Theresa Paulsen: A Vessel Built on Science, March 23, 2015

NOAA Teacher at Sea
Theresa Paulsen
Aboard NOAA Ship Okeanos Explorer
March 16 – April 3, 2015

Mission: Caribbean Exploration (Mapping)
Geographical Area of Cruise: Puerto Rico Trench
Date: March 24, 2015

Weather Data from the Bridge: Scattered Clouds, 27.0˚C, waves 1-2ft, swells 3-4ft, wind 11kts from 100˚

Science and Technology Log

A ship like the Okeanos Explorer demonstrates the connection between science and engineering to the n^th degree.  Every room that I visit and every person I talk to can illustrate scientific applications.

Consider the galley I introduced you to in my second blog post.  On a three-week cruise with no access to a grocery store, how are the cooks able to serve fresh fruits and vegetables?  I assumed that they would have to serve canned or frozen foods as time went on but that is not the case.  The Chief Steward, Dave Fare, tells me that he or a member of his crew, goes through the produce each morning to pick out anything that is past its prime so that the any ethylene emitted by the offending overripe items won’t affect the other fruits or vegetables. So far the food has been fabulous so it must be working!

Then of course, you have the clean up where dishes are rinsed, washed, rinsed again, and then sanitized in a high temperature dishwasher to kill off any harmful bacteria.  Biology in action. They occasionally add beneficial bacteria treatments to the drains to help break down any organic matter that makes its way into the drain pipes.  This reduces the unpleasant smell of decaying matter and makes the water cleaner.

Where does that water go?  I took a tour to find out.

The water that goes down the drain or gets flushed goes through an onboard wastewater treatment process similar to one used by a city but in miniature form. It is macerated (ground up), filtered, and then treated with just enough chlorine to kill harmful bacteria before leaving the ship.  The ship’s First Assistant Engineer, Ricardo Gabona, told me that the effluent (water leaving the ship) looks as clean as the seawater we are sailing on with less than 15 ppm total dissolved solids.

How do we survive without additional freshwater for drinking?  We don’t have to!  We are actually drinking seawater – after it has been distilled.  It is a pretty cool process.  The water used to cool the engines, absorbs enough heat to raise the temperature to about 180˚F.  Using a vacuum, the pressure of the water from the engines is reduced so that it boils at temperatures as low as 150˚F.  Next the vapor is condensed.  There you have it – distilled water!  That is great energy conservation in action!  The water then has to be cooled, before heading to the faucets with a heat exchanger.  No need for a water heater – the engines do the work!  The distilled water is also filtered and run through an ultraviolet light tube twice just to be sure to kill off any remaining microbes.  The distillers can make water at a rate of about a gallon per minute.  There are two of them on the ship.  So can you calculate how long it would take them to make enough water for the maximum 46 people on board, each using 50 or more gallons per day?

In order to draw in relatively clean sea water, the ship must be at least 20 miles from shore, according system’s manufacturer, to avoid contamination from erosion and runoff. For us this means we need to transit north periodically to make water, disrupting our planned mapping route. Water conservation is a priority on this cruise to avoid that as much as possible.

Check out our mapping progress!  You see, the vertical paths were taken when we needed more water.

What about fuel?

According to Ricardo, the ship was originally built as a submarine hunter during the cold war.  It’s mission was to listen for and locate Russian submarines.  It carried a crew of 24 sailors for 6-9 months at a time. NOAA took charge of the ship in 2004 and by 2008 had modified it to become the exploration vessel it is today.  Some of the fuel tanks now serve other purposes.  Currently the ship can hold 149,000 gallons of diesel fuel! The ship now has 26 crew members, but also now hosts teams of up to 20 scientists, which requires more power and energy.   Still the fuel can last more than 2 months.  The ship will need to be refueled before heading to the Panama canal en route to the Hawaiian Islands.

Why diesel?  It is a very safe fuel for ships, since it won’t ignite at standard temperatures and pressures.  But diesel can be dirty and can contain water, both can interfere with engine performance.  You don’t want to have engine trouble when you are out at sea.  So the fuel is cleaned with a fuel purifier and water separator that use a centrifuge to  separate the fuel from the contaminants based on density.  The fuel entering the engines goes through this process multiple times to ensure the engines are getting very clean diesel fuel.  As a result, you don’t see or smell the exhaust from the combustion.

Of course all of this fuel is heavy, as it is used, the ship would get lighter and lighter making it float higher and higher.  This would be a problem for stability.  As any object’s center of gravity rises higher, the object becomes less stable and more likely to topple.  You do not want your ship to topple!  So you need to replace the fuel as you use it with ballast water.  The fuel and ballast tanks are located all around the ship.  As the fuel tanks are emptied and water tanks are filled, the engineers must consider the balance of the vessel, ensuring the mass is distributed properly for optimum performance and stability in the water.

Personal Log:  

I am loving this adventure.  I am mesmerized by the massiveness of the ocean.  I love looking out at water as far as I can see with only a ship or two in the distance every now and then.   I could watch the water for hours on end.  You see interesting things when you are really looking, each one giving you cause to wonder.  Consider the interesting birds that fly by.  What are they?  Where do they call home?  Why do they like to fly by the ship?  Why do flying fish fly?  Are they finding insects that I can’t see, or are they evading predators?   Where do all the seaweed patches floating on the water come from?  What kind of seaweed is it?  Is it edible?  Do they grow there at the surface, or are they floating debris carried out to sea, or is it a combination of the two?

Let’s start with the birds.  Lieutenant Emily Rose, Operations Officer, told me they are brown boobies.  Take a look at these photos taken of the bow of the ship.

Did You Know?

According to Wikipedia, brown boobies nest in large colonies in tropical areas like the Caribbean and the Gulf of Mexico.  They very good fliers that can plunge for fish at very high speeds, but they are clumsy at take off and landings as we observed on the bow this morning.  One of the birds tried to land on the railing and slipped. Junior Officer Bryan Pestone had to help him up and over.  He flew away for a short time and then returned.  My guess is they use the vantage point of the ship to watch for small fish and to preen themselves.

I’ll let you know what I find out about the seaweed and flying fish in future blogs.  ¡Hasta Luego!

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