I am working as a Design Engineer on a project at Oregon State University to design, build, and operate a remotely-operated boat (R.O.B.) to be launched from a research vessel in Greenland. This enterprise is one part of a larger observational study to understand the physical coastal processes that are impacting the Rink Isbrae and Kangerdluggssup Sermerssua Glaciers. We are also collaborating with a mechanical engineering graduate student who is working on the analysis and prototyping of the physical set-up of the A-frame and winch as a school project. I am incorporating her work into Rob’s control system and coordinating with the scientists to make sure that I design Rob to the specifications needed to target our research questions.
R/V Rob’s goal is to drive up alongside glaciers in Western Greenland and then deploy instruments that take measurements of ocean current and temperature. This NASA-funded project will try to ascertain why two glaciers, in adjacent fiords, are changing in different ways. One is retreating, while the other is not. A hypothesis is that the ocean is warming one glacier’s terminus, but it is keeping the other glacier cool. To test this hypothesis, it is necessary to understand currents and temperatures of the ocean in the fiords.
Taking these measurements in close proximity is challenging since both of these glaciers are actively calving icebergs. It is too dangerous to take a human-controlled vessel into this area, hence the need for a remotely-operated one that can take the needed measurements.
The off-the-shelf Q-Boat 1800P an electric, remotely-operated boat produced by Oceanccience was chosen as a starting point to build upon. This boat, about two meters long, is powered by pair of one-horsepower electric motors and was designed to survey rivers and ponds. While it does not have the ideal hull shape for ocean operations, it does provide a tested design and propulsion system to start with.
Acoustic Doppler Current Profiler (ADCP)
The ADCP is, in effect, a sophisticated depth sounder/fish finder that not only looks for the first loud acoustic return (assumed to be the bottom), but also other returns. It then compares the returns’ frequency to what was transmitted in order to determine the Doppler shift due to the motion of the water. Combining such information, this instrument (RDI 300MHz Workhorse Monitor) can record the movement of up to the first 100m of water under the boat every second.
Conductivity, Temperature, Depth (CTD)
The CTD instrument measures conductivity (salinity), temperature, and its depth. From this information it is also possible to determine the density of the water. Because of the boat’s size, a small CTD was chosen that has a depth rating of 100m. However, to deploy this instrument, a winch and crane (known as an A-Frame) had to be added to the boat.
A small powered fishing reel winch was chosen due to R/V Rob’s small size. Multiple modifications were needed to make the winch remotely/autonomously controllable.