Empty cores from the multicore.

Empty cores from the multicore sampler. Click image for larger view and image credit.


Broken Multicore x Four

March 12, 2010

Benjamin Maurer
Scripps Institution of Oceanography

It has been days since we've recovered the multicore with any workable samples in it, and the scientists are growing restless. They gather repeatedly at the fantail, dressed in their foulies and ready for mud, only watch the empty cores come aboard again. With each successive failed coring attempt, the number of faithful researchers dwindles.

And then the multicore came back up busted. The trigger mechanism was frozen shut, and the multicore couldn’t be re-cocked. The "res techs," Jim and Brian, another grad student, Kate, and I disassembled the multicore spider and took it down to the machine shop. There, with the help of Sabrina, an engineer, and a bit of ingenuity, we managed to smash the trigger pins straight enough to pull them out. But the instrument still wasn’t functional. Sabrina and I quickly fabbed up a new trigger system out of a couple nuts and bolts, some scrap plates, and pair of pins. Thanks, Sabrina!

One of the irreparably damaged triggers.

One of the irreparably damaged triggers. Click image for larger view and image credit.


Jim and Brian, our amazing res-techs; there is no problem they can�t solve.

Jim and Brian, our amazing res-techs; it seems there is no problem they can’t solve. Click image for larger view and image credit.


At 5 a.m., we took our new trigger system back on deck and reassembled the multicore spider, only to realize that the delicate electrical conditions (from the multicore to the lab monitors) had been damaged in all the moving. So it was back to re-terminating that cable. I finished splicing, gluing, taping, gluing, taping, etc, at around 8:30, and by 9:30 we had the multicore headed back down to the deep.

At 11:00 a.m., the multicore came back up — empty.  Jim was immediately on it. There’s a viscously damped piston at the middle of the multicore that’s essential to its operation, and Jim had it apart by the time I made it onto the fantail. I helped him pull all the moving parts out of the center of the 816 kilogram (1,800 pound) multicore. Eight seized bolts, two ravaged rubber seals, and a complete set of new piston internals later, we were putting it all back together.  We tested the system once we’d wrestled it back together, and the new piston and trigger system worked great on deck.

Sabrina, engineer and trigger fabricator extraordinaire.

Sabrina is an engineer and trigger fabricator extraordinaire. Click image for larger view and image credit.


Success!  Bringing mud aboard in the multicore.

Success! Bringing mud aboard in the multicore. Click image for larger view and image credit.


At 8 p.m., as we are getting ready to put the multicore overboard, I tested the electrical connection. Grrrrr. The electrical connection had been destroyed as we pulled it through the block and then passed it back through on the reinstall. Back to splicing, gluing, taping, gluing, taping . . .

At 9:30, after more than 30 hours of work, we were "all systems go," deploying off the fantail. Breath held, I helped recover the multicore just before midnight. Mud! Woo hoo!

A huge thanks from all the muddy science team goes out to Jim, Brian, and Sabrina, whose hard work and ingenuity got the multicore operational once again.