Hunter 380 aft vanity sink drainage

[djm32491]

Hi all, I'm new to this forum but have heard stories of the incredible wealth of knowledge on here so hopefully it's more than my own and a plumber friend of mine!
Here's what I know, my aft vanity sink drain of a 2001 Hunter 380 is fully clogged. After removing the hose from the sink and seacock, the snake ran clean and practically nothing came out (except water already in the line). After reconnecting to the sink and allowing water to run to the bilge, everything ran through fine, water seemed to get to the bilge without a problem. Even after testing the seacock and allowing some sea water to leak back through it ran just fine leading me to believe the seacock isn't clogged. Thinking everything was good, everything was put back together but the sink immediately wouldn't drain. I am at a total loss, it seems like something is blocking the drain but only when connected to the seacock, not sure if there's another line that's blocking this or what I'm missing. Any thoughts? Thanks for the help in advance!

 

[Ralph Johnstone]

it seems like something is blocking the drain but only when connected to the seacock,

Without being there, and assuming all is clear as you've said, I can only take a wild guess that your thru-hull is at a considerable depth below the water line. If your drain hose is full of air (as it would be after re-assembling) you are not able to set up the hydrostatic head needed to force the air down and out the thru-hull and allow the following water in the sink to flow.

If this is in fact the case, check the line for low spots (or even a "P" trap) and remove so that any air in the line can escape by rising up to the sink. The hose will then be filled with water and SHOULD have sufficient pressure to drain. Unless the hose is particularly dirty, there should be no unpleasant odours coming back with the air. And there is no sewer gas to contend with.

If not, we'll wait for plan B to come along :cry:.

 

[djm32491]

Ralph, not a bad idea. My through hull is almost exactly on centerline putting it about 2' below the waterline with the sink being about 2' above. Although I don't think the sink has a dedicated P-trap, it does seem to have some bends in the hose (many of which are unreachable leading me to this assumption) which may resemble a P-trap in operation. Any thoughts on how I could clear this trapped air without a dedicated means of venting?

 

[Ken Cross]

Water in the sink, open the stopper and use a plunger.
Ken

 

[Ralph Johnstone]

My through hull is almost exactly on centerline putting it about 2' below the waterline with the sink being about 2' above.

Ouch ................... with the thru-hull being 2' below the water line, this is probably why you can't drain the sink if the hose is full of air.

How to eliminate the air ? ? ? ...... now that's another problem. As Ken has mentioned, you could use a plunger to drain the sink but the sight of this may destroy the ambiance of a gourmet dinner aboard your boat :cry:.

The only solutions I can see are to either run the drain hose at a continuous slope down to the thru-hull (with no low spots) or install another thru-hull a few inches below the water line. Neither of these is going to be easy.

 

[artboas]

A few thoughts

Ouch ................... with the thru-hull being 2' below the water line, this is probably why you can't drain the sink if the hose is full of air.

How to eliminate the air ? ? ? ...... now that's another problem. As Ken has mentioned, you could use a plunger to drain the sink but the sight of this may destroy the ambiance of a gourmet dinner aboard your boat :cry:.

The only solutions I can see are to either run the drain hose at a continuous slope down to the thru-hull (with no low spots) or install another thru-hull a few inches below the water line. Neither of these is going to be easy.

Well, the question is, has this sink ever drained well?
On my 49, the through hull for the fwd sink is too close to water line, and it backs up frequently.
There may be a bunch of seaweed or something in your through hull
Here is how to clear it.
Get a scuba tank, and blow air down the drain hose.
Now, if you have an air lock issue, caused by there not being enough head pressure, then I have an alternate solution.
Instead of running the sink to a through hull, pipe it to a sump box. This will then need to discharge above water line.
There is an excellent sump box by whale, which costs about $90.
This is a guaranteed fix

 

[jsmac]

DJM, did you ever resolve this issue? I am having the exact same problem and not finding the solution. My sink used to drain perfectly, but over the past 2-3 years it has slowly stopped draining, and now almost not at all. I am concerned to use a plunger for fear of blowing something where it's not supposed to be, like blowing out a hose or clamp... I have not tried a snake yet but will do that this weekend.
Thanks!

 

[kappykaplan]

@jsmac , the OP hasn't been seen since Mar 2015!