Galley Sink Drains Annoyingly Slow

[Russ]

I just blast a garden hose (or washdown pump) through the cockpit drain or transom drain.
But after more time, I'm considering re-routing the sink drain more directly to a thru-hull. I know, another hole in the hull, but at least it would be more direct and less prone to clogging.


--Russ

[Boblee]

Would imagine that could be done but would probably need a swivel fitting so it could pivot to avoid getting an airlock but in practice ours at least is always in the bow end position, might get a stain down the side though depending on height.

[seahouse]

If you are going to open up the hole in the sink, you might still want to keep it at least slightly smaller than the inside diameter of the hose that it feeds. Logic is, whatever can pass through the sink hole, will easily also pass through the entire hose without getting stuck somewhere in the middle. I can't see that opening up the hole would have too much effect unless the hole is a lot smaller than the ID of the hose to begin with.

IIRC, a possible source of obstruction is debris (leaves etc) that has entered the hose via the hole in the transom well. A clog that is low enough in the line there (below the tee) will also stop the sink from draining. I have made a screen that stands above the hole, but also inserts into it to stop stuff from going into it, but still allows the well to drain even though debris has built up around it.

I would not say my sink drains quickly (it's the same as when new), but it is slowed somewhat by the length of the run, the diameter of the hose, and the water that stands in the loops (functioning essentially as a trap in a house would) and that depends on the current position of the galley. It drains at a rate that I would expect it to, considering all of that, and no obstruction. The catch is that the hose must be small enough to allow free movement of the galley without kinking, but that isn't quite large enough to allow the sink to drain quickly.

TFlight - is it possible you have an obstruction somewhere? Some grease or gunk has reduced the inside diameter of the hose?

-B.

[Kittiwake]

....I have made a screen that stands above the [transom well] hole, but also inserts into it to stop stuff from going into it, but still allows the well to drain even though debris has built up around it. ....

I agree with your above post seahouse. The only reason I am adding to it is to highlight the bit quoted above. I forget who first suggested rolling up a scrap of window screen to make a little funnel shape and stuffing only the narrow end into the transom well drainage hole (perhaps it was you) - but it is a darn good idea (and very appealing to a cheapskate canuck like me). The protruding 'fence' of screen excludes solid junk while permitting continued water drainage. I used a dab of epoxy glue to maintain the funnel shape so that periodically one can just pull it out and rinse it off before stuffing it back in.
Kittiwake

[Russ]

Anybody put a thru hull for the sink drain? I hate the long run aft to the T cockpit drain and then out the back. Seems more direct to go out the side.

Then I thought, what about the waterline? If the boat heels, will it fill the sink?

[Tomfoolery]

Then I thought, what about the waterline? If the boat heels, will it fill the sink?

Only if the sink went below the surface of the water you're sailing on, and that's some serious heeling.

[BOAT]

The sink drains lousy because it's not vented. If you own a motorhome this is a fundamental in RV plumbing, but not in boats.

I have seen mods here where people put a stainless sink in - I suspect if you do that correctly with a 2 INCH trap and a vent out the back your gonna have all the drain you want but you risk the chance of water backing up your vent pipe.

Lets see if anyone else has dealt with this - if not I'll take a stab at it (I have built several van conversions).

[RobertB]

I believe the vent is needed if you have a j-trap. Since most of us do not vent into a holding tank, we should not have a j-trap therefor no need for a vent. As far as obstructions, if you do not have a screen over the motor well cover, you can get a clog in the drain tee below it.

[finding41]

A PO of my boat installed a SS sink. It was a mess underneath with a 6" piece dropping strait down then the hose going along the floor and up to the through hull. It made the storage under the sink area a pain to use with the drain in the way.
I changed the way it's routed with a 90* right at the bottom of the sink going back and out of the way.
With the 26D we can heel far enough to get water in the through hull. I know this because the same PO installed a separate through hull for the bilge pump. No check valve... Of course it was a source of water when I heeled.....
My cockpit drain was plugged last spring but was easily cleaned out with my power washer.

My daughter wants me to use this smile.... The hat. Lol

[Tomfoolery]

With the 26D we can heel far enough to get water in the through hull. I know this because the same PO installed a separate through hull for the bilge pump. No check valve... Of course it was a source of water when I heeled.....

There discharge thru-hull must be above the water level no matter how steeply the boat heels. If it goes below the water line, and the bilge pump starts and fills the hose, when it shuts off the sea water will siphon right back into the bilge, causing short cycling of the pump. And of course, if the pump fails, it could sink the boat. Most bilge pump thru-hulls I've seen in the side of the hull are just below the rub rail.

[Russ]

I believe the vent is needed if you have a j-trap. Since most of us do not vent into a holding tank, we should not have a j-trap therefor no need for a vent. As far as obstructions, if you do not have a screen over the motor well cover, you can get a clog in the drain tee below it.

Yes, no holding tank so no vent or trap required. The biggest problem with the M is that the level of the sink drain is so close to the thru-hull that gravity doesn't do much. When my boat is in the driveway and tilted forward a little, the sink wont drain completely because the thru-hull was above the bottom of the sink.

The other problem is the diameter, the length of the drain hose (10') and that stupid T connector clogs all the time. Not a good design for quick draining.

That's why I'm thinking of a thru-hull right out the side by the sink.

--Russ