52 nautical mile, new to me delivery trip home went well Sunday. Really rough crossing of the Georgia straight where for learning purposes, I ran into, down wind, and across the sizeable chop. Slowed down too, but this 27 mackinaw was much more stable at 20 knots. What a blast. When coming into dock, every time I shifted into neutral, I got a pretty weird and pretty loud noise, very much like a bilge pump sucking air. As soon as I shifted into forward, or reverse, it stopped immediately. I got docked, and turned off the engine, and opens the engine hatch and got smoke, and a horrible clutch/brake smell. Today I checked the transmission fluid, and found it full, not smelly, and clear. Turned the engine, and shifted from neutral, forward and reverse, and got no funny noises, and proper engagement in and out of gear..........any thoughts?