NOAA Teacher at Sea
Aboard NOAA Ship Ka’imimoana
August 16-30, 2002
Day 18: Wednesday, August 28, 2002
The FOO (Field Operations Officer)’s quote of the day:
“Better three hours too soon than a minute too late.”
– William Shakespeare
Here are our observations at 0900 today:
Latitude: 3°39.88’S (into the Southern Hemisphere!)
Visibility: 12 nautical miles (nm)
Wind direction: 100°
Wind speed: 13 kts
Sea wave height: 4-5′
Swell wave height: 6-8′
Sea water temperature: 27.1°C
Sea level pressure: 1011.7 mb
Cloud cover: 2/8, Cumulus, Cirrus
Hurricane Genevieve lives!
Science and Technology Log:
I stayed up until I couldn’t keep my eyes open anymore last night. I finished the script and lesson plan for today’s broadcast with my graduate students in the Atmospheric Environment class. When I awoke at 0600, I realized that the fish bite test was already in progress on the fantail of the ship. I quickly prepared for my morning broadcast and then went outside to see if I could help place fish heads (mostly red snapper) on the lines that were being tested. The objective of the test was to qualitatively determine the fish-bite protection of a new armored mooring cable. The current cable that is used, nilspin, is very heavy while the cable to be tested is much lighter, but has a greater diameter. The test cable consists of a polyester core wrapped with electrical wires with up to two layers of special cloth armoring with a PE jacket. The cable diameter is ~221 mm. The test consisted of towing three 100 m cables (no armor, single, and double) simultaneously from the stern while the boat moved at 1-2 kts. Fish heads were attached every 3 meters to each cable. I was asked to take notes on the procedure since it was a new experiment and to use a multimeter to ensure that the lines were actually measuring electrical conductivity in case of a fish bite. Occasionally, I managed to assist with the deployment of the lines by helping place mesh bags alongside the line, opening the bag and inserting a partially frozen and slimy head of a fish, attaching the bag to the cable with wire ties, and then placing electrical tape over the wire tie and ends of the bags to keep them attached. It took approximately 2-1/2 hours to prepare the fish lines and deploy them. I really enjoyed it. There’s something exciting about having a group of people working together toward a common goal, especially when science is involved.
We started the broadcast soon after the fish bite test was running and I had the opportunity to interview a number of people on board who hadn’t been highlighted in a past broadcast. They were great! This was a more scientific webcast mostly focused on El Nino and the research conducted on the ship. I loved every minute and learned a great deal in the process. The video is 51 minutes long and can be accessed at on our videos page. Check it out when you have time.
I asked Lobo, our Chief Engineer, how portable water is created on the ship. He provided a great overview of the process. Seawater is converted into fresh water by vacuum distillation. In the end, the water is used for drinking, as process water, and for domestic purposes. The seawater to be distilled evaporates at a temperature of about 40°C (very low temperature for evaporation to occur) as it passes between the hot plates in an evaporator on board. The evaporating temperature corresponds to a vacuum of approximately 93%, which is maintained by the brine/air ejector. The vacuum serves to lower the evaporation temperature of the feed water. Having reach boiling temperature – which is lower than at atmospheric pressure – the feed water undergoes a partial evaporation, and the mixture of generated vapor and brine enters the separator vessel, where the brine is separated from the vapor and extracted by the combined brine/air ejector. The vapors that are generated pass through a demister where any drops of seawater that are entrained are removed and fall to the bottom of the distiller chamber. The vapors continue to the condenser where they condense to fresh water as they pass between cold plates. The freshwater that is produced is extracted by the freshwater pump and led to the freshwater tank. We can store approximately 3000 gallons of water on board.
I conducted a CTD test by myself for the first time tonight at 7:30 PM. Everything worked and we decided to test zucchini, a green pepper, a potato, and a round loaf of bread to see what happens to it when it’s submerged to the extreme pressure at 1000 meters below the water surface. When we finished the CTD cast where we sampled water at 1000m, 800 m, 600 m, 400 m, 200 m, 150, 100 m, 60 m, 40 m, 25 m, 10 m, and the surface, we brought the sampling cylinders up with the food. The potato looked and felt the same, the zucchini was squishy, the green pepper looked exactly the same but it had a crack on the side and was full of water. It must have burst on the way down and filled with water. In this case, the pressure would have been the same from the inside to the outside so no change in size took place. The bread looked like pita bread. It had been placed in plastic wrap, 2 zip-lock bags, and another plastic sleeve, but still managed to get wet. Interesting experiment.
Just after the CTD returned to the surface, I went to the starboard side of the ship to throw in an AOML, a device that measures water currents across the ocean surface (more on this tomorrow). AOMLs float away into the distance but transmit their data on a realtime basis. They are occasionally retrieved, but usually remain in the Pacific forever.
I am receiving all of your emails – thank you! It’s great to hear that your first week of classes is going well. I will highlight several of your questions in tomorrow’s log!
Congratulations to Steve Osmanski who knew that the term “knot(s)” is a unit of maritime speed goes back to the days of sailing ships, when speed was measured by throwing a wooden device called a “chip log” over the stern of the ship. The chip log had a line attached with knots spaced along it. When the log was thrown overboard, a timing device (usually a 30-second sandglass) was turned and the number of knots that passed through the user’s hand as the line unreeled during the 30 seconds was the ship’s speed in nautical miles per hour. It was reported to the officer of the deck as so many “knots.” The distance between knots in a log line is calculated at 1.688 feet for every second in your timing interval; so a 30-second log line would have knots 50.64 feet (50 feet, 7 and 2/3rds inches, just about). Many of you answered this correctly, but Steve was first!
John and I played Yahtzee tonight in the third round of the match. I managed to win again so I move into the semi-final round.
Question of the day: How long is the Ka’imimoana? Check out Teacher at Sea web site for all the details.
Closer to land, but wishing I was further out to sea…