I sailed out of Seattle north about 2 weeks ago. I was heading directly into the wind. So I powered up the iron Ginny and proceeded past Elliot Bay Marina. As I approached at about a mile , I could see a large catamaran departing the marina and heading out. They headed across my intended path. They got out near some anchored freighters and reversed there course heading back towards the marina. I figured I’d pass behind them. I watched them pass my track. I looked down to check my chart and plot my track. I looked up and was surprised that the cat has again reversed their course and they were heading back across my track. And we were about to collide. I altered course crossed in front of them and looked at them they were in the salon looking a bit bewildered. I got the sense they had the right away because they were sailing and everyone were to get out of there way even if they just turned in front of them.