inline breather for 1" Sink Drain
- Thread starter Little Dorrit
- Start date
Tranona
Well-Known Member
Yes, I thought I had been quite clear on that point, but somehow people want to overanalyse and bring in Pascal which is only partly relevant because the equilibrium point does not occur instantly, but slowly - exactly what the OP is experiencing. Probably made worse by his small bore pipe becoming even smaller bore through the seacock which actually has a step ideal for trapping any debris going down the pipe. Expect if he takes off the pipe he will find the 3/4" fitting partly bunged up making the flow even slower!
Lets face it sink drains on boats are usually inadequate because traditionally water was in short supply so the amount used in a sink minimal - or even in a bowl and chucked overboard. Modern boats where water is used more freely tend to have drains straight overboard rather than below the waterline so that they drain easily.
ghostlymoron
Well-Known Member
He doesn't mention that in his original question.
"Does such a thing exist? Is there any way of solving the slow or no drainage problem I'm having with my sink?"
Fr J Hackett
Well-Known Member
Virtually all sink drainage problems can be traced to crud in the seacock or pipe. It needs cleaning, to clean the seacock whilst the boat is in the water if you don't want water in the boat straighten out a metal coat hanger put a piece of pipe on the seacock that will extend above the waterline then poke the wire through the seacock and wiggle it about, you can try connecting the inflatable pump to the pipe and blow clearing the obstacle but I found that the wire works best.
Little Dorrit
Well-Known Member
Well done for highlighting the original question! Having read through all the replies and advice, some of which have been very helpful, others intersting (although not relevant). I am now inclined to think that the problem may well be a combination of issues; The boat does appear to have a relatively low freeboard and the sink sits close to (if not at) water level. I'm not sure therefore that there is any 'easy fix'. I know from experinece that most boats suffer to some extent from drainage problems although I have never owned a boat where it's such a peristent and annoying problem. My initial thinking was that if I could get some air into the pipe that would help but I'm now coming to the conclusion that would not work. However, while I may not be able to discharge the sink waste from the boat quickly perhaps an expansion chamber just before the sea cock (or wider diameter pipe) may help with the symptoms.
Fr J Hackett
Well-Known Member
Not if the pipe and seacock are full of crud, I owned a V27 and the sink used to drain OK apart from the odd blockage.
Tranona
Well-Known Member
No. he does not. That is the proposed solution to slow draining. Read what I have written. Drains below the waterline used to be common - but guess what - they are often slow to drain. Now more common to drain just above the waterline, and drain quicker. Possible downside is staining on the hull, but have to say never really had that problem.
Tranona
Well-Known Member
Read post#22. Your problem is explained there - narrow pipe, even narrower valve, lots of water in pipe to push out. You may well find the hose tail further blocked with crud because of the step where the hose attaches.
Larger diameter pipe will help but that means replacing sink outlet and seacock.
Kukri
Well-Known Member
Agree. As usual, Vic hits the nail on the head
Or in more detail:
1. Fit a domestic sink with a 38mm drain.
2. Take inch and a half (38mm) pipe to a diverter valve in the below decks manual bilge pump sump to pump line.
3. Use bilge pump to empty sink, potato peelings, congealed porridge and nasty dried curry scraps and all.
4. Job done, but if you are really keen you can add another non return valve in the bilge pump to skin fitting line.
You now KNOW that your bilge pump works, as you use it all the time.
ghostlymoron
Well-Known Member
Wouldn't potato peelings jam the pumps built in NRVs?
Kukri
Well-Known Member
I suppose it depends on the size of the peelings, but not in my experience - which extends to the useless knowledge (thank you, She Who Must Be Obeyed in a moment of absent mindedness) that a disposable nappy will pass right through a Baby Blake but not, alas, the seacock!
prv
Well-Known Member
VicS
Well-Known Member
ghostlymoron
Well-Known Member
This was mentioned in a earlier answer.
"3. Use bilge pump to empty sink, potato peelings, congealed porridge and nasty dried curry scraps and all."
Personally I don't peel potatoes on my boat.
"3. Use bilge pump to empty sink, potato peelings, congealed porridge and nasty dried curry scraps and all."
Personally I don't peel potatoes on my boat.
Last edited:
lw395
Well-Known Member
This.
stuff grows inside the skin fitting, then you feed it with plate scrapings etc.
A nice, full bore seacock and a length of garden wire, bit of old dinghy shroud or whatever.
If it's really bad, spin the wire in a cordless drill and move it up and down.
Same trick works on engine cooling inlet. Etc.
Kukri
Well-Known Member
Few of us do; I was being facetious, though I peeled a great many spuds when I shipped with Bill Tilman* - potatoes white cabbage and onions in deck lockers, all else tinned or dried. Advantage of going to cold places is the vegetables keep better.
* hope you spot the name drop
VicS
Well-Known Member
ghostlymoron
Well-Known Member
Going back to first principles, the velocity in the tube is proportional to the head ie height of water in sink above sea water level (if submerged, as mine is). Multiply by cross section area and coefficient of discharge will give you the flow rate. Bends and obstructions will reduce the effective head. The fact that the discharge point is submerged doesn't make much difference.
If the sink outlet is near the sea water level discharging above sea water level is not possible.
If the sink outlet is near the sea water level discharging above sea water level is not possible.
Little Dorrit
Well-Known Member
earlybird
Well-Known Member
The rather long pipe-length will introduce some extra friction, but worse, I'd think that the shape, as sketched, is ideal for solid debris to settle out and further impede the gravity flow.
