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1 INTRODUCTION
From the moment of launching, a ship is affected by
external factors. A vessel, performing sea voyages, is
subjected to exploitation, from the technical side as
well as mechanically. The marine environment is
unfavourable to steel. Saltwater, wave motion and
temperature variations have a negative impact on
ship’s metal hull. A constant and challenging issue in
vessel’s operation is the corrosion and biofouling of the
hull and its components, especially submerged
sections exposed to continuous contact with water.
Structures immersed in water, such as ship hulls,
buoys, drilling platforms and pipes, are susceptible to
biofouling by marine organisms. Among them, a
significant group are lichens, which can inhabit
surfaces in both fresh and saltwater. Lichens, a
symbiotic combination of fungi and algae, create
permanent deposits, which over time can affect the
operating properties of the structure, reducing their
hydrodynamics and contributing to the corrosion of
materials [2].
The intensity and rate of microorganism
accumulation on the hull plating are influenced by
many factors of chemical, physical and biological
nature. The entire process is influenced by the climatic
and geographical conditions of the sea area, the
physico-chemical properties of the water and the layers
of the ship's hull. Technical factors characteristic of
each unit also has a significant impact on hull fouling.
Climatic and geographical factors include water
temperature, presence of sea currents, relative water
movement and the degree of solar radiation of the
water body. The most susceptible to fouling are those
structural elements that are most exposed to intense
natural light [7].
The physicochemical properties of the water have a
significant influence on the development of lichen
Modern Methods of Hull Cleaning Using Remote
Operated Vehicle
A. Stateczny, D. Śliwińska & P. Wierzbicki
Gdynia Maritime University, Gdynia, Poland
ABSTRACT: During vessel operation, hulls are subjected to corrosion and biofouling by marine organisms, which
negatively impacts hydrodynamic performance, increases fuel consumption, and elevates operational costs.
Conventional hull cleaning methods typically require dry-docking and involve techniques that may pose
environmental risks. The dynamic development of robotics has facilitated the deployment of Remotely Operated
Vehicles (ROVs) for in-water hull inspection and cleaning, eliminating the need to take the vessel out of service.
ROVs utilize electromagnets to maintain stable adhesion to the ship’s surface, high-pressure water jets to remove
biofouling and debris, and integrated filtration systems to capture and contain contaminants, thereby minimizing
environmental impact. This paper provides a comprehensive review of innovative hull cleaning technologies
employing ROVs, highlighting their advantages over traditional methods and assessing their contribution to
operational efficiency and environmental sustainability.
http://www.transnav.eu
the International Journal
on Marine Navigation
and Safety of Sea Transportation
Volume 19
Number 1
March 2025
DOI: 10.12716/1001.19.01.29
252
organisms as well. The content of nutrients, salinity,
oxygenation level and the degree of pollution of the
aquatic environment are of key importance. Algae, like
many species of marine organisms, develop best in
warm waters with high salinity, which makes vessels
operating in such regions particularly vulnerable to
intensive fouling.
Furthermore, the rate of biofouling settlement and
growth is influenced by technical factors, which may
vary depending on the specifics of a given vessel. The
speed of the vessel plays a key role – slower vessels are
more susceptible to the attachment and accumulation
of organisms on the surface of the hull plating. The
location of the port, the length of stay, the frequency of
inspections and cleaning of the hull and the use of
modern anti-fouling agents are also important. Proper
maintenance and protection of surfaces reduce the
negative effects of fouling, which can lead to increased
hydrodynamic resistance and increased fuel
consumption.
Hull damage or fouling can not only affect the
vessel’s speed and fuel efficiency but can also be
hazardous to cargo and have a negative impact on the
marine environment. It is estimated that a
contaminated hull can increase fuel consumption by as
much as 6% to 14% [6, 10]. Although necessary, hull
inspections can be an extremely difficult task, but they
play an important role in maintaining the operational
efficiency of vessels. Traditional methods of cleaning a
ship's hull can use chemicals that can be harmful to the
marine environment. The rapid development of
robotics and advanced sensor systems is opening new
possibilities for automating this process.
This review article presents the application of
solutions using Remotely Operated Vehicles (ROVs),
as a safe, fast and efficient way to conduct hull
inspections. Furthermore, the study discusses
advanced technologies employed for hull surface
cleaning, which contribute to reduced downtime,
lower maintenance costs, and minimized
environmental impact on the marine ecosystem. The
use of remotely operated vehicles is an innovative
approach that not only improves cleaning processes
but also increases the safety of operations and
contributes to sustainable fleet management. This
publication is organized as follows. Section 2 entitled
"Materials and Methods" presents traditional ship hull
cleaning techniques, which are then contrasted with
modern methods using ROV units, describing the
cleaning process and the tools used. Section 3 entitled
"Discussion" considers the modern cleaning techniques
presented in the article as an alternative to the
traditional stay of the ship in the shipyard dock. The
article ends with general conclusions on the use of ROV
units during underwater hull inspections.
2 MATERIALS AND METHODS
2.1 Traditional cleaning techniques
Conventional hull cleaning is carried out at the
shipyard, where it is necessary to place the ship in a
dry dock. The duration of this period is determined by
the degree of hull fouling, as well as its technical
condition and the scope of shipyard work. On average,
it is from 7 to 10 days. However, such a stay requires
temporary suspension of operations. The main
cleaning technique involves the use of a high-pressure
jet operating at 350 bar. In connection with the above,
together with the removed organisms, loose fragments
of antifouling paint and rust are torn off from the shell.
Certain parts of the hull such as screws, rudder blades,
thruster grids, due to their design, often require
manual cleaning with the use of tools such as scrapers
and brushes. If high-pressure water alone is
insufficient for complete cleaning, sandblasting of the
steel hull surface is performed. This involves spraying
quartz sand at high pressure to effectively remove
deposits from the plating. Use of above-mentioned
technique significantly increases the downtime of the
ship and causes significant pollution of the working
environment. The limitations of traditional hull
cleaning techniques are shown in Figure 1.
Figure 1. Traditional hull cleaning methods – challenges and
limitations [own study].
2.2 Underwater cleaning techniques
The development of technology, robotics and
automation causes traditional methods of cleaning
ship hulls to become less effective and more expensive.
From this perspective, underwater cleaning using ROV
technology has become beneficial compared to the
manual cleaning performed on the shipyard dock [7,
10]. The impact and cost savings results from many
factors, which are presented in the following Figure 2
[3,12].
Figure 2. Advantages of hull cleaning with ROV [own study].
Cleaning the submerged part of the hull using ROV
is based on the use of electromagnets, which ensure
stable adhesion to the steel surface of the ship's plating.
That allows effective cleaning regardless of the
environmental conditions. The system ensures
effective operation even in ports, where the presence of
strong currents, waves and winds could hinder the
operation [1,4,11].
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Due to environmental protection and its
degradation, caused by the release of toxic compounds
into sea waters, global organizations and institutions
have introduced legal regulations regarding the
control of ships and the composition of anti-fouling
coatings. Member states of the IMO (International
Maritime Organization) during the 80th session of the
Marine Environment Protection Committee - MEPC
80) adopted the IMO 2023 Strategy on the Reduction of
Greenhouse Gas Emissions from Ships [5]. With
growing demand on the market, an increasing number
of companies are offering comprehensive underwater
cleaning of the the hull, without the need for dry-
docking.
The time required for an ROV to clean a ship's hull
depends on the vessel type, its dimensions and the
extent of fouling. Approximate time values are
presented on Table 1.
Table 1. Expected operational times [own study based on
[4]].
ROV SERVICE TIMES
The hull cleaning operation involves a barge
carrying all the equipment necessary to carry out the
cleaning. Hence, to ensure the best possible effect and
minimize the operation time, the ship’s sides should
remain accessible to the working unit. The barge
moored alongside the vessel is equipped with all the
necessary equipment to coordinate the hull cleaning
process [10,11]. The ROV is transported and attached
to the ship's hull using a crane mounted on the
workboat. The robot is connected to the barge via cable
reel approximately 150 m long operated remotely
through a control console with joysticks and a
computer interface, enabling precise manoeuvring and
real-time monitoring. The implemented RTS (Robot
Tracking System) allows, continuous tracking, analysis
and optimization of the robot’s movement in real time.
This increases the efficiency of the cleaning process,
extending its range and enables the creation of a "hull
surface map" which, when loaded into the control and
monitoring devices, ensures the performance of
various inspection tasks and thorough cleaning of the
ship's hull. This also enables the control of the water
pressure distribution. The operator stationed on the
barge monitors the robot's route and the condition of
the hull. The system is capable of functioning even in
limited visibility caused by poor water clarity. When
encountering greater contamination, the operator can
adjust the water pressure as needed, up to 350 bar. The
barge is equipped with a filtration system that allows
automatic processing of collected waste. In this
process, removed biofouling is separated into a
designated bag, while the clean, filtered water returns
to the ecosystem.
The average dimensions of the cleaning platform
are: 2m x 1.8m x 0.6m. While ensuring its solid
installation with the ability to work in difficult port
conditions, there are certain limitations in the scope of
cleaning the underwater part of the hull.
The areas inaccessible for the robot depend on the
type of ship and its size. These areas are checked
separately, with the involvement of a qualified diver.
They mainly include such sections as [4,9]:
− Areas with protrusions: bilge keel, anodes;
− Bow and stern thruster’s surroundings, sea chest
and other hull openings;
− Significantly curved surfaces: bulbous bow,
propeller area and rudder blade.
In Figure 3 the inaccessible areas are marked by
yellow.
Figure 3. The impassable areas on hull surface [4].
Table 2 outlines the constraints necessary for the
correct operating conditions of the ROV. Compliance
with the below mentioned constraints allows for
appropriate adjustment of the cleaning technology to
the operating conditions of the vessel, ensuring
operational effectiveness and minimizing the potential
risk of damage.
Table 2. Hull cleaning constraints [own study based on [4]].
Removal of fouling around the waterline
up to 1 meter
Ability to clean surfaces with curvature
up to 2.5 meters
Minimum clearance under the vessel's
keel
1.5 meters
Minimum clearance between vessel and
quay
2 meters
2.3 Dry dock cleaning techniques with ROVs
With the development of technology, the use of ROVs
has been extended to vessel maintenance during the
dry docking. Traditional methods, such as
sandblasting, scraping or high-pressure washing,
require direct involvement of shipyard personnel and
are associated with high operational costs and impact
on marine ecosystems [2]. Cleaning robots developed
by Vertidrive - a company that creates safe,
environmentally friendly and cost-effective solutions
in the field of crawler robots, are an innovative
approach to the maintenance of hulls during dry
docking [12].
According to the manufacturer’s website, the three
latest ROV machines - VertiDrive M3 (Fig. 4.),
VertiDrive M4 (Fig. 5.) and VertiDrive M7 (Fig. 6.), not
only speed up work efficiency (up to eight times faster
depending on the model), but also reduce cleaning
costs from 86% to 92% compared to the conventional,
manual hull cleaning. This results in significant savings
of both time and resources. As stated by the
manufacturer: "All of the previously mentioned
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VertiDrive solutions are hull blasting robots that have
been designed to clean vessels with maximum
productivity and minimal operational costs. Each
function as a carrying platform for traditional hand-
held blasting equipment, an operator simply needs to
connect the robot to the hose line of a hand-held
blaster, and they are ready to work. Important to note
is that the operator will always be located safely on the
ground, far away from any ship hull maintenance
related hazards.
These ship hull cleaning robots can be used for ship
anti foul removal within a dry dock cleaning scenario.
Horizontal, vertical, curves, corners and overhead
surfaces are all a breeze for these robots through the
use of permanent, powerful magnets.” [12]
Additionally, delving into the descriptions of
individual machines reveals valuable information
useful for selecting the most suitable equipment for
hull cleaning operations.
Figure 4. VertiDrive M3 machine [12].
The ease of operation, as well as the
comprehensiveness of the services provided,
demonstrates that hull cleaning devices are
increasingly taking the lead as tools that enhance ship
maintenance processes. The ability to quickly adapt the
devices makes these systems an efficient solution,
whether for cleaning standard hull sections or hard-to-
reach areas: “In addition to the perks […] already
mentioned, the M3 is an exceptionally simple blasting
robot to disassemble. This makes for much easier
access to spaces such as manholes and other confined
spaces. Interchanging the M3 with the VertiDrive M4
is also possible with the help of the M3 – M4 conversion
kit, which allows an operator to make use of the M4's
specialized hydro blasting capabilities.” [12]
Figure 5. VertiDrive M4 machine [12].
The efficiency of hull cleaning may depend on
many factors, such as the impact of the process on the
environment, the power of the device or the
maintenance stages. Modern machines have a
significant impact on increasing work efficiency and
reducing negative impacts on the environment, which
is emphasized by the technical description of one of the
machines: “The M4 is a closed hydro blasting solution.
In combination with the VertiDrive Vacuum System
the surface worked upon will dry immediately thus,
preventing flash rust and reducing environmental
waste. This also enables other technicians to
simultaneously perform other maintenance work,
contributing to significant time savings to bring the
asset earlier back into service.” [12]
Figure 6. VertiDrive M7 machine [12].
Cleaning large surfaces with curved designs
requires great precision, as well as appropriate power,
which should also be accompanied by mobility.
Modern devices for cleaning ship sides allow for
efficient work even in the most difficult conditions.
3 DISCUSSION
The solutions presented in the article, which utilize
unmanned vehicles for hull cleaning have the potential
to become a standard in modern shipping and its
sustainable operation.
Although the solutions described in the article may
involve high initial cost, they offer numerous
compensating advantages:
− Cleaning can be performed during cargo operations
in port, along with other port activities such as
bunkering, garbage collection or fresh water
supply. It is also possible to carry out cleaning
operations while the vessel is underway at low
speed;
− No additional, costly vessel downtime;
− The ROV is unmanned, making the operation
fundamentally safe;
− Hull cleaning is carried out using a high-pressure
water jet with fully adjustable and controllable
pressure, with a range between 25 and 350 bar;
− The cleaning process has a minimal impact on the
coating because the robot does not use scrubbing
brushes;
− The removed contaminants are collected in a
separate container located on the barge moored
alongside and then safely disposed of in accordance
with environmental regulations;
− The robot is capable of navigating along the
waterline as well as curvature of the hull;
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Upon completion of hull cleaning, the vessel emits
less GHG (Greenhouse Gas) during operation due to
improved hydrodynamics performance.
4 CONCLUSION
Operational efficiency, fuel consumption and
environmental impact are key aspects of hull
cleanliness. While traditional manual methods of
removing biofouling and maintaining debris-free hull
still remain widely used, they are also expensive, time-
consuming and have a negative impact on the marine
environment.
In response to this niche in hull maintenance, many
companies have developed ROV systems that not only
clean but also inspect the submerged part of the hull.
The use of ROVs enables hull maintenance in most
cases without the need to interrupt the vessel’s
operation, which significantly reduces both
operational and financial losses.
Advanced, electromagnetic adhesion systems,
combined with precision control technologies and
high-pressure water cleaning, allow minimal to no
damage of the hull's protective coating. Additionally,
integrated filtration systems allow for limiting the
negative impact on the marine ecosystem.
In conclusion the use of ROVs in the automation of
ship hull cleaning is a fundamental step towards more
efficient use of sea and ocean shipping, as well as
greater environmental responsibility.
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