The moonpool

Generally-speaking, holes in ships are A Bad Thing, but in the center of the R/V Seward Johnson there is a hole, a really big hole, that’s both deliberate and critically important.  It’s called a moonpool and it’s used to deploy the device that allows the Com-Track (see previous post) to talk to the sub: the transducer.  This acoustic tool (basically a combination speaker and microphone) could just be dangled over the side, but the hull of the ship would interfere with the signal, so they lower it through the moonpool well below the ship.  It’s a lot like putting up an antenna, only upside down.  As I stared down into the blue glow, Sully the Com-Track officer was using the transducer to speak to the sub pilot, 800ft further down into the depths below…

PS - If you’re wondering why the water doesn’t rush up through the moonpool it’s because the water in the moonpool is level with the surrounding sea level, so there’s no pressure to push it up into the hull.