NOAA Teacher at Sea
Wes Struble
Onboard NOAA Ship Ka’imimoana
July 8 – August 10, 2010
Mission: Tropical Ocean Atmosphere (TOA) cruise
Geographical area of cruise: Equatorial Pacific from 120ΕLongitude to 95Ε Longitude
Date: 14 July 2010
Weather Data from the Bridge
Cloud cover: 6/8 (75%) with stratocumulus clouds
Visibility: 10 nm (nautical miles)
Wind: bearing 330Ε at 14 knots
Atmospheric Pressure: 1012.0 millibars
Temperature: 24.6ΕC (76.3ΕF)
Wave height: 1 – 2 feet
Science and Technology Log
The last few days I have spent some time up on the bridge of the Ka’imimoana. Ensign Linh Nguyen, one of the NOAA Corps officers, showed me around and explained some of the equipment. They have three general types of equipment available on the bridge which I will categorize as: communication, propulsion, and navigation.
The communications system first includes intra-ship lines. These are mostly carried out by an intercom type system. Each major area of the ship (including each stateroom) is connected to this intercom system by a phone that permits communication with any other part of the ship. The ship also has numerous hand-held radios available for use when one is not near a phone. In addition, the bridge has both inter-ship and ship-land communication capabilities. The KA (short for Ka’imimoana – Hawaiian for Ocean Seeker) also has access to the Iridium satellite platform for communication with land in addition to access to a satellite internet and internet VOIP system.
There are two types of propulsion on the ship. First, there are four large diesel engines that power a generator. This generator produces the electrical power that runs each of the two electric motors that drives the screws (propellers) located at the stern (rear) of the vessel. While moving through the harbor all four diesel engines are running sending power to the generators. When the ship is out at sea only three of the diesel engines are used. The ship can operate with only two engines in service for power generation but under this configuration the ship will cruise at slower speeds. The KA has two screws: port (the left side of the ship if one is facing the bow or front of the ship) and starboard (the right side of the ship if one facing the bow). Each screw runs independent from the other with separate controls on the bridge. The conning officer (the officer who is in charge of the bridge at any given time) can change course by turning the rudder (the most common way) or by altering the speed (rpm) of one of the screws (without using the rudder). The KA also has a bow thruster (also powered by an electric motor) that is mounted in a tunnel through the forward part of the hull. This thruster permits the conning officer to move the forward part of the ship port or starboard without the main screws driving the ship forward. The bow thruster allows more subtle and precise motion that could be used for docking or perhaps helping keep the ship over a precise location while collecting data at those particular coordinates.
The captain of the KA, LCDR (Lieutenant Commander) Matthew Wingate, described the navigation system of the KA as modern but not state-of-the-art. The ship has many redundancies built into its guidance system. Two radar consoles, three compasses (two digital/electronic and one analog), an AIS (Automatic Identification System), paper charts, a fathometer (sonar) and of course, binoculars and the naked eyes of those on constant watch. The radar system is quite fascinating. It has an adjustable range with the ability to scan out to almost 100 nautical miles. The system plots the projected course of the ship and the predicted course of other ships within its range using vector analysis. This information is necessary to be able to prevent (well ahead of time) any possible collisions that might take place if the ships hold to their current courses. In addition, it is possible to set a radar alarm range of a particular radius around the ship. If any object comes within that range an alarm sounds to alert the pilot of the danger.
While I was on the bridge there were three other ships registering on the radar monitor each traveling in different directions. The two digital compasses are mounted side-by-side and their readings (and the difference between the readings) are projected at the navigation console. Above one’s head and not far from the digital compass readout is also a standard magnetic compass. The AIS (Automatic Identification System) is probably the most fascinating device I have seen on this ship. It is similar to radar readouts but provides much more information. First, one needs to understand that when ships are at sea they continuously send out a signal that provides identification information. The AIS receives this information and plots the locations and courses for these ships in addition to the location and course of the KA. All of this information is superimposed on a digital nautical chart that shows islands, shoals, exposed rocks, depth contours, and continental shorelines that can be adjusted for different scales. At the right margin of the AIS screen is listed navigation information such as the latitude and longitude of the ship, course bearing, ship speed in knots, and other pertinent data. Besides the course plotted on the AIS the conning officer also plots out the ship’s course on a paper chart and cross-checks it with the AIS. The fathometer shows the depth of the water under the ship and therefore the contours of the ocean bottom. This information can also be cross-checked with the charts and the AIS to make sure that they all agree. Last of all there is always someone on the bridge keeping watch on the instruments and the horizon verifying what is on the charts and monitors with what they see with their eyes through the binoculars.
Personal Log
I have enjoyed walking about the ship during the day taking pictures and looking at the various types of equipment on the decks. I hope to describe these in later logs. I was on one of the lower weather decks this morning simply taking in the views of endless water in all directions. When the sun is out the water has a deep blue color with a very slight greenish tint. As the bow cuts through the water, waves and foam are pushed out creating a variety of tints of blues, greens, and white. It is beautiful indeed.
While I was watching, out popped a flying fish! It jumped out near the bow wave and glided about a foot off of the water for about 50 yards or more. When it would hit a wave crest it would boost itself with its tail and go a little farther. I stayed at that location for another half hour and watched many others, some small groups, and several large schools of 50 or more “fly” at one time. The longest “flight” was about 100 yards with the fish in the air maybe 5– 10 seconds. I would not have even thought to look for one of these fish. Like most children I had read about them and seen pictures of them when I was younger but never really thought that I would ever see one. What a great surprise.
Being from Idaho’s northern latitudes, the sun only gets approximately 67Ε above the horizon on the Vernal equinox. It has been interesting to have the sun literally directly overhead during a portion of the day. This, of course, produces few areas of shadow to get out of the sun’s harsh equatorial rays. When we left San Diego it was in the mid to lower 60’s but as we have worked or way south (about 200-250 miles per day) the temperature has been slowly rising. I am told that it will soon be very hot and humid so I should enjoy this mild weather while I can.
New Terms
I have learned a few new terms for parts of the ship that might be helpful for future logs. Deck – refers to any floor on the ship. I would refer to the floor of my stateroom as the deck. Bulkhead – this refers to any walls on the ship. I am required to keep the deck and bulkheads of my stateroom clean. Head – this refers to a bathroom on the ship. I have a head that I share with a crew member in the stateroom next to me and there is also a “public” head available on this same level. Aft – can mean in back of, behind, or toward the stern of the ship. Forward (sometimes simply fore) – can mean in front of, in front, or toward the bow of the ship.