If you are boating on a lake or any body of still water, the boat will automatically float downwind of the anchor when it is set. If you put the generator on the opposite end of the boat from the anchor line, it will be downwind and the wind should take the fumes away from the boat. I suppose you could also take a little power from the generator to run a small fan to blow the exhaust away from the boat. Lastly, a box to enclose the generator on all but one side would make it quieter. If the open side faced away from the boat, it would direct the exhaust out toward the open water.