Kathleen Harrison: City on the Sea, July 20, 2011

Science and Technology Log

The Oscar Dyson is like a self-contained city for 35 people that floats on the sea.  All of the engine fuel and oil, food and provisions for the NOAA staff, ship’s crew, and scientists have to be brought on board while the ship is in port.  On this leg of the Walleye Pollock Survey, the ship will be out to sea for 19 days.  This presents several issues that must be solved in order for the people to be comfortable, and for the research to be performed.

First, fresh water is needed, about 100 gallons per person, per day.  For 35 people, that is 3500 gallons per day.  The ship has a storage capacity of 9000 gallons.  Do the math, and you can see that a daily supply of fresh water is needed.  Well, the ship has 2 water makers that convert sea water into fresh water.  Basically, the water is heated, vacuum pumped, and evaporated, then collected in the fresh water storage.  Salt does not evaporate, so it is left behind.  The evaporator uses the sea water to power an ejector pump (that creates the vacuum) and keep the unit cool. The brine (super salty water) created from the evaporation is sent overboard by the ejector pump.

Next, electricity is needed to power the galley appliances, run the washers and dryers, lights, computers, ship’s bridge instruments, and a host of other things.  The ship has 4 generators that are capable of producing enough energy to not only power the propeller, but also the whole electrical need of the ship.  The control panels for each generator are used to divert some of the power to each part of the ship, so that I can charge my camera battery, use my computer, or turn on the light in my room.

Another issue is the power needed to run the propeller.  For the 19 days the ship is out to sea, there are usually 2 generators running.  The ship’s computer decides which generators are needed for the speed that is required at any one time.  In heavy seas, or when more power is needed, a 3rd, or even the 4th generator will be brought on.  As generators are used, they wear and tear, so the computer determines what the most efficient use of them will be for each situation.  Everything can be manually controlled as well.  Every month or so, each generator needs an oil change.

They hold about 65 gallons of oil!  The used oil is kept on board until the ship docks back in Kodiak.  Also, about every 20,000 hours, each generator needs to be overhauled.  This is done by a team of mechanics when the ship is in port, during the off season.  About 100,000 gallons of diesel fuel is stored at the beginning of the trip, and 2000 gallons are used each day.

Now, since the Oscar Dyson is a biological research ship, the usually noisy generators have been quieted, so that the fish are not scared away.  One way to quiet a very large, 1600 hp engine, is to put it on a rubber mat.  Another way is to send the energy from the generator through a large box, which then converts it to electrical energy, and that is transmitted to the propeller by thin wires.  This reduces the vibrations in the hull.

To be an engineer on a ship, a person usually would go to a marine academy and obtain a degree in marine engineering.  During school and shortly after, time spent as an intern is valuable to gain experience.  Once the new engineer is employed on a ship, he or she would start at the bottom of the team, maybe as 3^rd engineer, depending on how large the ship is.  With experience, and management skills, the engineer could move up to 2^nd, then 1^st, then Chief engineer.  Of course, a ship’s engineer must love being at sea, and living on a ship.

Personal Log

We had a fabulous day for wildlife and scenery watching – bright sunshine (until 11:00 pm), calm seas, and close proximity to Kodiak Island.  I saw stunning rocky cliffs, Dall’s porpoises, and whales – probably Fin whales.  I was overwhelmed with the beauty and scale of Kodiak Island.