Blog 1 – The story of cable

Wow! My first day at sea has been amazing. There is so much to learn and so many scientists to speak to, the weather is perfect, and the food is excellent. But there is quite a bit of tension on the ship! Without this tension not much research would get done here on the R/V Melville where a science party of 37 individuals and 23 crew members coordinate and collaborate to find out some of the most pressing questions about the effects of climate change in aquatic ecosystems.

This tension that I am referring to is mostly found in the cables that support many of the specialized equipment that will be immersed deep in the sea. Think of the rope when you play tug-of-war. You have one half of your team on each side and you try to pull as hard as you can. The tension or force on the rope that builds up as each side is pulled can be measured in pounds or weight. If there is too much tension the rope could break.

Throughout this expedition, there will be numerous types of equipment immersed in the sea. The strength of cables used will guarantee that none of this equipment is lost at sea. The strength of the cables depends on the materials that they are made of such as steel as well as the weaving patterns that resemble the tug-of war ropes.

One strong cable is the CTD (conductivity, temperature, depth) wire. It is made of galvanized steel with a wrecking strength of 10,000 pounds! This means that an instrument weighing up to 5,000 pounds can be attached to this cable, lowered vertically into the sea, bounced around underwater increasing tension, and still not break. It is considered an electrical and mechanical cable meaning that signals will travel to the instrument and return to the ship carrying important data.



Robert Palomares, senior electronics technician, works on a termination using CTD wire.


Wire with fairings













Another type of cable used here is cable covered in fairings. These fairings reminded me of dragon-like spine scales that run infinitely into to the depths of the sea. The fairing design changes the flow of water making the towing of heavy equipment more stable at high speeds.



Dr. Mark Ohman, chief principal investigator of CCE LTER at Scripps Institution of Oceanography, UC San Diego


9/16 trawl cable













A very flexible, strong and light weight cable used here is the Vectran cable. It is synthetic and very versatile with electrical capabilities.

Yet, the strongest of them all, made of steel, is referred to as the 9/16 trawl cable because of its thickness. It is used for pulling some of the strongest loads.

Eventually, after many months and even years cables may lose their original tension due to rust, overuse, or getting caught under other structures. At this time, cables are removed to be recycled.