Sink drain thru hull obstructed

[Redline452]

Our washdown/head intake blocked once- taking the hose off the toilet intake I saw... eyes staring at me. A small fish (species uncertain but definitely 1/2 “ in diameter) got sucked in up to the pump.

[Dave22q]

Wire / plumbers snake should do it. If it was mine I would relocate outlet above the W/L to avoid back pressure on the line. Otherwise expect frequent grease clogs. If there is a good reason lo locate a sink drain below the W/L I have not thought of it!

[Tom in Florida]

I bought a boat that had been stored at a marina in a swampy area. Several thru hulls were either slow or plugged. I ended up buying a mini "snake" from Harbor Freight and worked it from both directions until I could flush out the obstruction with hot water. In my case the problem was insect nests. I would not try a clothes hanger, as I fear it could be strong enough to either puncture the hose or force off a hose clamp. Anyways, now when I lay up the boat I get some wine bottle corks and stick them in the thru hulls to keep the insects out.

[kev_rm]

If you suspect it could be grease - Boil a large pot of saltwater. Fill Sink. Repeat.

[Suijin]

I agree likely just grease etc. Plunge it first, close the seacock, pour boiling water to fill, let sit a couple of minutes, open seacock and rinse. Repeat a few times. Much easier first step than disassembly and snaking and usually better results.

I do this once a month as preventative maintenance.

And don't put any sort of Drano like product in, even those fizzy tablets. They will take your bottom paint off around the thruhull pronto beyond what they'll do to the hose.