In October we ventured out to the Washington Coast for a short trip involving seafloor coring. We had some pretty rough days with the winds clocking over 50 knots. Typically we may get hammered with a large NW swell this time of year but mostly things were out of the SW. Not overly huge, but 20 feet and 10 seconds is no fun! That’s Stacked Tight! Here is what it looked like:
Rough weather from the bridge: (Notice the rusty water from the roll tank vents on the upper deck)
From the stern:
The coring took place along the Washington Coast along the continental shelf. Earlier mapping trips had identified some locations with methane gas seeps. This trip was to try to drop a core into those seeps and try to analyze the mud for microorganisms that thrive in the seeps.
Birds following us around. Do they think we are a fishing trawler with some scraps for them?:
The first step is the get a detailed map of the area with our ships multi-beam transducer. We just make several passes like mowing the lawn at around four knots while the marine techs tune the sonar beam to capture an image of the actual seep bubbles. When the weather really kicked up, this is the only part of the operation we could do. All over the side ops were cancelled.
Once the seep is identified, they drop a core over the side and try to hit the top of the seep. This is more of a luck type operation than skill. The core is basically a huge stack of weights on the end of a section (or multiple sections) of hardened drill casing. A clear plastic sleeve fits inside the drill casing and when the core is brought to the surface and secured on deck, the clear sleeve containing the mud slides out from the drill case and can be cut at different intervals and frozen in the ships science freezers. Once ashore the samples will keep some researchers busy for the next year or two in a lab somewhere.
The core and weight are nestled in the cradle near the guy in the blue hard hat:
The core has been removed from the cradle and lowered over the side:
The core being brought back onboard. Notice the mud on the casing. Then the sleeve is removed from the casing with the mud inside:
All of the lifting and lowering of the core are done with our huge trawl winches located down inside the ship. The winch wire is reeved up through the crane base and over a two meter block that attaches near the end of the boom of the crane. The crane is only used to swing the core over the side and then it is placed in a large crutch to help support the weight. The core is dropped with the winches until is plunges into the bottom. We can almost instantly tell if we hit the spot by how much tension is metered when we begin to pull the core off the bottom. If the tension remains fairly low then we know we hit a hard spot or rock and the core did not penetrate. If the tension really spikes then we know it was really driven into the sea floor.
This was a fairly hard operation to photograph, as I was running the winches most of the time. Here is the view from the winch control. We can see the trawl winches in the winch room on the monitors:
We returned to Seattle’s Pier 91 to unload our science guests. I snapped a panoramic photo with my cell phone. Pier 91 is where much of the Alaska Trawler Fleet calls home.