by Ian Murdoch
As an NMF Mechanical Technician (National Marine Facilities) It is my job on the Ellet Line Cruise to provide support to the scientists using different equipment such as CTDs, Milli-Q systems, lab containers, Liquid Nitrogen Generator, -20, -80 Scientific freezers, Laboratory Gas supplies and Deck winches. I am also involved in the deployment and recovery of epibenthic Sleds, Gliders and CTD’S.
So you may be wondering what epibenthic sleds are? You’re not the only one. I’ll leave the technical explanation to Peter Lamont (see yesterday’s post). However I will be assisting in deploying and recovering the equipment in one piece! For this we will be using the ships trawl warp, this is a 15,000 meter galvanized steel tapered wire. As you can imagine this is very expensive to replace. At sea we cannot see the seashells on the seafloor, so towing the sled into something that just wont budge is a possibility. This would rapidly increase the tension and damage our wire. That’s where weak links come in to protect it! Using these we can limit the amount of load seen on the wire before breaking point.
The traction winch is designed to control the tension of a steel wire, both when paying in and paying out. The unit is powered by frequency controlled motors where the speed and torque is controlled by the control system. The brake is of a fail-safe design, where hydraulic pressure controlled by an electrically operated valve is required to disengage the brake. When the brake control valve is de-energized, hydraulic supply to the brake is stopped and the brake engages. The brake acts as the primary means of static load holding. The winch drive acts as the primary mean of dynamic load holding.
While not on deck you can usually find me in the Galley gazing at all the tasty grub on offer or down the gym after one of Jackie’s delicious deserts trying to burn it off!
Photos by Ian Murdoch (and one of Ian that we sneaked in, by Karen Wilson)