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1 INTRODUCTION
The initial phase of this research, as outlined in the
preceding work [1], focused on the conceptualization
and development of a safe beach zone system. This
system was designed to improve coastal safety through
the deployment of smart buoys equipped with
specialized sensors. The buoy design was meticulously
engineered to meet specific operational requirements,
emphasizing modularity and manufacturability using
3D printing technology [9], [5]. Critical parameters of
the buoys, as well as the coastal station, were
rigorously calculated to ensure optimal performance.
Additionally, the system’s electrical characteristics
were analysed to guarantee reliability and efficiency.
Following the design and computational phases, two
fully functional buoys and a coastal station (Fig. 1)
were successfully fabricated.
By integrating IoT into this smart buoy system, real-
time data on water conditions, weather patterns, and
swimmer safety can be continuously monitored and
seamlessly communicated to lifeguards and beach
visitors. The success of such a system depends on an
intuitive and user-friendly design, allowing
individuals without technical expertise to engage with
its functionalities effortlessly. IoT serves as the
cornerstone of this innovation, enabling seamless
connectivity, data sharing, and automation.
Prioritizing IoT integration in critical safety solutions
such as smart buoys highlights its potential to enhance
life-saving measures while fostering the development
of more intelligent, secure, and interconnected
environments.
The subsequent phase of this project involves
comprehensive hardware testing to validate the
system's durability and functionality under realistic
Design and Implement an Automatic Smart Buoy
System for a Bulgarian Safe Beach Areas – Part 2
I. Dimitrov
1
, I. Iliev
1
, D. Hristov
1
, D. Dinkov
1
& T. Mavrodiev
2
1
Nikola Vaptsarov Naval Academy, Varna, Bulgaria
2
Technical University of Munich, Munich, Germany
ABSTRACT: The Internet of Things (IoT) is undergoing rapid expansion, transforming industries and everyday
life through interconnected devices and data-driven decision-making. As IoT adoption accelerates, ensuring its
accessibility and usability for non-technical users becomes increasingly critical. Simplified interaction with IoT
systems facilitates broader adoption and maximizes their potential to improve safety, efficiency, and convenience.
This aspect is particularly crucial in the domain of coastal safety, where IoT technologies can play a pivotal role.
By integrating IoT into a smart buoy system, real-time data on water conditions, weather patterns, and swimmer
safety can be continuously monitored and seamlessly communicated to lifeguards and beach visitors. The
effectiveness of such a system relies on an intuitive and user-friendly design, enabling individuals without
technical expertise to engage with its functionalities effortlessly. IoT serves as the foundation of this innovation,
providing seamless connectivity, data sharing, and automation. Prioritizing IoT integration in critical safety
solutions such as smart buoys underscores its potential to enhance life-saving measures while contributing to the
development of more intelligent, secure, and interconnected environment.
http://www.transnav.eu
the International Journal
on Marine Navigation
and Safety of Sea Transportation
Volume 19
Number 2
June 2025
DOI: 10.12716/1001.19.02.06
388
environmental conditions. A series of stress tests [10]
were conducted to evaluate the physical resilience of
the buoy casings and their ability to withstand harsh
marine environments. These tests were performed in a
controlled setting at the Sea Survival Centre of the
Nikola Vaptsarov Naval Academy, where the buoys
were submerged in a deep-water pool for five days.
Additionally, the facility’s wave-generating apparatus
was employed to simulate dynamic wave conditions,
offering valuable insights into the system’s
performance under realistic maritime stresses. Footage
and video documentation of these wave simulations
are available for reference [4].
This testing phase represents a crucial step in
ensuring the system’s reliability and operational
readiness for real-world deployment. The insights
gained contribute significantly to the enhancement of
coastal safety measures, reinforcing the role of IoT-
driven smart buoy systems in creating safer and more
resilient maritime environments.
2 ASSEMBLY PROCESS
The assembly process of the smart buoy commences
with the 3D printing of the hull and inner container.
These components provide a durable structural
foundation and serve as enclosures for the onboard
electronics. Following the printing phase, the buoy is
painted yellow in compliance with national and
international maritime regulations, enhancing both
visibility and safety in marine environments. To
further protect the system, protective coating layers are
applied to the exterior surfaces, ensuring corrosion
resistance and waterproofing. This protective layer
prevents water ingress, safeguarding the buoy’s
internal electronics and contributing to the system’s
long-term operational reliability.
Figure 1. Smart Buoy Prototype (left) onshore station (center)
It is important to note that materials used in the
buoy's construction are environmentally friendly,
posing no threat to biodiversity or the marine
ecosystem.
The next step is the integration of electronics, which
involves the installation of contact pins, wiring, and
other essential components (Fig. 2 and Fig. 3).
Figure 2. An internal view of the container. The layout of the
electronics and wiring
Figure 3. Contact pins between the solar panels and the
interior of the buoy
The assembly process of the buoy follows a
structured approach similar to the operational
methodology of a 3D printer. During this phase, the
electronic components and individual plastic elements
are systematically integrated. The process continues
until the solar panels are securely affixed, the sealing
mechanism is properly installed, and the O-ring along
with the cover is precisely positioned. This meticulous
assembly ensures structural integrity, water resistance,
and the long-term reliability of the buoy in marine
environments.
3 EXPERIMENTAL SETUP
To assess various parameters and analyse the
operational behaviour of the constructed system -
comprising smart buoys and the coastal receiving
station - a dedicated test setup was established, as
illustrated in Fig. 4. This experimental configuration
enables systematic evaluation under controlled
conditions, ensuring the system’s reliability and
performance in real-world maritime environments.
Prior to conducting the actual experiments, the
communication range of the BLE system was evaluated
both empirically and experimentally. The results
indicated that the system operated without
interruptions within a range of 50 meters. However,
the buoy's casing significantly attenuated the module’s
effective range, reducing it from the documented 200
meters.
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Figure 4. Experimental setup scheme
Testing confirmed that a stable connection between
buoys is maintained at a distance of 50 meters, which
aligns with the system's operational requirements. In
real-world maritime deployments, the spacing
between adjacent buoys should not exceed this range.
For applications requiring extended coverage, the
communication module can be replaced with a more
suitable alternative, such as LoRaWAN [7] or
Raspberry Pi [3].
Nevertheless, the established communication range
is sufficient for deploying buoys to delineate a
designated safe beach zone. Following the successful
assessment of the system's communication channel,
anchors were manufactured (Fig. 5) to secure the buoys
in position. The anchor’s weight, dimensions, and rope
length were carefully pre-determined to ensure
stability while accounting for the buoy’s flotation
characteristics.
The system was deployed within a controlled test
environment at the Sea Survival Centre of the Nikola
Vaptsarov Naval Academy to evaluate its performance
under realistic maritime conditions. The specialized
pool is equipped with a wave generator able to
simulate realistic sea environment with wave height of
up to around 0.9 meters.
Figure 5. Smart Buoy (in yellow) prepared for the setup and
specially designed anchor (bottom right)
In addition to the other tests, it was confirmed that
the buoys maintained their buoyancy and effectively
prevented any water from penetrating the electronics
and internal compartment. By the fifth day of
operation, the battery of one buoy had been completely
discharged. Upon analysing the data, it was
determined that this particular buoy was positioned
too close to the pool wall, where sunlight could not
adequately reach the solar panels (Fig. 6). This
observation highlights the importance of proper buoy
placement to ensure optimal solar panel performance
and battery life.
Figure 6. General view. In the background the buoy located
near the pool wall
After positioning the buoys at the maximum
feasible distance, the system was activated, and the
initialization process for the buoys commenced. The
control station, used for monitoring and analysing
traffic, successfully received data regarding the buoys
and the functionality of their sensors.
Upon successful initialization, the system
transitioned to actively transmitting data from the
sensors to the coastal station while simultaneously
streaming the data to an open-access internet platform
and cloud database. During the test, wave fluctuations
and water temperature (°C) were measured. The
results of these measurements are presented in Fig. 7.
4 DATA PROCESSING
After the successful transfer of data from the buoys to
the station device, the raw IMU data must undergo
further processing and analysis to extract valuable
information about the waves. This includes key
parameters such as wave height (h), period (T), speed
(V), and direction of propagation.
Figure 7. Temperature and raw wave data measurement
results
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First, the data must be filtered and prepared for
further processing. This involves using a low-pass filter
for acceleration measurements and a complementary
filter, which is specifically tuned to combine data from
the accelerometer and gyroscope to estimate the tilt
angle of the buoy. Once the tilt angle is calculated, it
allows for the isolation of the pure acceleration
responsible for the periodic motion by subtracting the
gravitational component from the filtered
measurements.
To effectively analyse periodic measurement data,
spectral analysis is the most common and efficient
approach. Therefore, the authors opted to use the
discrete fast Fourier transform (FFT) algorithm [6] to
convert the filtered accelerometer data into its
frequency domain representation. This enables the
calculation of the wave height distribution in the
frequency domain using the following relationship [6]:
(1)
Without loss of generality, it can be assumed that φ = 0
for the sake of simplifying calculations, as this
assumption does not affect the final result of interest —
the amplitude of the complex signal
.
Figure 8. Wave height distribution H[f] in the frequency
domain
The graph clearly shows three main peaks,
corresponding to the primary frequency of the
generated waves at 0.2 Hz and its harmonics.
Therefore, the period of the main component of the sea
wave can also be calculated.
Subsequently, an error-state Kalman filter [2] with
Rauch-Tung-Striebel smoothing [8] is applied to the
raw IMU data for trajectory estimation, which is crucial
for further calculating the length and velocity of the sea
wave. Knowing the relative tilt angle and the fact that
the trajectory follows an elliptical shape, an algorithm
is used to detect the section of the trajectory
corresponding to the wave crest, or the "forward"
movement, and determine the cardinal direction of
propagation.
5 DATA STORAGE, AGGREGATION AND
DISTRIBUTION
During the tests and experimental setup, the device
used at the edge (Raspberry Pi 5), simulating the
coastal station, demonstrated the computational
capability to run all the necessary data processing
algorithms in real time. This made it a critical
component in the communication hierarchy,
responsible for both processing and distributing the
data collected from the buoys. In a more realistic
deployment scenario, this device would be replaced
with a less powerful alternative to reduce energy
consumption. The data received at the edge device
would be further aggregated before being transmitted
through the uplink to the backend, thereby helping to
minimize the bandwidth requirements for this
connection.
As a complementary feature to this IoT
infrastructure, a backend application programming
interface (API) was developed to provide other
researchers with access to the data. The API offers both
free and authenticated access to the database
containing raw and processed data. The underlying
technologies include a simple HTTPS web server
implementing a REST architecture, accessible over the
internet, a MySQL database hosted in a cloud
environment, and an intuitive HTML/CSS-based
frontend application. The authentication system is
implemented through API tokens, which are issued to
users by an authentication server.
6 RESULTS
The implementation of the smart buoy system, as
demonstrated in this study, highlights its considerable
potential for improving port operations. This specific
application illustrates the system’s ability to
autonomously collect real-time data, leading to
significant time and cost savings. More importantly, it
provides users with comprehensive and relevant
information critical for evaluating maritime safety and
optimizing port efficiency. The successful deployment
of this system emphasizes its practical advantages,
including enhanced decision-making, improved
situational awareness, and increased operational
reliability. These results confirm the value of
integrating smart buoy technology into port systems,
presenting a proven solution for modernizing
maritime infrastructure and ensuring safety.
7 DISCUSSION
The authors’ conceptual framework for developing a
beach safety zone system is structured across three key
phases, each detailed in a dedicated publication. The
first phase encompasses the inception of the idea and
the creation of the project, providing a foundation that
outlines the rationale, objectives, and initial design
considerations. The second phase delves into the
hardware and software implementation, followed by
extensive testing within a controlled environment to
ensure operational stability and performance integrity.
The final, forthcoming phase aims to deploy the
system in a real-world beach environment during a
suitable tourist season, specifically within a coastal
area managed by the Nikola Vaptsarov Naval
Academy (NVNA). This conclusive stage is pivotal,
focusing on the acquisition of environmental data,
evaluation of the automated flag display mechanism,
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stress testing the web application under high user
loads, and verifying system resilience in scenarios
involving communication loss between individual
buoys.
The culmination of these efforts is expected to
provide empirical insights into the system’s
operational robustness, ensuring that it meets the
demanding conditions of a dynamic maritime
environment. This holistic approach integrates marine
technology, safety protocols, and real-time data
acquisition, fostering a comprehensive and scalable
solution for enhancing beach safety zone management.
8 CONCLUSIONS
The smart buoy system represents a transformative
advancement in maritime technology, demonstrating
significant potential to revolutionize maritime
operations, particularly in port approaches and basins.
By leveraging IoT technology, the system enables
continuous and automated data collection on maritime
traffic and environmental conditions, providing real-
time insights that enhance navigational safety,
ecological standards, and operational efficiency. The
system’s flexibility allows for seamless integration into
a wide range of port infrastructures, adapting to
specific operational needs across various maritime
environments.
One of the key strengths of the system is its
adaptability. The smart buoys can be customized for
different environmental and operational contexts,
making them suitable for diverse maritime challenges.
The system’s design also supports integration with
other IoT technologies and automated systems in ports,
such as automated cargo handling or weather
forecasting systems, further enhancing port efficiency
and safety.
The smart buoy system has shown its ability to
operate effectively under challenging environmental
conditions, including sea waves, with real-time
monitoring providing valuable data for improving
maritime safety, optimizing traffic management, and
conducting environmental assessments.
Additionally, with the proper deployment of
sensors, the system plays a critical role in detecting
illegal activities such as unauthorized anchoring and
fishing, supporting pollution monitoring, and assisting
in port area inventories. The data collected can also
contribute to scientific research, maritime studies, and
risk assessments, further underscoring the system's
versatility.
Designed with energy efficiency in mind, the
system utilizes solar panels and other sustainable
energy sources, ensuring long-term operation without
compromising performance. The energy consumption
has been optimized to meet modern sustainability
requirements, making it a reliable solution for
environmentally conscious deployment.
In conclusion, the smart buoy project sets a strong
foundation for future innovations in smart maritime
systems. Its ability to provide reliable, real-time data,
coupled with its adaptability and energy efficiency,
makes it an invaluable tool for enhancing safety,
sustainability, and efficiency in maritime operations,
paving the way for safer and more sustainable seas.
In the next article, the research team will provide
data not only from experiments conducted in a
controlled environment but also from the real-world
deployment of the system in one of the beach zones in
the Varna Bay, Bulgaria. This will offer valuable
insights into the system's performance and
effectiveness under actual operating conditions.
ACKNOWLEDGEMENT
This research paper has received funding from project “Safe
beach zones” sponsored by Nikola Vaptsarov Naval
Academy.
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