Behind the scenes of the ship

This week we have been exploring all the parts of the ship we have not yet discovered and were lucky enough to get shown around the engine room and the bridge. It is evident that each area of a ship (bridge, engines, science etc.) has a group of people doing those specific jobs and that the combination of everyone doing their part keeps everything running smoothly; like cogs in a massive machine. 

The engine room control panel. With that many buttons no wonder it takes so much training to work in the engine room!

The engine room is located in the hull of the ship and is the biggest room on board by far, taking up about 2/3rds of the bottom deck. This is obviously a very important part of the ship because without it we would not be moving anywhere! The Langseth has 2 engines leading to 2 propellers and also 1 bow-thruster. There are so many different bits of machinery down there that it can take 4 years of studying to be qualified to work in the engine room. It is very loud and warm but surprisingly clean and tidy. There are also 2 compressors which are used to pressurise the air for the air guns that we tow. 

One of the very noisy compressors. It is hard to portray the size of these in a photo, they are huge!

The heat from the engines is used to produce all the hot water for the ship and the engine room also has machines for desalinising our water. Fuel usage is constantly monitored and fuel moved between all the many tanks spread around the ship to ensure even weight distribution. Even though we only travel at about 4 knots whilst acquiring data we burn between 5000-6000 Gallons of fuel a day due to the massive load of the equipment we are towing behind us.

One of the two engines

The bridge sits at the front of the ship on top of the main living quarters. From here it seems as if practically everything can be controlled. They drive the ship when we are not driving from the main science lab during acquisition, control the speed, can manage the safety aspects including all alarms and watertight doors and keep a look out for anything floating past that might get caught up in our seismic gear (so far buoys and pallets have been sighted). One very important job of the bridge is to communicate with other nearby vessels. Nobody would expect us to be towing 6km of streamers so we have to make sure we let other ships know with enough time to arrange safe passing, therefore avoiding collisions.

This is the main control panel in the bridge. There are screens for  navigation and
radar as well as all the speed controls. There are two smaller control panels
on the port and starboard sides of the bridge for work that
involves careful maneuvering e.g. picking up OBS's. 

The last seismic line is just being finished right now and then we can get ready to begin equipment recovery. It is about 40 hours until we are back on dry land again! 

Tessa Gregory

University of Southampton  

Binning is the name of the game

As we come to the end of our cruise I thought that now would be a good time to talk about the way in which both seismic and multi-beam sonar data are quantified (basically nerd out). In both cases we "bin" the data into grid cells, which are predefined based on the resolution that we expect to achieve given the ideal data density of individual cells within the grid. 

A screen capture from the multi-beam sonar Seafloor Information System (SIS).
The image on the left shows swath coverage. The image on the right shows an active ping through the water column.

Multi-beam sonar (swath seafloor mapping) data are collected, gridded (binned) to the predefined cell size, and output in two flavors. Bathymetric grids, which are essentially 3D topographic maps, and Backscatter grids, which display the reflectivity of the seafloor. The reflectivity varies due to both incidence angle of the respective beams and the density of the surface (e.g. hard rock, sediment etc). As the ship moves along at a given velocity, the multi-beam sonar sends a "ping" from the transducers (transmitters) to the seafloor and then waits until the receipt of the last return to ping again. The ping rate (Hz or 1/seconds) is a function of the depth of the ocean as well as the sound speed through water (XBT's are useful!). The swath width also scales as a function of depth. Our average depth is ~4800m (2.98 miles), which allows for an achievable swath width of ~20km (12.43 miles!).

Swath coverage display of the backscatter (reflectivity of the seafloor) collected across a swath.

In order to gain insight on the density of the multi-channel seismic (MCS) data that we are collecting we use the Spectra software package. Spectra tracks the position of the ship, streamers, and air guns in real time using GPS and an acoustic network, and then bins the data accordingly within the predefined grid. The goal is to get an equal amount of seismic traces (reflected seismic waves) in each bin. The traces can then be stacked (combined), which increases the signal to noise ratio. Stacked traces within a bin are called "fold" and ideally represent traces from all offsets along the streamer in respect to the source.

A screen capture of the Spectra display. The image on the left shows active binning of the MCS data.
The image on the right shows the bins being infilled (filling holes).

We are getting to the end of the "No Mores," which means we are finished on Friday!! Stay tuned for a word from our Chief Scientist along with a look at the MCS data (and our cruise pic). 

James Gibson

Lamont-Doherty

Nom, Nom, Nom: Meals aboard the R/V Langseth

After all these posts about how we live and work onboard the R/V Langseth you may just be wondering what sort of sustenance keeps us going during the long hours.  Well you’re in luck! The excellent cooks serve meals with a smile promptly three times a day at 7:20 am, 11:30 am, and 5:30 pm.  Breakfasts always include mountains of eggs, bacon, sausages, and pancakes and on special occasions scrumptious muffins.  Lunch usually comes with toasty grilled sandwiches, soup that warms your limbs, and crunchy French fries.  Dinner varies but commonly consists of a juicy steak or pork chop, rice, mashed potatoes that put even your Mom’s Thanksgiving potatoes to shame, and a delicious desert like cherry pie.  The salad bar is open 24 hours a day and even this far into the cruise still contains crisp spinach, olives, tomatoes, and a variety of other vegetables.

A sampling of the meals served onboard with cooked by the always smiling galley staff.
From left to right breakfast, lunch, and dinner.
In the center image the galley staff made up of June, Hervin, and Brian pose behind a lunch of pizza and soda.

We are now in the home stretch of our cruise, steaming furiously down our final sail lines to complete our 3D grid.  Can’t believe there’s only four more dinners until we set foot back on dry land!

Natalie Accardo

Lamont-Doherty

5 lessons I have learnt on my first scientific cruise

I was sent to join this cruise half way through because a lot of the scientific party had to leave and nobody more qualified than me could be found at such short notice! I have never been on a cruise before and had no idea what to expect, or any idea how complex and time consuming 3D seismic acquisition is. I have learnt so much about the technical side of acquisition and a little bit about the processing side; however I have also gained a lot of non-scientific tips and tricks!

Here are my top 5 tips: 

1) ‘Boring science is good science’ – If you are bored on a 6 hour watch that is a good thing because it means that everything is running smoothly and good data is being collected. Having things to do is always a bad sign! Things have been running pretty well recently and as a result I have greatly improved my crossword skills.

2) Things will break, don’t panic! – This is a hand me down ship filled with second-hand instruments from industry vessels. Because of this a lot of the equipment is temperamental and repeatedly needs to be fixed. However, I have also seen instruments that have been offline for days randomly start working again so you never know!

3) Duck tape has a million uses – There is no end to the list of things duck tape is used for on this ship: keeping weights in place on streamers, keeping your laptop on the desk during bad weather, taping your ladder to your bunk so it doesn’t bang during rough weather and keeping ropes in place on the deck to name a few. It seems like any problem can be fixed with tape.

If you don't want your office chair rolling around or you need a cable tie just use tape!

4) Hoard food – When food you like is put out in the mess then take it while you can. A few days ago a gigantic tub of mini snickers and bounty bars was put out in the mess….I have never seen chocolate disappear so fast!

5) Taking a shower is the most dangerous activity on the ship – I recommend keeping either an elbow or hand on the wall at all times so you can feel when you start to move. I think taking a shower is probably the best form of exercise on the ship because of the amount of effort and energy it takes just to balance. Also, never soap the bottom of your feet in rough seas. That is probably classified as an extreme sport!

Tessa Gregory

University of Southampton

Free Time: Let's see what we have here!

As Natalie told you, the Main Lab operates for 24 hours a day, but we have a 6 hour shift (nobody can work for 24 hours of course!).  So, what are we going to do in our free time? That is a great question!  Let me show you the Marcus Langseth's free-time facilities.

Located next to the Galley we have our Library which has a lot of good books (I was reading the Che Guevara's travel book before the beginning of this part II, I really want to finish it!) and these excellent chairs...they're really comfortable, believe me. You can also find a variety of mystery, fiction and scientific books on the shelves.

The library with a wide variety of books

Yeah, but John actually I'm not a book lover ...

No problem! This is what you need! A 42-inch TV screen and a big collection of movies and TV shows. Ah, and don't forget the PS3, which makes the crew's free-time fun.  I have to admit something to you, I've never used the movie room, but maybe sometime I will go there to catch a movie or documentary.

The movie room with seating for plenty

But if you're an athletic person, this is your place, the gym!
It's a little bit small, but if you think we're in the middle of the ocean, the luxury of having some equipment must be appreciated.

The gym ... be careful when the ship is moving!

So, there is a treadmill, some free weights, etc. Be aware of the pitch, roll and heave! These are the movements made by the ship.  Instead of explaining them, I'll post an image which can perfectly illustrate what I'm trying to say.

The differences between pitching, rolling, and heaving

For those who appreciate an indoor sport, we also have a ping-pong table. It's located one level below the Galley, at the Main Deck. I didn't use this table either, but I'll launch a challenge: Try to play ping-pong during rough seas! Imagine how cool a ping-pong game is inside a ship facing waves of 5 or 7m (or even higher).

The ping pong table ... this could get interesting in rough seas

Thank you...or should I say Obrigado?

João (John) Pedro T. Zielinski
Complutense University of Madrid/Federal University of Santa Catarina