CASSIS supported the scientific objectives of the BLUEcoast project over a three year period, undertaking survey campaigns in Cornwall, Essex and Morecambe Bay. The requirements of the BLUEcoast project and the areas being studied, meant that each deployment site was different in nature and the equipment required also varied.
At the beginning of the project, the Science Lead approached CASSIS with their requirements and together, a plan was formulated for each work area that utilised our knowledge of instrumentation systems and deployment platforms whilst meeting the scientific objectives.
Bespoke instrumentation deployment frames were fabricated; existing frames were utilised when possible and modified as required to reduce costs. Custom made brackets for the required instrumentation were designed and fabricated in-house.
BLUEcoast required the deployment of many instruments from simple temperature and pressure sensors to advance sonar units. All of the instruments are inspected, tested and prepared in advance of each deployment so there is confidence of them operating successfully in the field. Sampling protocols were discussed with the Science Lead and options presented regarding battery endurance versus sampling frequency/interval and data storage capacity. Those same instruments are inspected, checked and tested after each deployment to verify they worked correctly.
CASSIS personnel were heavily involved in the logistics surrounding survey campaigns; packing equipment, loading vehicles, driving the equipment to site, participating in the survey activities, preparing the equipment on site and participating in the deployments and recoveries of the instrumented frames, sometimes independently of scientific oversight.
The first campaign was in Perranporth, Cornwall. The requirements were to deploy Mini-STABLE frames off the coast. There were two deployments to capture data from the summer and also during the winter.
The focus for BLUEcoast then moved to the Blackwater Estuary in Essex. The Mini-STABLE frames were deployed in the estuary, in a different environment to that near Perranporth. Again, there were two sets of deployments to capture summer and winter data. Finally the focus for BLUEcoast moved to Morecambe Bay near Flookburgh. This is an intertidal mud flat so CASSIS personnel face different challenges to those previously encountered. These used a different type of frame and a host of different instruments to record data. Again, there were summer and winter deployments to manage.
The RAPID programme approached CASSIS to capitalise upon our expertise in lander design and communication techniques to solve an issue they were encountering with traditional methods of data recovery from deep ocean oceanographic instruments.
The solution was to employ MYRTLE-X to collect the data from nearby instrumented moorings and store the data inside releasable pods. The pods can be released at timed intervals or upon demand and the data is transmitted back to the UK via satellite communication systems.
The MYRTLE-X also has the capability to acoustically transfer data to a nearby vessel. This could be a surface vessel such as a research ship or wave glider, or a subsurface vessel such as a Slocum Glider, Sea Glider or an autonomous underwater vehicle, such as Autosub.
In a parallel exercise to MYRTLE-X, the RAPID programme team wanted CASSIS engineers to develop an acoustic data telemetry system using a Liquid Robotics Wave Glider as an autonomous surface vehicle capable of communicating with instrumented ocean moorings and with bottom located landers such as MYRTLE-X.
The instrumented test mooring was deployed in February 2018 off Gran Canaria. The ACSIS Wave Glider successfully downloaded data from the mooring and from MYRTLE-X which was deployed 0.5 mile away from the mooring site. A synopsis of the data from the mooring was transmitted back to base using Iridium data telemetry.
This application not only highlights the value of being able to safeguard sensor data from long-term moorings but also the ability to change sensor sampling parameters remotely during the deployment.
GNSS Wave Glider
The GNSS Wave Glider was developed by NOC and Newcastle University under a three year grant from NERC. It can measure sea level directly at the ocean surface using GPS/GNSS to a resolution of 1 cm and an accuracy of ±3 cm. The autonomous vehicle uses wave powered propulsion and solar power so can operate for over a year in the deep ocean.
The GNSS Wave Glider was trialled successfully on Loch Ness in March 2013. Its first open sea trials were in the North Sea in July/August 2016 when the vehicle was deployed for two weeks. Its course was plotted to coincide with the overhead passes of several altimeter satellites so that the simultaneously recorded data could be compared later.
During December 2017 to February 2018 the GNSS Wave Glider was deployed near to King George Island off the Antarctic Peninsula and piloted all the way to just outside Port Stanley Harbour in the Falkland Islands. A journey of over 1,000 km.
LOCATE called upon CASSIS engineers for help in collecting samples and developing a system to collect measurements from rivers and estuaries. River water samples were collected and processed in-situ, once-a-month for a year at two local rivers. This was complemented by quarterly sampling along estuaries in Northern England. CASSIS were responsible for arranging access to these locations and coordinating logistics to enable the sampling to proceed successfully.
The next phase of LOCATE was to design and install an instrumentation system into a freshwater and estuarine site on a specified river. The system was designed using sensors and components from different suppliers and brought together into a complete package. The design of the system involved various component parts of CASSIS, including mechanical engineering design and fabrication, electronics engineering design and construction, plus a working party from both groups to undertake the installations.
CASSIS engineers became involved in the Wirewall project to take a design that was used out at sea, in open water and to adapt it for use on the shoreline. Wirewall uses an array of wires arranged in a frame to measure horizontal water velocities from sea defence over-topping events. CASSIS designers adapted and improved upon the original design, including; improving the string tensioning mechanism and improving the water resistance robustness of the connections used in the system. CASSIS personnel were also heavily involved in supporting the survey and data acquisition campaigns, often at short notice due to the need for high spring tides combined with strong onshore winds.
The FerryBox project utilised ‘ships-of-opportunity’ to gather scientific data on a regular basis that would otherwise be too costly to undertake using traditional methods. Commercial ferries were fitted with scientific instrumentation and data collected as the ferry travelled along its usual route. CASSIS personnel were heavily involved working with ferries and ferry companies that operated in the Irish Sea, between Great Britain and Ireland.
Due to the high sediment concentration of the water being sampled, frequent maintenance visits were required to keep the sensors operating properly. These visits would have to coincide to when the ferry was in port and between crossings.