Recovering the Elwha tripod (and some surprises from the seafloor) (Mar 2013)

On March 8th we sailed to the Elwha delta aboard the R/V Centennial from Friday Harbor. Mission: recover the primary tripod which has been deployed since October 12th (5 months!). The weather was fabulous – calm seas, light breeze, and sunshine. We had some…challenges…recovering the tripod, but ultimately prevailed. We even took a few grab samples of the seabed using FHL’s Van Veen sampler. ┬áThe surface plume from the river was directed well to the east thanks to the new sandbar at the river mouth, but we did intersect it at one of the grab sample sites. What a view!

R/V Centennial with snowy Olympic Mountains in the background. The Centennial is a recommissioned fishing vessel and works well for tripod recoveries.

We recovered the tripod using the secondary acoustic release. The line for the primary release was a bit tangled. Above, Dan works to unlink the shackle from the retrieval line.

Sometimes the tripods pick up hitchhikers. A few minutes after the tripod arrived on deck, we spotted this little guy making a break for it. After a quick photo, we helped him on his way.

We took a few grab samples at the 10 m contour. Two were composed of medium sand, but one was still quite coarse.

The river turbidity was rather low on Friday, but there was still a lovely surface plume. In the distance, you can see waves breaking on the new sandbar.

Andrea, Dan, and Scott (from FHL) made quick work of removing the instruments from the tripod and deconstructing the frame. The instruments and frame came back to our shop at UW in Seattle for maintenance. We expect to redeploy this system in April – meanwhile, the secondary tripod will continue collecting data.