Why do ships always seem to be pouring water from the side?

Question

I always see ships that seem to be shooting water from the hull, why do they do this?

Is it water sucked in by the engine for cooling purposes which is then pumped back overboard?

https://i.redd.it/ip5h2hn9qq791.jpg

In: 4419

Answer 1

The water you usually see spitting out of a ship is for engine cooling – it is usually raw water sucked in from somewhere else on the bottom of the ship, it goes through the engine (cooling), then it usually also goes to some heat exchangers which allow the heat put into the water by the engine to be used for other systems like hot water for showers, kitchen etc. before being piped out overboard, usually on the side of the boat but sometimes at the stern.

Water can also be from the bilges of the boat, or ballast. The captain or crew can turn on bilge or ballast pumps to either shift water within the boat or pump it overboard to raise the waterline (Or lower it) as required for stability or unsticking from a grounding incident. This water is usually not pumped overboard constantly – they’ll dump it for a bit then shut it off once it’s at the right level.

Water naturally seeps into many boat designs through the prop shaft seals. It typically comes in at a very slow drip, but if left long enough it can fill the bilge and require a long pump cycle to empty out. You can see some boats “peeing” at marinas even when no one is around, the bilge pump actuates via a float device like on a toilet. Failure of this system has sunk many a yacht just sitting at the docks waiting for the owner to come maintain it!