I have a 1979 O'Day 25 with a galley sink that will not drain. The boat is in the water. I can not trace where the clog is. There is tubing that comes down from the bottom drain of the sink and then goes to a T valve that routes one tube to the bottom of the hull the other end off to one side which routes to the starboard side mid ship of the hull above water line. I suspect the clog is in the valve can i pull this valve out or may this sink my boat with it being in the water? Is there anyone familiar with this setup or process i am a little nervous to tear into this valve. I have tried a plunger several times with no luck, just makes a mess. I thought of using some sort of snake but not to sure how well PVC tubing would hold up to this. Any ideas would be appreciated. Just FYI I think that it was coffee grounds dumped in sink while washing dish's that caused this.