My lab does moorings. Engineers design and build huge floats that sit on the surface, or just beneath it. The wire that holds these floats in place will extend to the heavy anchor on the ocean floor, with a set of instruments often spanning the entire depth. We deploy these at sea, and recover them months/years later. The return is a time series of selected oceanographic quantities, for the entire water column, in one location.
|Prepping the floats|
A couple of weeks back, we deployed and recovered a series of moorings for our CORC Project (more at http://mooring.ucsd.edu). In 90 hours, we deployed a glider, two bottom and two subsurface moorings, recovered one subsurface and two bottom-mounted instrument, and had zero relaxing transit. I'll describe the deployments here, and touch on the recovery process in a future post.
Surface and subsurface moorings have different designs, but similar deployment processes. The trick is to get the entire 1-4 km of cable, instruments, chain, floats, and anchor off of moving/bouncing boat without getting anything tangled.
To start, we angle the boat so it is roughly steaming towards the desired location. The large float is the first thing in the water. For surface moorings, this is a huge surface buoy, while subsurface floats are smaller. Instruments start on the main float itself, and continue along the cable in carefully determined intervals.
At the end of the wire, a couple lengths of chain, more flotation, and finally the anchor (normally railroad wheels) are lifted over the ship's edge. We continue to steam to the desired location, with sometimes trailing 4km of wire, floats, and instruments. Once the Chief Scientist gives the signal, the anchor is dropped and pulls all to rest vertically in the water column.
Anyways, watch a couple timelapses and check out a bunch of photos.
This is the beginning of the first deployment. It lasted over 6 hours, was in ~3800 meters of water, and had a subsurface float that rested at about 50 meters below the surface.
This is the end of the first deployment, the anchor is about to drop when the camera card fills.
This is the (almost) entirety of the Second Deployment. It lasted only about 2.5 hours, was in 800 meters of water, and again the SD Card filled up right before the anchor drop.
--Our instruments use magnets to induce tiny electric pulses in the wire that holds them in place. Similar to Morse Code, this process transmits all the data from each instrument to a single modem. The surface modem will transfer the data via satellite; the subsurface modem is acoustic, and will transmit the data to a passing glider, which will bring the data to the surface within reach of the satellite.
--Our deck leader is a salty German who has the uncanny ability to tell you exactly which box (of over 20) holds each wrench, bolt, and wire length. Rumor has it his toes are made of steel, and has no need for steel toed boots.
--Our lab is playing a large role in the OOI Project, where 4 moorings systems will be put in 4 of the roughest waters, essentially on the corners North and South America. The deployments and recoveries will be nothing short of exciting.
|Port Hueneme, in Oxnard|
|A ship, bigger than ours|
|Fully loaded, ready to depart|
|Some first years earned their sea legs|
|Paul caught a fish; lab BBQ a week later|
|Pre-Deployment meeting; Chief Scientist in sneakers, Deck Leader in Shorts and Boots|
|First Instrument; it's covered in Copper to keep off Bio-Fouling|
|Location of GoPro Camera|
|Last set of floats with release.|
|Deployment 2, surface floats.|
|Deck Leader, rolling a Cig|
|Our Bottom Releases are acoustic and let go only to a particular set of frequencies.|
|Anchor!! For Deployment 2|
|Unloading back at Port|