GoM Hydrate, Daily Log

Steven Constable

On this web page I will be posting daily updates on the progress of our cruise on the R.V. Point Sur in the Gulf of Mexico. The object of this project is to map seafloor gas hydrate at three or four locations in the GoM. Read from the bottom up.

Diary

We got into port around 1 pm yesterday, and took advantage of a break in the rain to get most of our stuff off the ship, followed by a few beers at "Cecil's". Cecil's is a grocery store with a fish cleaning station out back (where you can relax and drink your beer). Met a couple of locals with their tuna catch. The were, I think, most amused to meet a bunch of academics from California. We said we'd been on a ship and they asked what we had been fishing for.

Most of the morning has been spent waiting for a crane to lift off our winches and the truck which will take the gear back to San Diego. It has been dry all morning, but now it is raining - several of us were on deck when a squall announced its arrival with a flash of cloud to cloud lighting so close that one could imagine reaching out and touching it. Now we have a fuel tanker, crane, truck, and forklift all vying for space on the dock. But, we should have everything packed away in time to make the drive north to the airport.

All done. Signing off. See you next time. Steve.

Homeward bound! It is a little known fact that all ships have a secret, extra engine that the scientists are not allowed to use for their own work, but which is brought on line for the trip back to port. We will be getting in several hours earlier than we expected, but this just means that we can get a head start on demobbing the ship.

This cruise has gone remarkably well. The issues that we had were extremely minor, and we accomplished everything we came to do. SUESI didn't miss a beat, and all the Vulcans collected data on every deployment. Of course, we put a lot of effort into planning the trip and preparing the gear, and my engineers, techs, and students are all wonderfully talented people. The ship and its crew have provided excellent support for the project. But you can't count on the weather, and bad luck is always lurking out there waiting to get you. Fortunately, it didn't find us this trip. Some say...

This is our last day of towing. We have made up some time and so Peter ran the last line back over Green Knoll to get a little more data on this geological feature. We have no idea what we might see, but then nobody has ever towed a Vulcan array over a near-surface salt dome before, so who knows? Hypothesis driven science is all well and good, but I am a firm believer in just going to have a look. I have a number of good papers that have resulted from this approach to life.

At 10 am we started hauling SUESI in on the winch and recovered the array. The seas are still glassy (even more so) and I got some good photos of Vulcan 2 coming aboard. I then had the tedious task of navigating and recovering the acoustic transponder array. One of the biggest issues with this type of work is knowing where SUESI and the Vulcan array is. There are various approaches, which I won't go into here, but for this cruise what we did was to moor 4 acoustic transponders 10 m off the seafloor in the middle of each survey area. SUESI has an acoustic ranging system which measures distances to each of these transponders, to within a meter or better. Combined with depth, which is accurately measured using a pressure gauge, we can triangulate SUESI's position. A relay transponder on the tail end of the array gets us that position too. All this relies on knowing where the moored transponders are, which we determine by acoustically ranging to them from the ship (which has GPS positions, of course). This, and releasing them from the seafloor to recover them, kept me busy until midnight.

Towing Green Canyon 955. Boring is good. So is the food. And the weather.

The midnight shift towed SUESI across the deeper seafloor towards the next prospect, Green Canyon 955, with a diversion to go over Green Knoll, a salt body that comes close to the seafloor. By the time I got up this morning we had started GC 955. We really have done well with the weather, and today was approaching glassy seas. The captain had been promising me that these conditions would come, and I was looking forward to giving him grief for not delivering, but I guess I'm out of luck. Oh well, glassy seas are nice, although we're having trouble with the heat exchangers for the air conditioning, which seem to rely on water motion across the hull. The bridge, and my cabin, are freezing of course, but the lab is getting cosy warm. Fortunately SUESI's power supply is ticking over at 13 kW, but rated to 30 kW, so it isn't in too much danger of getting hot.

On the blog for the Uruguay cruise I commented that green flash skeptics need to spend some time at sea, but I didn't get a good photograph to back up my assertion. This has been corrected. Also, we had a nice moonrise minutes later. See photos.

We towed Green Canyon 783 all day, which was pretty boring apart from lunch and dinner. What passed for excitement came at the end of my shift when we towed SUESI down off the prospect onto the flat seafloor in deeper water just before midnight. We passed things off to the next shift and that was the day.

I got up at breakfast to find a fresh pot of Peets coffee brewed and the first three Vulcans in. I lent a hand and we soon had the entire array in the water. We are going to tow Green Canyon 781, and then instead of recovering the gear and redeploying it at Green Canyon 955, we are going to collect data between the two prospects, towing over Green Knoll, a shallow salt body. This will take about the same time as turning the array around, so instead of toiling in the hot sun, we'll collect data working from an air-conditioned winch station instead.

I should take time out to say that the Point Sur has been a great vessel for our work. The 0.680" winch, which is critical for deep-towing SUESI, has functioned well, and the winch station is the nicest we've used. It is situated in the aft control station of the bridge, with 270 degree views, and has a computer-controlled option for paying out and hauling in at constant rates (no more bungie cords on the winch control lever!). The food has been great - Alex to cook is highly innovative, and we've eaten things I've never eaten before. Finally, the internet is way faster than anything I've had on a ship. Web browsing actually works, and uploading photos for the web page is a breeze.

We successfully avoided the brine pool, and recovered SUESI and the Vulcans around lunch time. The midnight crew went to bed and my shift worked on data download, battery charging, transponder navigation and recovery, and Vulcan startup. We had a bit of a break because of a 5-hour transit to Green Canyon, so I went to bed early in order to get up at breakfast and help the midnight crew deploy the gear.

We are well into our second deployment in the Orca Basin, and things are still going well.

On the north side of the prospect is a basin with a pool of brine on the seafloor, which sounded like an interesting thing to collect data in, until I calculated what the effect on SUESI would be. The output current of SUESI is limited by the resistance of the antenna, which for this project we have made as small as possible, and the resistance of the electrodes to seawater. The whole system is designed around the conductivity of normal seawater. But if we drove SUESI into the brine pool, she would try to output 2,200 amps (she is rated to 500), trying to draw about 70 kW from our 30 kW topside power supply. At best our power supply would trip on over-current, and more likely something would break in SUESI before that happened. So, we have decided to avoid the brine pool.

I woke this morning around 8 am and divined from the engine noise that we had just finished deploying the last transponder and were transiting to the next prospect. I got up and ambled on deck and indeed everything was ready for deployment, and I realized that we were going to finally find out what working in the heat of the day was going to be like. I helped the midnight shift start deploying the Vulcan array until more of the noon shift surfaced, and then spent some time taking photographs. One photo, which I posted, shows a ship crossing our stern only twice the distance of the far Vulcan, which remains on the surface 1600 m behind the ship until we deploy SUESI and drag it down to the depths. Such things worry me - there is a fair amount of ship traffic out here, and having a freighter drive through the Vulcan array is sure to spoil our whole day.

SUESI continued to behave well through the end of the first prospect (Walker Ridge 313 for those who know the Gulf of Mexico block numbers). We started hauling in at dinner time and during the early evening we landed SUESI on deck and recovered the Vulcan array. Again, we were grateful that we were working at night. The recovery went smoothly, and afterward we navigated the transponder locations and started releasing them. This is only the second time we have used a moored acoustic transponder array to navigate SUESI's position and it worked well. Then over to the second prospect (Orca Basin, Walker Ridge 100) to deploy the transponders. By now it was well past midnight and I left all this to the midnight shift.

The marine EM laboratory has a shirt with our seafloor instrument logo and the motto "Boring is good". Today was good. We are driving the ship up and down lines across the first prospect, Walker Ridge 313, and there is no excitement. Two people on the winch, two people hanging out, everyone up for lunch during the shift change. Weather good, food good, equipment working. Life is good.

Arrived on station as expected just after 3 in the morning. Technically, the noon shift should have been in their bunks, but of course everyone wanted to be part of the action, and you really need more than 4 people when all the gear is going over. Since nearly everything was ready to go and we were just transiting, the noon shift went to bed a few hours early and set alarms for 3 am. I got up just as the midnight shift was getting ready to deploy the four acoustic transponder instruments that we were going to use to navigate the deep-towed EM transmitter (SUESI). By 6 am the transponders were over and we were ready to start deploying our array of Vulcan EM receivers and SUESI. We had been a little upset that we had to start operations in the middle of the night, but when the sun came up we realized that this was, in fact, a good thing. By 9 am we were deck testing SUESI and were very happy to find that everything was working (it really is very disappointing if it is not working - at that point you might have to spend 3 hours bringing everything back in, for 6 hours of hard work wasted). We put her into the water and starting lowering the whole kit to the seafloor, 2000 m below. The array is 1630 m long with 6 Vulcan instruments. In the past we have only used about 1200 m arrays with 4 instruments, so this is a significant increase in array size and a new thing for us. By 11:30 SUESI was at her flying height of 100 m above the seafloor, putting out 260 amps of current, and everything working as it should. We are collecting data at last.

Fire and boat drill at 07:00 (see photo), and then push off at 08:00. Technically, we could have pushed off at midnight, but it is a bit of a gamble to set sail while the lab was unsecured, and we had all been working hard all afternoon to get things on board and wired up. We have an 18-hour transit to the first survey area, arriving at 03:00 tomorrow, so after lunch the midnight shift went to bed and the noon shift worked on preparing equipment for deployment, making acoustics work, etc. etc. Things go slow the first day - the seas were just bumpy enough that even the hardy souls could feel a little groggy. Some of us decided to test our mettle by not taking any meclazine, which some of us got away with.

Rain. Off at 8:30 to drive down to Cocodrie, where LUMCON has its port facility and where we join our ship, the R/V Point Sur. Drive south of New Orleans and stop about 200 m short of where the road ends in the mixed marsh and seawater that serves as a coast, and you will find LUMCON. Mercifully, the weather was not too hot (low 80's) and the mosquitos not too bad. Our truck full of gear was there waiting for us, and we started to load around lunchtime. Things went pretty quickly, but we had a lot of stuff and it was close to dinner by the time everything was on board. We split into shifts, and 4 of us tied down the deck until midnight and then the other shift of 4 tied down the lab.

Travel day. Our colleagues from Ocean Floor Geophysics in Canada met us in Dallas-Fort Worth (DFW, American Airlines' hub - I sorta wish I had kept track of how many times I had passed through here, must be hundreds). We went on to New Orleans, where we overnighted, in time for dinner. This of course, was planned, since the dining is good in this city. The restaurant that Jake scoped out was busy, so we hit the streets in the French Quarter and wandered around until we ended up at NOLA, which used to be my favorite restaurant when I was passing through New Orleans in the late 1990's during the early development of marine MT. One of Emeril Lagasse's places, although I didn't notice that when I first went there. We luckily found a table so, per diem be damned, we had a great meal. The youngsters went off to find some special cocktail that Peter had decided could only be had in New Orleans, while Big Peter and I went back to the hotel to prepare for an early start.

Nothing to report yet. After months of instrument preparation and planning, we are all flying to New Orleans tomorrow to start our latest adventure. Stay tuned...