That is steam coming out of a coal-fired power plant. It’s near where Palmer is fishing, along with several other leaders. If you will notice, that steam is pouring out at a right angle, which is indicative of a windy day.
That wind is an East wiind, possibly with a little North cut into it. Either way that’s the worst wind for getting across Charleston Bay and to the Cooper River.
It’s our guess they had a rough and tumble morning getting this way.