Oceanography | Vol. 38, No. 3
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agreement. The non-commercial unit sampled at a faster rate. In
general, most of the drifters followed similar patterns. The drifter
built by the instructors had a drogue depth of 15 m, which may
explain its different trajectory at the start of the release. The drifter
from Team 3 had a larger surface area protruding out of the water,
which may explain why it deviated from the other trajectories,
potentially being more strongly carried by wind.
Figure 7b,c shows the location of the drifter from Team 1 with
the non-commercial GPS at three timestamps. Figure 7b shows
the position over a contour plot of the bathymetry with an orange
arrow denoting the wind speed and direction and the tide height
listed in the panel header. In Figure 7c, the position is shown over
the flow field obtained from the +Atlantic CoLAB MOHID model.
While the temporal resolution of the model is low (one snapshot
every three hours), it is still a helpful tool for estimating the trajec-
tory of the drifter and teaching students about data assimilation.
POSSIBLE MODIFICATIONS
COURSE MODIFICATIONS
Most student designs were variations of the example drifter intro-
duced during the course. To encourage greater diversity in design,
we recommend presenting multiple example drifters. Additionally,
we suggest documenting and evaluating how design differences
affect water-following performance. Increasing testing opportuni-
ties at the deployment site would also be beneficial; for instance,
teams could deploy multiple drifters over several days to better
track current patterns. To further engage students, they could be
challenged to select their own deployment locations and develop,
then validate, current models using their drifter data (Champenois
et al., 2025). Finally, the curriculum could be enhanced by includ-
ing a lesson focused on assessing and quantifying uncertainty in
both measurements and models.
DRIFTER DESIGN MODIFICATIONS
Incorporating environmental sensors, such as those measuring
salinity, temperature, and pH, into the drifter’s custom electronic
stack can capture a broader range of oceanographic data, which
helps contextualize drifter trajectories and contributes to under-
standing ocean processes. Switching to a commercial satellite-
based GPS tracker removes the 4G network range limitation, pro-
viding much larger coverage at a higher cost. Achieving longer
deployments (>1 week) would require a significant redesign, focus-
ing on a more durable frame and drogue, extended battery life, and
a robust communication system. Because this would involve more
permanent materials and a higher cost, drifter retrieval should also
be considered.
OCEAN DRIFTER DEVELOPMENT
AS A TEACHING TOOL
We developed and tested a curriculum to teach undergraduates
and graduate students in oceanography and engineering about
ocean sensor design, ocean sensing, and ocean hydrodynamics.
The project challenged students to design, build, and deploy an
ocean drifter for measuring near-surface ocean currents, as well
as analyze and compare the measured data. The hands-on curric-
ulum was paired with lectures on oceanography, marine robot-
ics, and ocean monitoring. Understanding the movement of drift-
ers required students to engage with the Lagrangian perspective, in
which sensors follow the flow, as they tracked drifter trajectories
to study how ocean currents transport material, in contrast to the
Eulerian perspective that observes stationary points. This hands-on
experience helped them explore real-world processes such as dis-
persion and mixing in coastal environments—concepts central
to physical oceanography.
Students faced several challenges, including limited oppor-
tunities for at-sea testing and deployment due to weather and
ocean conditions. Additionally, limitation in materials and tools
restricted each team to building just one drifter. This single deploy-
ment meant students launched their final designs under condi-
tions that were different from any prior testing. Specifically, winds
and currents were stronger at the deployment location than they
were in the protected harbor used for initial testing. This project
revealed several challenges with remote sensing in marine envi-
ronments. Drifters with higher buoyancy tended to maintain GPS
signal transmission longer by better protecting electronics from
wave impacts. While most drifters followed similar trajectories,
those with deeper drogues or larger surfaces exposed to wind
diverged, illustrating design impacts on current-following perfor-
mance. The custom GPS units may have failed due to degradation
of the water-resistant shellac coatings and coconut wax potting
from saltwater and wind erosion.
The construction and design process was largely student-driven,
with instructors checking in regularly to ensure that teams stayed
on track. For many students, this was their first time deploying
equipment at sea. Instructors provided support by guiding them
through the deployment process, logistics, and design consider-
ations for launching from a boat. In the second week, an addi-
tional lecture on ocean modeling was introduced, which enabled
students to analyze how their drifters’ movements were influenced
by ocean phenomena.
The design challenge proved to be an engaging and educational
experience for the students. In the course evaluation, one student
shared: “It was a great experience to learn material outside of my
degree classes. I feel like I have a much more holistic understand-
ing of marine robotics now that I understand oceanography and
some marine biology.”
REFERENCES
Anderson, T. 2015. Educational experiences in oceanography through hands-on
involvement with surface drifters: An introduction to ocean currents, engineering,
data collection, and computer science. Paper presented at the fall meeting of the
American Geophysical Union, December 14–18, 2015, San Francisco, California,
abstract ED21A–0823, https://ui.adsabs.harvard.edu/abs/2015AGUFMED21A0823A/
abstract.
Beardsley, R.C., and S.J. Lentz. 1987. The Coastal Ocean Dynamics Experiment collec-
tion: An introduction. Journal of Geophysical Research: Oceans 92(C2):1,455–1,463,
https://doi.org/10.1029/JC092iC02p01455.