At about 11:00 PM yesterday the dredge snagged on a rock on the sea floor, we stopped the ship and eventually worked it free with a combination ship maneuvering and wire tension changes.  When we finally pulled it up, we could see the massive rock that it was caught on, and had eventually broken off.  The samples we dredged up had substantially less vesicles (gas bubbles) than the previous two dredges.  Our time was spent cataloging the samples from the previous dredges and cutting the new rocks into smaller pieces for sampling, and eventually distribution to different organizations.  We set all the new rocks out to dry and assigned them all sample numbers.  In addition to regular sample tags, this is the first cruise to use the new IGSN ID tags.  They are supposed to be used globally in all fields of science, each has a barcode on it so it can be read with a handheld laser scanner (like the ones at the supermarket check-out counter).  They are designed to keep track of every single sample taken (since their implementation). The information will be stored in a large database so an individual sample’s information can be looked up easily.

At about 3:00 AM we deployed the dredge again, this time east along an underwater ridge running towards the Ofu seamount.  The pinger worked this well time, and we were able to keep track of it all the way to the bottom and back.  Watching the cable tension, we were able to precisely when the dredge touched down, and every time it caught a big rock, or snagged on something.  On one occasion, the tension jumped all the way up to 12,600 pounds (5,000-7,000lbs normally). We assume that that big jump corresponded to the massive 150 pound rock that we found in the dredge when it was brought up. 

We would have never collected the big rocks we are getting with the new dredge we made. The dredge we are using has been used for over 50 dredges, and what used to be an open-bottomed box (made out of 1.5 inch thick steel) is now more of a hexagon shape.  I guess the good dredges have to be broken in.  Gabe, the marine tech that is in charge of dredging operations, had no intention of replacing the current dredge with one of the three brand-new ones that are secured to the deck.  Maybe dredge designers should consider copying our dredge and manufacturing them to look the same.     

We started reeling in the 4,500 meters of dredge wire (at 50 meters a minute), and had plenty of to finish cataloging the previous samples, and even to go up to the bow and to watch the sunrise.  It was incredibly beautiful, there is nothing but super clear water in all directions, and the way the rising sun reflects off the swells has to be seen to be believed. 

The rocks we picked up in dredge number 4 had an extremely high olivine percentage (Picrite) and which greatly excited Matt Jackson because he could measure the helium isotope ratios present, and gather more data for his thesis project.  There was only one more dredge deployed the rest of the day, mainly due to the long transit time between the new dredge sites.  The crew used this time to set up a pool on the back deck and relax while watching the some amazingly green islands slip by.   

Blake English onboard the R/V Kilo Moana.