Andrew Paley Blog Leg 4

Jason going over the side with the stab frame and new crawler unit for the deep profiler. The entire dive was around 9 hours in the end but was still very interesting to watch even if only for a small part. Credit: M. Elend, University of Washington, V21.
August 26-27: Arriving at Axial Seamount

The 26th was slow and easy-going given the nature of the dive involved. J2-1372 was a lengthy and involved process dealing with the Deep Profiler vehicle and cleaning the mooring cable, which all in all took around 7 hours to complete at the end of the day. The Deep Profiler Mooring is made of multiple parts, including a float at the top, the cable, the vehicle itself, and finally the mooring or anchor on the seafloor.

Personally, the vehicles are one of my favorite instruments on the cabled array as, with the help of a docking station, they physically anchor themselves to the cable and traverse up and down the water column with a pair of wheels, allowing them to seamlessly profile the deep ocean for a given distance while taking measurements of all kinds of fun ocean water properties. However, the dive itself isn’t all that exciting as while it is all an important part of keeping the array running, most of our time was spent cleaning the cable, which involves using a specialized brush attached to the ROV and moving up and down the length of the cable, (approximately 600 m), at what can only be described as a painfully slow rate of 10 m/min.

After the cable was scrubbed clean, the new crawler was then attached to the cable itself with the help of a specialized frame on the forward end of Jason before finally ascending to the surface.

From there, we began our transit to the Axial Eastern Caldera site. On the way I got to learn all about how to rig a CTD instrument for deployment in the undervator, as well as to get the instrument ready itself. CTDs, which stand for Conductivity, Temperature, and Depth, are specialized oceanographic instruments that can take continuous measurements on the properties of the water column at a given depth. The cabled units used by the Regional Cabled Array are like the ones in the rosette aboard the Thompson only rather than working in conjunction with Niskin bottles, these instruments take in continuous water samples that provide a constant stream of data.

With the help of my APL engineer friend, I got to assist in molly-coating the connectors to prevent ground faults, as well as making and attaching eel grips, which provide strain relief for the connectors/cables so that they aren’t damaged during deployment.

From there we repeated the process for another three units before using jute twine in the undervator with a combination of rachet straps and bungees to make sure that the units were secure, but that Jason could also easily break the line to easily deploy the unit when the time came.

However, that dive would happen while I was asleep and the next day would be completely occupied by working with the RCA team to get another instrument, the RAS PPS, rigged and ready for deployment.

Pre-deployment deck photo of fluid- and microbial-DNA samplers RASFLA/PPSDNA, inside a seafloor-frame, before deployment in the International District Hydrothermal Field, on dive J2-1190 during VISIONS’19. The fluid sampler is attached to a saddle on the left side of the frame.
Photo Credit: M. Elend; University of Washington; V19

The RAS PPS is a massive set of instruments and samplers that lives within its own frame. The RAS part acts as a fluid sampler, while the PPS is for sampling of microbial DAN.  But, you’d have no idea by just immediately looking at the instrument itself. The entire instrument is a massive conglomeration of tubes and chambers all carefully connected with piping and junctions that create what are essentially two water loops. From there, both loops come together and run a few meters to the vent cap where along the way all the power cables and tubing is held together, strain relieved, and carefully wrapped in a plastic housing that protects the delicate tubing.

From the vent cap,  temperature probes, which will eventually sit in hydrothermal flow and gather fluid samples and microbial samples, are piped back to the main unit over the course of a year.

One of the coolest parts I learned is that the unit itself is not continuous and can be triggered remotely using code from shore in Seattle, which is astonishing to think about given it’s a 1500 meters below the surface and nearly 300 miles offshore.

All in all, the entire thing is still a lot to wrap my head around, however we still have two days to get it ready so I’m looking forward to continuing to learn more about this incredible instrument tomorrow.

It was a relatively short mobilization period for this final Leg, but nevertheless its always fun to watch the massive basket be lifted onto the ship before we get ready to head off again into the open sea. Credit: M. Elend, University of Washington, V21.

August 25: Onward we go – Leg 4 Begins

Today marks the first true day of Leg 4 as, once more with a batch of new sailors, we sailed out of Newport Harbor, past the bar and into the open ocean where after a two-hour transit we would arrive at the Endurance Offshore Site. On the way there, we once again drilled how to put on emergency immersion suits, fire responses, and other basic introductory information to ship life before finally settling in as we continued our steam onwards. It was at this point that I found myself with some downtime and was able to practice more rigging skills such as various knots and splices. Of particular interest today was the constrictor knot, the double bowline, and finally the double eye splice. The constrictor is a lesser-known cousin of the clove hitch, which is commonly seen aboard any ships. With an “x” formed at the beginning as opposed to the end, it cinches down easily and holds even when not under tension making it a valuable tool. The double bowline is simply a bowline with an extra half hitch to anchor it and prevent it from coming undone even when wet, making it a vast improvement aboard ships. And finally, I got to try my hand at a double-eye splice, which ends up looking like a “y” with two eyes on the end. It’s a little more work than just two eye splices, but because it’s made from 4-strand line it is arguably stronger than the typical 3-strand eye and for rigging instruments it also reduces the number of lines you have running at a given time, so it definitely has its tradeoffs.

I didn’t spend all my time learning to tie knots though, I also got to be trained in a few new skills that I very much am looking forward to putting into practice during this final leg of the cruise.  Due to an increased number of students and volunteers to fulfill normal logging duties in the van, I’ve been given the opportunity to move to a standby watch and learn more about the documentation side of a typical VISIONs’ cruise. This includes taking photos of ROV launches and recoveries before uploading them and tagging them with the appropriate labels, as well as creating highlight movies of dive operations that include only the most important points of a given operation such as the vehicle interacting with an instrument, taking a sample, or other cool moments. These are all important to cutting down the time it takes to go back and review a given operation so that someone doesn’t have to sit through a 10-hour dive movie just to figure out what happened and serves as a valuable tool for outreach which is an aspect, I’m particularly excited about. All in all, I’m fairly new to photography and video-editing so I’m still taking steps to learn everything I need to and improve but ultimately, I’m excited for this opportunity to learn about a different aspect of daily operations.

Finally, towards the end of the day, I got to once again prepare a CTD rosette for a cast by cocking the niskin bottles and ensuring the seals and magnetic locks are ready to go. This has been a fairly busy day, but honestly in a weird way it’s the constant controlled chaos of daily operations that keeps me sane and I’m excited for what’s to come on this leg.