Big, white fire boat returning

I clicked this pic today. I believe this is our biggest "fire boat" returning to Zhuhai. The boat was a good 4km or 5km away when I took the shot. I used all the "lens" my trusty LUMIX FZ50 had, about 420mm. In the background is HK's Lantow Island. When I took this shot, the boat seemed to be almost dead in the water, and belching out big clouds of black smoke. Engine trouble, perhaps? I hope they made it back to port ok