High speeds on the high seas
March 25, 2000
By Dr. Dan Fornari

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partly cloudy weather

Blue skies, scattered clouds
84.4°F (29.1°C)
Latitude: 14 deg 26.5’N
Longitude: 104 deg 21.3 ’W
Wind Direction: NW
Wind Speed: 7 Knots
Sea State 0
Swell(s) Height: 3-5 Foot
Sea Temperature: 83 °F (28.3°C)
Barometric Pressure: 1015.0 MB
Visibility: 10-25 Nautical Miles

what's to eat today?

Coffee Cake
Dry Cereal
Fresh Fruit

Mushroom Soup
Okra Gumbo
Salad Bar
Fresh Fruit slices

Pinto Beans
Mexican rice
Cauliflower Combo
Salad Bar
Fresh Strawberries and Angelfood cake

Sunrise saw RV Melville steaming at nearly 14 knots through glassy seas on a heading of 189°, just west of South. The ship’s speed overnight was more than 1 knot faster than normal. Sea swells were low, so the ship did not have to battle against waves. What’s more, a surface current moving in our direction actually helped push the ship south.

Scientists on board need to calculate how long it takes to get to each site where seafloor surveying will take place. To do this, they need to know the distance they have to travel (by measuring it on a map) and the speed the ship is going. They find the ship's speed using the Global Positioning System of satellites, which calculates ship positions and speed very accurately. With these two pieces of information, they can use a basic mathematical formula that everyone needs to know: T=D/V, or Time equals Distance divided by Velocity. If you know how fast you are going (your Velocity), and you know the Distance you have to go, you can always figure out the time it will take you to get to where you are going!

Onboard Melville this evening at 2200 hours, scientists received information from the ship’s bridge that the ship was 130 nautical miles from where it will stop to test the multibeam sonar system. We must make absolutely sure that the sonar system will collect extremely precise and reliable measurements. The ship’s average speed today has been 13.3 knots (nautical miles per hour). So we calculated that we will arrive at our first stopping point in 9 hours and 48 minutes, or at 0748 hours on Sunday, March 26. You do the math and see if we are right.

During Expedition 3 we will tell you when we start transits between our survey sites, what the distances between sites are, and what we expect the ship’s velocity, or speed, will be. We ask students to use the Mail Buoy to send us their estimates of when we will get to our next survey sites. We will post replies on the Mail Buoy.

Today there was lots of activity on board. Scientists began to organize their watch schedules: 4 hours on watch and 8 hours off watch. At the same time, technicians were preparing the DSL-120 sonar for survey operations. Technicians from Scripps Institution of Oceanography were also explaining the ship’s different echo sounding systems and how to keep good logs, or records. Keeping good records is critical for any experiment, whether it is in a lab or in the ocean. The ship’s crew was busy keeping all the systems on board working well. From the engine room to the galley to the bridge, everyone was working hard. At a fire and boat drill this afternoon, scientists learned what to do in case of an emergency at sea. We will have such drills each week.

Scientists and technicians continued preparing for the start of survey operations into the night. Everyone is looking forward to starting the seafloor mapping and seeing firsthand evidence of volcanic eruptions on the seafloor.