Sea Cock Advice

[PuffTheMagicDragon]

Just thinking aloud.
Would it be possible to fit a bottle trap like we have at home? Any debris will likely be trapped and may be easily removed if/when necessary.

 

[sailaboutvic]

We just use these traps that you put in the waste so nothing can go down the waste . Works ok for us, just mean you empty after each time you wash up .

 

[PaulRainbow]

The hose looks to be a fairly small diameter. Would it help, by preventing airlocks, if a larger size could be used? Feasibility my depend on the sink drain fitting.

It's 3/4". I get the impression from mine (same size, but without elbows) that at times it does airlock in some way, rather than block (i try not to let much other than water down the plug), which is why sticking my finger in the plug hole works. It allows a little water to escape to sea and removing my finger causes a bit of an inrush that gets the water flowing again.

It's an interesting idea to use bigger pipe. Perhaps a 1" hosetail on the valve and a sleeve at the plug hole to adapt to 3/4" might help. There would be a bit more wight of water at the valve. Who knows.

 

[pvb]

It's an interesting idea to use bigger pipe. Perhaps a 1" hosetail on the valve and a sleeve at the plug hole to adapt to 3/4" might help. There would be a bit more wight of water at the valve. Who knows.

The pressure would be the same, regardless of the pipe diameter.

 

[PaulRainbow]

The pressure would be the same, regardless of the pipe diameter.

One foot of 1" ID hose holds a greater weight of water than one foot of 3/4" ID hose.

 

[pvb]

One foot of 1" ID hose holds a greater weight of water than one foot of 3/4" ID hose.

It might do, but the pressure at the outlet is identical.

 

[PaulRainbow]

There would be a bit more wight of water at the valve.

The pressure would be the same, regardless of the pipe diameter.

One foot of 1" ID hose holds a greater weight of water than one foot of 3/4" ID hose.

It might do, but the pressure at the outlet is identical.

I sometimes wonder if you post just to argue ?

 

[pvb]

I sometimes wonder if you post just to argue ?

It's not easy to explain, but you'll just have to trust me that the pressure at the valve is the same, regardless of the pipe diameter. I studied fluid dynamics at uni, and I'm sure.

 

[VicS]

The pressure would be the same, regardless of the pipe diameter.

One foot of 1" ID hose holds a greater weight of water than one foot of 3/4" ID hose.

It might do, but the pressure at the outlet is identical.

I sometimes wonder if you post just to argue ?

But he is right.

It's not easy to explain, but you'll just have to trust me that the pressure at the valve is the same, regardless of the pipe diameter. I studied fluid dynamics at uni, and I'm sure.

My thinking is that there is a pressure at the outlet due to the depth below the surface, Initially the water level in the internal plumbing will be the same so the pressure in the outlet due to this will be the same as the pressure outside. With no pressure differential there will be no flow .

If the water level in the internal plumbing is raised, due to water discharging from the sink, the pressure at the outlet, due to the water in the plumbing, will be greater than that outside. Water will therefore flow outwards until equilibrium is restored.

If the hose is of a small enough bore it could become air locked and rather than continuing a continuous column of water contain a series ot slugs of water separated by slugs of air. Water will then not flow out to waste if the combined height of all the water slugs is not greater than the depth of the outlet because they will not exert force , at the outlet, greater than that due to the depth below the surface.

It wont ( does not) happen with 1" bore hose, I doubt if it will happen with 3/4" bore hose but it might with 1/2" hose especially with the horizontal section.

 

[pvb]

But he is right.

Thanks, Vic. As you say, the pressure at the outlet is proportional to the head of water, regardless of the pipe size.

 

[rogerthebodger]

I've only used it on my galley sink, but i guess it would work on most waste blockages Roger.

You are not getting me

Are you married BTW ?

 

[rogerthebodger]

Thanks, Vic. As you say, the pressure at the outlet is proportional to the head of water, regardless of the pipe size.

I agree pvb is correct its the head of water that gives the pressure not the volume.

When you dive in the sea to 10 meters you will experience the same pressure it you dive to 10 meters in a swimming pool of the same sea water.

Its the density of the fluid that will change the pressure for the same head of fluid.

As I posted early what you need it to position the seacock directly below the sink outlet then you will have no more problem.

I did this when I had the same issue when I first launched my boat.

 

[RichardS]

The pressure would be the same, regardless of the pipe diameter.

That's very true ..... but the mass of water would be greater. Perhaps Paul meant mass rather than weight?

(Just thought I'd throw that out in the spirit of goodwill to all men)

Richard

 

[VicS]

That's very true ..... but the mass of water would be greater. Perhaps Paul meant mass rather than weight?

(Just thought I'd throw that out in the spirit of goodwill to all men)

Richard

but weight is only mass x g

although the value of g will depend upon which planet PR is on

 

[RichardS]

although the value of g will depend upon which planet PR is on

People often ask me the same question.

Richard

 

[PaulRainbow]

You are not getting me

Are you married BTW ?

I am, i fear you didn't get me Roger.

 

[rogerthebodger]

I am, i fear you didn't get me Roger.

May be so, I can see strange things or I am strange but as they say up north There's nowt as funny as folk .

 

[PaulRainbow]

May be so, I can see strange things or I am strange but as they say up north There's nowt as funny as folk .

I did deliberately type some of my replies as "double entendre", perhaps i should have included smileys.

That does not mean that you are not strange though Roger

 

[Tranona]

Thanks, Vic. As you say, the pressure at the outlet is proportional to the head of water, regardless of the pipe size.

And that is precisely why all sink drains that exit below the waterline are slow to drain, requiring the use of plungers, fingers, boiling water etc to function (badly). The deeper the exit under water the slower the drain.

The OP's is particularly bad piece of design particularly with 2 right angle bends and a horizontal run, coming from what was perceived as one of the country's top builders - who clearly had no idea of the basic physics.

The only thing in favour of this bad design is that it has produced so far 6 pages of mostly good humoured banter, while also giving the poor owner of the boat good advice as to how to solve his problem - which of course should never have happened in the first place.

 

[rogerthebodger]

The deeper the exit under water the slower the drain.

Could you please give me a technical explanation for your statement above,