Seems to be fixed in latest DEV build :)

Note: One thing I noticed is some graphical issue atm at the heat source.

http://www.swe-gaming.com/fsx/files/2013-09/251654_2013-09-25_00003.jpg

Look on the left side. Its like the helicopter main rotor rotation is disturbing the heat image with colors of the sky.

Yep, the heat distortion is now totally gone...

I think the sound is not only fading away, the view behind the map stays on the exact place from the moment you hit the Map key. This is why you hear the helicopter fading away aswel you hear other sounds that might be in the area where you accessed the map. When you release the map the view warps back to your current view. If you access the map for a long time you'll see you have to render a lot around you. Correct me if I am wrong as I am not sure. But noticed some rendering issues on servers when accessing the map for a long time in a moving helicopter.

Just tried to reproduce this issue on latest DEV. Boat is not submerging, floats perfectly over the waves, tried to ride waves from every direction and didnt die. So I guess its fixed.