33
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Re: Why does cooling water exit above waterline?

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So, once again, how does the hose empty itself against the water pressure of the sea?
I think you agree that the hose is full of seawater up to the waterline.
So, for clarity, what you’re suggesting is if more water is added to the hose it will not drop to the waterline, but remain in the hose, above the waterline?
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Old 13-03-2021, 11:05   #34
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Re: Why does cooling water exit above waterline?

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So, once again, how does the hose empty itself against the water pressure of the sea?
I think you agree that the hose is full of seawater up to the waterline.
Gravity. If you have the sink above the waterline, and pour water into the sink, it will drain down to the waterline.
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Old 13-03-2021, 11:09   #35
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Re: Why does cooling water exit above waterline?

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Probably you are mistaken.
I have never seen kitchen sink on a boat to be drained underwater.
You would need a pump to press the discharged fluid into the sea.
My galley sink drains below the water line. No problems.

My AC also drains below water line. No problems.

My generator has a exhaust water separator with exhaust gasses exiting above the waterline and water below. Very very quiet arrangement.
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Old 13-03-2021, 11:22   #36
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Re: Why does cooling water exit above waterline?

Here is a link to the J105 information showing thru hulls. Not that it is not identified as an above the water line thru hull and does have a sea cock

https://j105.org/wp-content/uploads/...-Locations.jpg
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Old 13-03-2021, 13:58   #37
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Re: Why does cooling water exit above waterline?

Any raw water cooled machine inside a vessel should discharge used raw water above the wet line so that you have a visual conformation it is processing cooling water
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Old 13-03-2021, 14:25   #38
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Re: Why does cooling water exit above waterline?

I would never have thought a discussion about why one needs a pump to push out sink water (not needed) would actually become a discussion! No wonder Colregs discussions make it to 20 pages!
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Old 13-03-2021, 16:08   #39
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Re: Why does cooling water exit above waterline?

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I am sorry but I do not see what prompted that response (big AC unit). For details, they are 1500watt or less AC units, three in a 46' sailboat. I don't think its unusual, but again I am not sure what point led you to that conclusion.

Perhaps it is the noise? The pumps do move an excessive amount of water, but I have seen that on other boats as well. The designers do not add complexity to adjust water flow to the needed amount, just "lots of water".
Your set up is typical for individual units. 1 inlet/strainer & pump directed through a manifold to each unit with the outflow raw water from each overboard via a through hull usually convenient to the ac unit. Every boat in the South has a similar set up (unless they have split units in which case the through hulls are usually grouped together). Typically sailboats have the outflows a little higher ‘cause of heeling. Power boats usually a foot or so above waterline. These are high flow, low pressure systems so any outflow resistance may impede efficiency when sea temps & cabin temps start to converge. We just get used to it like we do the sound of lines creaking, wind in the rigging etc. just becomes background noise. If you are unlucky enough to bunk over or next to the AC unit or the fresh H2O pump - now that’s annoying.
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Old 13-03-2021, 16:50   #40
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Re: Why does cooling water exit above waterline?

Not an uncommon problem ,while I don’t recomend this it has worked verry well ,a T piece fitted into the engine exhaust down stream of the safety loop ,not elegant but it works.⛵️⚓️
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Old 13-03-2021, 17:19   #41
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Re: Why does cooling water exit above waterline?

A live aboard near my slip reduces the discharge water noise by lowering an old towel on a line such that the discharge hits it and then flows quietly into the the Bay. A solution for at anchor or a dock, not moving, but it seems to work well.
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Old 13-03-2021, 17:29   #42
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Re: Why does cooling water exit above waterline?

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Originally Posted by meirriba View Post
So, once again, how does the hose empty itself against the water pressure of the sea?

I think you agree that the hose is full of seawater up to the waterline.


Basic physics isn’t your strong suite?

I’ve never been on a boat with pumped sink drains when the sink is above the waterline.
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Old 13-03-2021, 17:37   #43
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Re: Why does cooling water exit above waterline?

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So, once again, how does the hose empty itself against the water pressure of the sea?
I think you agree that the hose is full of seawater up to the waterline.
Yes exactly up to the waterline.
Water flows downhill by the force of gravity. If the drain in the sink is higher than the waterline then the water will flow down the drain and through the drain hose to the sea. If the through hull is below the water line there will be water in the drain hose equal to the height of the level of the waterline outside the hull. If the boat is heeled over to the side where the through hull is below the water line on the side of the boat then water in the drain hose will be further up the drain hose then when the boat is level. If the boat is heeled over away from the side of the through hull then the water level in the drain pipe will be lower down the drain hose, but in all instances the water level in the drain hose will be equal to the water line. That is why most boats with drain through hulls have them located near the centerline at the bottom of the hull so it does not matter which way the boat is heeled over. The force of gravity is all that is needed to cause the water that is in a sink to drain out to a water line that is lower than the sink. One does not need to pump the water.

The sink drains the drain hose has some residual water in it up to the point which is equal in height to the waterline. Having residual water in the hose is of no consequence unless the hose ruptures below the waterline or it becomes disconnected from the through hull fitting.

Now if the sink was lower than the water line then the water will flow up the drain hose and flood the sink and the boat.
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Old 13-03-2021, 18:01   #44
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Re: Why does cooling water exit above waterline?

https://demonstrations.wolfram.com/P...own%20level%22.
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Old 13-03-2021, 18:02   #45
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Re: Why does cooling water exit above waterline?

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I would never have thought a discussion about why one needs a pump to push out sink water (not needed) would actually become a discussion! No wonder Colregs discussions make it to 20 pages!
Oh so going with that thread drift opportunity.

The water that is in the drain hose that is parallel to the level of the water line, must Give Way to the the water that is Making Way down the drain hose, but which water was earlier not underway, but rather Standing On [erhhh, make that In] the sink, being neither underway or making way. That assumes of course that the water that needs to drain is not Restricted in its Ability to Maneuver [RAM status], or otherwise impeded as to clear passage through a narrow channel. If the drain water is RAM status then the master of the vessel must right of way take all necessary substantial diverting actions to maneuver the drain water away from an allision with the obstruction.

There also being the matter as to the sink water on a boat that is headed downstream has the right of way over the sink water in a boat that is headed upstream. The upstream boats sink water must Give Way to the downstream sink water.

There also be the requisite sloshing signal noises as to stuck plumbing.

Lest we also not forget the MARPOL regulations.

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