Mine are plastic hose so I would not use anything too aggressive. I get mostly airborne stuff and the occasional seagull. Two smaller drains sit inside the edge of the foredeck hatch
covers. A teak
rim around the inside of the molded deck
to both side aft corners where a 3/4 inch drains are located. Solids do collect over time and the dirt adds to make a solid clog. A 4 ft long piece of underground solid core
copper wire slides around just fine and will break it loose near the bottom. the heavy plastic cover over the solid copper slides well. For sticks and stones they probvably need to come out the way they went in. I have avoided those. The other 4 drains are larger hose with very short runs. The deck
fitting has a solid molded plastic plug
that acts like a screen
. Unless the trash buiilds up no much goes down that won't go out. For larger drains something like a 1/4 inch grid seems to work well on the larger drains.
If you get stain marks down the side below the scupper< insert a short section of small rope
that will alow the surface tension of the water
to hang on and drip from the end of the short rope
. You won't get stains down the side of the boat.
I like the plunger idea but I can't fit one to get a good seal. I can using my hand get a partial seal on the foredeck drains but I usually get a little spray on me from the back pressure if I use the hose at the dock
. The washdown pump cuts off if I try to use that.
For a steel
boat where things are at right angles I can see that something a little more aggressive might be required. Using a little caution and adding a little paitience can avoid the problems from "too big a hammer". When the plumbing
is just plastic hose and hose barb fittings with clamps you have to be careful.