Susy Ellison, Aaargh Matey, How’s Your Number Sense? September 22, 2013

NOAA Teacher at Sea
Susy Ellison
Aboard NOAA Ship Rainier
September 9-26, 2013 

Mission:  Hydrographic Survey
Geographic Area:  Cold Bay, Alaska
Date:  September 22, 2013   

Weather:  current conditions from the bridge
GPS Location: 55^o 15.190’ N   162^o 38.035’ W
Temp: 8.6C
Wind Speed: 10 kts
Barometer: 1008.3mb
Visibility: 10 miles

You can also go to NOAA’s Shiptracker (http://shiptracker.noaa.gov/) to see where we are and what weather conditions we are experiencing.

If you want a detailed report of weather in our area, check out this link and hover over Cold Bay: http://pafc.arh.noaa.gov/index.php?index=bering   

Science and Technology Log

THE FINE ART OF STARING AT A STICK!

 What would you think if you saw someone bundled in warm clothing, sitting in an office chair on a pier with a pair of binoculars, a watch, and a clipboard?  Are they counting waves? Counting birds?  Keeping track of the clouds or the wind speed?  In my case it was ‘none of the above’; I was watching a measuring stick, taking measurements every 6 minutes over a period of 3 hours.  Why would anyone want to sit in a chair on a pier and stare at a stick for 3 hours?

The answer, of course, is science! Now, this wasn’t just any sort of stick.  This tide staff was attached to an automatic tide gauge that the crew of the Rainier installed during their last visit to Cold Bay in August.  That gauge has been recording tidal data that is used during their hydrographic survey work.  But, as with any automatic data-gathering device, it is critical to field check its accuracy, both in measuring and reporting the data.  The gauge measures the depth of the water column at 6-minute intervals, using the pressure of the water column as a proxy for that depth (deeper water exerts a greater pressure on the subsurface opening of the gauge—for a more in-depth explanation, you can check out my blog from September 13th).  My job was to stare at the staff for a period of 1 minute every 6 minutes, and determine both the highest and lowest height of the water lapping at the markings on the stick.

This might sound easy, but it wasn’t quite so simple.  The wind was howling and the waves were bouncing—it took a little practice to make what I hoped was an accurate estimate of both the high mark and the low.  After each observation period I recorded these numbers on a spreadsheet and then spent the next few minutes watching the birds that were flying and landing on the water.  Then—back to the stick!  The tide was dropping with each observation and the winds died down enough to make it a little easier to read the high and low points on each successive 6 minute interval.  By the 10^th observation I had it figured out!

The data I collected was matched against data from the tide gauge for that same time period.  I was pleased to see that my observations matched those of the gauge.  Apparently, both of ‘us’ are good observers of tidal changes.  Now I have one more skill to add to my resume!!

AAARGH, MATEY—HOW’S YOUR NUMBER SENSE?   APPLIED MATH ON THE HIGH SEAS  

It would be hard to find an aspect of life aboard the Rainier that doesn’t involve number sense or math.  This ship’s daily operations run like clockwork; breakfast from 0700-0800, Safety Meeting and deployment of the launches at 0800, lunch from 1130 to 1230, launches return at 1630, dinner from 1700 to 1800, etc.  Pretty simple numbers to deal with, but numbers, nonetheless.

That’s just the start of your applied math tour of the high seas. Maybe you have to figure out how much diesel fuel the ship has onboard.  Since the Rainier uses 20,000-40,000 gallons for each leg of its cruise, it would be pretty horrible to run out before you reached port.  The ship’s tanks can hold around 100,000 gallons of diesel and are usually filled to within 95% of that.  Unlike your car, there’s no fuel gauge on this ship.  So how do you figure out how much fuel is in the tank?  It’s time for some simple, yet essential math. First, you need to know the volume of the fuel tank.   Get out your math books and find that formula.  Then, you take what is called a ‘sounding’—you bang on the tank to determine the level of fuel.  Not too complicated, but certainly a skill that takes some practice.  So, now you know the total volume of the tank as well as the actual height of your fuel; if you figure out the volumes for each and do some subtraction, you can find out what percentage of your total fuel is still in the tank.

We might all be better at determining volume and percent if we had images of a fuel tank on the dashboards of our cars instead of a linear gauge reading ‘E’ to ‘F’! What about drinking water?  The Rainier uses a distillation system to create fresh water from seawater.  There are tanks down in the engine room where seawater is heated to the boiling point.  There’s a little more math and science in this process—the pressure in the distillation tank is lowered, to lower the boiling point (if you’ve ever camped at a high elevation you might notice that water boils at a lower temperature—your tea might not be quite as hot when it’s boiling) so the water doesn’t have to be heated quite so much to get it to boil.  This steam is captured in the upper portion of the distiller and cooled using cold seawater that flows through pipes.  The condensation from cooling is captured, filtered to remove any impurities, and distributed as fresh water to all onboard.  The ship uses around 2500 gallons of water each day.

If you’re running the galley it’s essential to calculate how much food you’ll need for each leg of the trip.  No one wants to do without their morning eggs if your multiplication is off and you ‘forget’ to buy a few dozen.  Taking a recipe that is designed to feed 8 people and ‘upsizing’ it for 48 people takes a bit of mathematical manipulation.  Just planning a menu for a three-week journey takes some mathematical thinking as you visualize the weeks, days, meals, and individual ingredients needed for those meals.  You have to factor in a few variables; which foods have the longest shelf life, when do you have to switch from fresh to frozen or to canned foods, how much food does the ‘average’ person eat, and what about all those people with food allergies or preferences?  While this might not sound quite as earth-shattering as using a detailed computer program to concatenate multiple data files, this is math that counts—especially when you’re feeding a boatload of hungry crew.

So now it’s time to consider the math used to pilot the ship.  Think about degrees in a compass bearing and the need to do some rapid mental math as you’re steering a 231-foot ship through some very tight spaces.  Quick—take a course of 340^o, now look ahead and get ready to change your bearing to 28^o.  Rainier’s draft (how deep it sits in the water) is around 16’.  Will the channel be deep enough?  What if you’re traveling in a supertanker, one that might be over 400’ in diameter and have a draft up to 80’ deep?  If your ship is that big, you need to scale up on your mental math calculations as you’re searching out appropriate harbors and routes! What about tying up the ship when we’re in harbor? Did you remember to learn something about vectors before you stopped taking math classes?

When we were at port in Cold Bay, the winds were expected to increase in strength and to shift so that they would be coming out of the west.  Since the pier was oriented perpendicular to the predicted wind direction, our Chief Bo’ sun, Jim Kruger had to do some mental calculations of the angles needed to secure the ship to the pier and keep it from bouncing too much.  He doubled and even tripled some of the lines, taking into account how the winds might move the ship as well as the strength of each line.  It takes some stout lines to hold this ship; each 300 ft. line is 1” in diameter and has a tensile (breaking) strength of 164,000 lbs.    Vector angles were equally important as we pulled away from the pier in a 50-knot wind.  Just pulling up our gangway with a crane required some careful mental calculations of where to place lines to steady it as it rose through the air and was lifted onboard. If your mental math and visualization skills were wrong, you might be rewarded with a wildly swinging piece of metal.

How about all that hydrographic data collection; there’s plenty of opportunity there for some pretty extreme mathematical calculations.  You might even wish you had taken a class in calculus—or a few classes!  But there are also plenty of times that some basic number sense and arithmetic come in mighty handy.  As I sat on the pier watching the tide gauge, one of the tasks I had to do was to calculate the average between high and low water marks on the tide staff.  Not such hard math, but it’s a good skill to be able to do averages in your head while your hands are getting cold and the wind is howling.  The tide gauge calculations were referenced to Coordinated Universal Time (UTC). This has been our world standard since 1972, and is referenced to the 0^o meridian at Greenwich, England.  It is precisely measured using an atomic clock.  You might also hear it referred to as Zulu Time.  Even airplanes use this time designation.  This way, there is no ambiguity about whether you are in daylight savings or standard time, or your time zone.  When measuring tides or collecting information about water chemistry using the CTD, or calculating the launch’s daily gyrations, it is important to reference everything to the same time standard.  Since the Rainier is on RST (Rainier Standard Time), the calculation gets even more important because we are in the Alaska time zone, but have set our clocks back one more hour to give us more daylight working hours).

Just in case your brain hasn’t been addled by all this talk of mathematics, there’s one more concept that might come in handy here on the high seas—a sine wave.  Huh?  Sine waves are a mathematical curve describing smooth repetitive oscillations.  Like…tides, sonar pulses, sunrise/sunset observations, or the music booming out of your iPod.

I even use math to calculate how long I should run on the elliptical trainer down in the ship’s exercise space.  If I set the resistance to 8, and use a cross training setting, it takes around 35 minutes to ‘run’ the equivalent of one slice of cake!

Just in case you haven’t gotten the message—math is good.  Number sense is critical—even if you want to run off to sea!

Personal Log

IT’S A FIELD TRIP!!

I love a field trip.  There’s nothing like loading up in the bus and taking off in search of the great unknown.  While we were parked at the Cold Bay pier, we had a visit from the Cold Bay School.  The 8 students, plus their teacher and a classroom aide, came to check out the Rainier.  CO Rick Brennan gave them a tour, starting at the bridge, and ending with lunch in the wardroom.  Along the way, they learned about ships and ship life, NOAA, and the science of hydrography. Lunch was a real hit, since the kids all bring their own lunches to school.  Who wouldn’t like halibut tacos with all the fixings from the galley, or a peanut butter and jelly sandwich handmade by Commander Rick Brennan with a fresh cookie for dessert?

I tagged along on the tour to talk with some of the kids and their teacher and to compare notes about schools.  While I always think of my school as small, with only 150 students, the school in Cold Bay is really small.  There are 8 students and they represent grades 1 through 7.  While the school is small, each student uses an iPad to access a wide variety of educational resources. It’s even better when that technology-based learning is supplemented by some hands-on field trip-based learning.  This was their second field trip of the week; they had spent a day with a wildlife biologist helping install a motion-sensitive camera in the Izembek Wildlife Refuge (http://www.fws.gov/alaska/nwr/izembek/index.htm).

SAFETY FIRST

Where I live, in Colorado, we occasionally get snow days, when the roads are too dangerous to transport children to school.  Here at sea, we don’t worry too much about snow, but wind can create hazardous working conditions.  Yesterday we had what I would call a ‘Wind Day’; none of the survey launches went out.  The winds were gusting up to 50 knots, and were fairly steady at 30 knots.  That’s windy.  The surface of the bay was a froth of water, waves, and whitecaps.  Even the Black-legged Kittiwakes were having trouble flying!

Certainly not the sort of day where you want to send out teams of hydrographers in 28 foot long launches.  While safety is paramount, data quality also suffers in such ‘bouncy’ seas.  As the launch bounces from side to side or from front to back, the sonar sends its pings far afield.  It becomes difficult or impossible to drive straight, overlapping lines as you ‘mow the lawn’ through your polygon (Wait, there’s another math term!) , and turning the craft requires timing and skill as you move through the rolling seas.  As the Rainier nears the end of its time at sea and in Cold Bay, each day becomes critical to achieve its charting goals—but there’s plenty of work to do on board on a day like this.