Galley sink drain issue

[nightowle]

'99 Bav 35E:  Any suggestions on why our sink would drain slow?  I've tried plunging, blowing with the wet/dry vac, removing the hose from the sink and sea cock end looking for obstructions.  Is it just because it drains below the water line?  Although, it seems the head sink drains in the same manner and no issues with that one.   

[Salty]

1. If it drains out below the waterline, then there is a possibility that marine fouling could be the reason why the water drains away slowly. I changed my underwater sea valves and skin fittings last winter from bronze to glass fibre, and on haul out last week, and for the first time ever I saw marine growth within the larger of the heads overboard discharges. (Guess there has to be a story there !!).
2. Another possibility could be that while your seavalve lever moves, maybe the valve spindle is no longer being gripped by the lever with the result that the valve is not opening fully. The valve handles are often made just from mild steel and corrosion over the years results in loss of material and grip.
3. Is it possible that the drain hose is partially blocked with a build up of food or fatty deposits. Occasionally I pour some bleach down and that helps to keep the drains clear.

[IslandAlchemy]

Stick the dinghy pump hose onto it and give it a few hard pumps.  If there's anything in it, this will clear it.

[Lyra]

You wrote that you disconnected the hose at both ends and it looks OK and unobstructed.
Connect it to the sink side, put the other side into a pail and open the water - see how it drains.
If it drains OK than look for a problem at the seacock area. If it drains slowly look for a problem at the sink outlet.

[nightowle]

Salty: I checked the underwater fittings last December when it was on the hard.  I'll give bleach a go.  I did try baking soda and vinegar.

Island A: I reversed my vacuum and gave it a good blast.

Lyra:  Good suggestions.  I'll try your approach.

I have to say I'm surprised the sinks drain under the waterline.  My previous boat had outlets just above the waterline.  Not sure if you guys have similar sink fittings, but mine have an immediate 90-degree turn underneath the sink.  Is that something boat specific for some reason?

[Salty]

Salty: I checked the underwater fittings last December when it was on the hard.  I'll give bleach a go.  I did try baking soda and vinegar.

Island A: I reversed my vacuum and gave it a good blast.

Lyra:  Good suggestions.  I'll try your approach.

I have to say I'm surprised the sinks drain under the waterline.  My previous boat had outlets just above the waterline.  Not sure if you guys have similar sink fittings, but mine have an immediate 90-degree turn underneath the sink.  Is that something boat specific for some reason?

I didn’t finish installation of the new GRP valves and skin fittings until February this year when the boat was last ashore, and at that time the fittings were all brand new, clean and entirely free from anything that might have attracted any marine organism to set up home. The boat was launched during the first week in April and just over a week ago at the end of September it was hauled out for the winter, complete with an uninvited squatter. So time was not really so important as opportunity in this case, and the GRP outlet may have been a more pleasant place to stay than the original bronze fitting. I wonder if bronze contains any copper elements within it?

Definitely worth taking things apart to determine where the blockage is located as Lyra suggests.

As for the right angle change of direction, all three sink outlets on my B36 have them, plus another ninety degree bend on each of the two which come from the galley sinks just before arrival at the overboard discharges. Both of the galley discharges and that from the heads wash basin are above the waterline while the toilet inlet and outlet and the shower drain overboard are all below the water line.

[Yngmar]

Before resorting to chemicals, try pouring a kettle or two of boiling water down there. Should kill most anything and also clear away any fatbergs and soapy deposits.

As for the drains being below the waterline, I rather like that. Boats with drains above the waterline often leave an unsightly foam carpet in the anchorage when doing their dishes.

We have plastic seacocks and thru-hulls and I coppercoated them all around and inside, right up to the ball valve. The only ones that see some growth are the ones not regularly used, such as the shower drain. A pipe brush from the outside clears that quickly though.

The elbow under the sink is there so that you can store more pots and pans underneath! A straight one would interfere with that

[Kibo]

Vision 46 has the sink on the centreline of the boat so the drain goes straight down below the waterline. In this case the lower the better for obvious reasons.

 It drains a little more slowly than my heads sinks which drain just above the water line so I guess that hydrostatic pressure has something to do with it. It is acceptable rate of drain though... not sure if that helps with perspective.

[Escapade]

In my B35E which is a couple of years older than yours I have a drawer underneath the sinks hence the need of the 90 degrees turn.
The discharge is not fast as a home sink but not too slow either, considering that the seacock is below the stove and the discharge pipe is long and features at least four 90 degrees turns. When compared to my earlier Beneteu Oceanis i can say it behaves about the same. I always thought it was because of the underwater discharge as my seacocks and pipes are new and there is very limited underwater growth in my area.

[nightowle]

In my B35E which is a couple of years older than yours I have a drawer underneath the sinks hence the need of the 90 degrees turn.
The discharge is not fast as a home sink but not too slow either, considering that the seacock is below the stove and the discharge pipe is long and features at least four 90 degrees turns. When compared to my earlier Beneteu Oceanis i can say it behaves about the same. I always thought it was because of the underwater discharge as my seacocks and pipes are new and there is very limited underwater growth in my area.

Yes, looks like ours are the same set-up.  I'll report back when I've had some further time to address this with some of these helpful suggestions. 

[Ricd]

On our B34 valley sink drains slowly immediately the plug is pulled. I give it a couple of seconds, then re-insert plug for a couple of secs then remove it again.....voila rapid draining. It’s been like that for 11years now. Don’t know why🤞

[nightowle]

On our B34 valley sink drains slowly immediately the plug is pulled. I give it a couple of seconds, then re-insert plug for a couple of secs then remove it again.....voila rapid draining. It’s been like that for 11years now. Don’t know why🤞

That's weird.....but I'll give it a try!!

[MarkTheBike]

On our B34 valley sink drains slowly immediately the plug is pulled. I give it a couple of seconds, then re-insert plug for a couple of secs then remove it again.....voila rapid draining. It’s been like that for 11years now. Don’t know why🤞

That's weird.....but I'll give it a try!!

Mine's the same, although I just lift the plug a little so there's a small gap all the way around. You can feel the sudden increase in suction and that led me to guess there's a syphon effect come into play. Not sure how but hey! it works and it's free - what's not to like? 

[Ricd]

On our B34 valley sink drains slowly immediately the plug is pulled. I give it a couple of seconds, then re-insert plug for a couple of secs then remove it again.....voila rapid draining. It’s been like that for 11years now. Don’t know why🤞

That's weird.....but I'll give it a try!!

It also happened on my previous boat, a Gibsea312, the vendor explained what to do and he had no idea why😇
Mine's the same, although I just lift the plug a little so there's a small gap all the way around. You can feel the sudden increase in suction and that led me to guess there's a syphon effect come into play. Not sure how but hey! it works and it's free - what's not to like?