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Article Not peer-reviewed version
Design Considerations on Semi-
submersible Columns and
Pontoons for Floating Wind
Glib Ivanov * , I Jen Hsu , Kai-Tung Ma
Posted Date: 10 July 2023
doi: 10.20944/preprints202307.0643.v1
Keywords: Floating Wind; FOWT; Hull design; Wave load; Bracing; Structural Analysis; Manufacturing;
Offshore Wind; Renewable Energy; Optimization
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Article
Design Considerations on Semi-Submersible
Columns and Pontoons for Floating Wind
Glib Ivanov * and I Jen Hsu and Kai-Tung Ma
National Taiwan University; ijenhsu@ntu.edu.tw (I.J.H.), kaitungma@ntu.edu.tw (K.T.M.)
* Correspondence: f10525106@ntu.edu.tw
Abstract: Floating Offshore Wind Turbine (FOWT) is an innovative technology with little industry
guidance for its hull design. Various FOWT floaters with different hull shapes claim to support the
same turbines. Structural integrity and material expense analyses of different pontoon shapes were
conducted, and it was found that some configurations, such as those with every two columns
connected by both pontoon and bracing, have advantages over others. However, it is important to
note that the choice of pontoon shape should be based on the wave loading conditions the floater
will be exposed to. While a T-shaped pontoon provides a cost-effective solution under certain wave
loading scenarios, it may not be the best option for all conditions. Specifically, ring pontoon designs
with full bracing were found to be necessary for withstanding certain wave loads. Therefore, it is
important to consider different Dominant Load Parameters (DLP) and ensure that a FOWT floater
can withstand all applicable DLPs. An uneven hexahedral column shape, which combines the best
attributes of square and round shapes, is proposed as a better alternative to cylindrical columns. It
offers ease of manufacture and reasonably low drag. Bracing is found to be necessary for
withstanding the wind turbine’s incurred moment and forces. The conclusion is that platform
design should prioritize manufacturing costs and strength over maximizing hydrodynamic
performance.
Keywords: Floating Offshore Wind Turbines; FOWT; hull design; wave load; bracing; structural
analysis; scalability; manufacturing; offshore wind
1. Introduction
Recently, there are many different semi-submersible Floating Offshore Wind Turbines designs
introduced to public attention [1]. As with every new technology, it is uncertain which option is the
best, only with time natural evolution will strike out the inefficient designs and standardize the
invention to some extent. Regarding semi-sub FOWT, some configurations have already shown their
superiority, such as tri-column design and off-center turbine placement, as proven by
commercialized projects. However, other parts of the semi-sub design are still highly debated, such
as how the pontoon should look and the optimal column shape.
Among current and planned projects by different companies and research teams (Figure 1.1),
there are L-shape (Fukushima Shinpuu) [2], T-shape (Bassoe T-floater) [3], above water pontoons
(Gusto Tri-Floater old version) [4], tubular joints (WindFloat) [5] and ship-like hull pontoons
(DeltaFloat) [6], platforms with and without above-water bracing (EOLFI floater [7], Fukushima
Shinpuu), platforms with bracing bigger than pontoon (SanXia YingLing Hao) [8], and so on. It is
evident, that every design team drafts their design with particular constraints and necessities in mind,
however as most are made by for-profit companies, not much of their thought process is shared with
the general public.
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from any ideas, methods, instructions, or products referred to in the content.
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© 2023 by the author(s). Distributed under a Creative Commons CC BY license.
2
Figure 1.1. Different designs of semi-submersible hulls for FOWT.
As researchers, we take the liberty to analyze and compare them without bias. With so many
varieties, it is clear that some are to be outlived by the more efficient. The parts specifically looked at
in this paper are the different pontoon, column and to a lesser extent, bracing configurations.
Pontoon and bracing have a practically similar purpose – to hold the columns together for them
to make up a platform. In designs like Wind Float, they are practically the same, the only difference
being pontoon is located underwater, while the bracing is above water. Bracing also provides a way
for workers to walk between the columns.
The pontoon is filled with ballast and thus brings the platform’s center of gravity down, if its
vertical footprint is big, it also acts as a heave-damping plate. Sometimes, it can also provide
buoyancy as will be described later
2. Design Methodoligy
To compare different pontoons, eight (11) modifications of a base platform were created in
ANSYS SpaceClaim, shown as the shapes A. to K. in Figure 1.2. The original triangular ring pontoon
platform is an updated version of TaidaFloat [9], a prototype platform to be used in Taiwan strait.
While TaidaFloat pontoon can be fully functional (provide buoyancy) or partially functional
(permanently ballasted), to remove the influence of wildly varying buoyancy between the different
pontoons, they will be considered only partially functional. The other dimensions including all
column dimensions, as well as overall length and width are the same among designs, shown in Table
2.1. The platform supports a 15 MW IEA turbine [10,11], with the following characteristics shown in
Table 2.2. The platform also takes some ballast in columns for use in a dynamic stabilization system
and to achieve the desired draught.
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Figure 1.2. Different pontoon and bracing arrangements.
Table 2.1. TaidaFloat’s principal characteristics.
Length 81.6 m
Breadth 94.2 m
Height 35 m
Draught 22 m
Total displacement ±20 300 t
Hull weight 4002 t
CG height 17.35 m from BP
Coordinates Origin Pontoon centroid at base plane (BP)
Table 2.2. Wind turbine characteristics.
Name IEA 15 MW
Roter orientation,
Configuration
Upwind,
3 Blades
Rotor Diameter 240 m
Hub height 150 m
Blade mass 65.25 t
Tower mass 1263 t
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RNA mass 991 t
For every configuration, turbine, ballast and platform assembly weight characteristics including
mass moments of inertia were calculated using ANSYS Mechanical, they are shown in Table 2.3.
Table 2.3. Design cases mass characteristics.
Case A B C D E F G H
System mass (t) 19450 19450 20920 16410 16789 16750 16750 16612
Center of mass,
CM (m) (X,Y,Z)
(0, 6.231,
18.803)
(0, 6.276,
18.278)
(0, 3.749,
19.358)
(0, 8.5149,
22.061)
(0, 6.629,
21.908)
(0, 10.004,
21.173)
(0, 10.017,
21.306)
(0, 0.822,
24.620)
Principal
inertias
about CM
(kg m
2
)
I
xx
0.5335E+11 0.5330E+11 0.5301E+11 0.4868E+11 0.5218E+11 0.4696E+11 0.4702E+11 0.4950E+11
I
yy
0.4931E+11 0.4923E+11 0.5037E+11 0.4438E+11 0.4460E+11 0.4647E+11 0.4632E+11 0.4984E+11
I
zz
0.2833E+11 0.2816E+11 0.3015E+11 0.2306E+11 0.2456E+11 0.2541E+11 0.2529E+11 0.3178E+11
I
xy
-0.6734E+06 -0.6725E+06 -0.1504E+07 0.2873E+07 0.1138E+07 0.1171E+08 0.1172E+08 0.3347E+07
I
xz
-0.3047E+07 -0.3057E+07 -0.3480E+07 0.1343E+08 -0.1606E+07 0.4037E+07 0.4086E+07 0.1330E+08
I
yz
-0.9954E+10 -0.1003E+11 -0.1040E+11 -0.9048E+10 -0.1004E+11 -0.8096E+10 -0.8003E+10 -0.1068E+11
Every design case should be analyzed for the following results:
• Strength
• Stability
• Costs
• Exploitation
This paper focuses on strength and cost only. Stability and exploitation may be tackled in future
research.
Nowadays, the common approach is to analyze the structural strength of a large number of
designs with FEM. ANSYS Mechanical was used for this purpose here. Hull weight and mass
moments of inertia were calculated with a framed, ship-like, inner structure. The inner structure is
based on the original inner structure for configuration A, slightly modified to fit the shape in other
cases. It is shown in Figure 2.1.
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Figure 2.1. TaidaFloat dimensions, structural arrangement and axes.
As the first step, all the configurations were subjected to static loads – gravity, water pressure
(fully ballasted pontoon condition), turbine assembly weight and a 0.1G acceleration in x and y
directions to approximately account for the wave loads.
It is not surprising, that every configuration successfully withstands these static loads, with no
important difference between different designs. An example of the result is shown in Figure 2.2
Figure 2.2. TaidaFloat static FEM analysis.
The actual difference among the 12 pontoon designs can only be seen during its operation in the
rough sea, with dynamic loads. According to ABS Rules [12], and other major class societies’ rules
[13–15], offshore structures’ dynamic performance is to be analyzed with different DLP (Dominant
Load Parameters) and DLC (Design Load Cases). They represent a comprehensive array of
parameters such as wind, loading, waves applied together in the most unfavorable combinations
(DLC), and their effect on particular structure parts and modes of deformation (DLP).
For a structure such as a FOWT floater, the matrix of DLP and DLC combinations reaches more
than one hundred cases. For 8 pontoon configurations analyzed in this paper, that would be about a
thousand cases to investigate. However, not all cases are equally important, here we use engineering
judgement and compare 8 cases’ performance at critical DLPs and roughest wave load DLC.
The most critical is arguably the DLP 1 when the wave front is along the platform’s X axis, then
one side column is on the wave top, another side column in the crest, and the main column is at the
middle height, as shown in Figure 2.3. Difference in buoyancy forces between the two columns
produces a twisting moment on the pontoons linked with the main column, potentially breaking
them.
Figure 2.3. Wave-induced twist – DLP 1.
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DLP 2, shown in Figure 2.4., is when the wave front approaches along the Y axis, the main
column on the wave top and both side columns in the crest, or vice versa.
Figure 2.4. Wave-induced shear DLP 2.
DLP 3’s wave condition is similar to DLP 1, however here bending moment is considered not
enough to break the platform and horizontal shear is analyzed instead.
3. Pontoon design
For this part of the study, simplified models were used, which had a uniform plate thickness of
30 mm and no reinforcement, except for bulkheads. The force application areas were kept rigid using
coupled multi-point constraints. The adequacy of this simplification was demonstrated in a previous
study. [9]
The eight configurations were analyzed according to DLP 1 conditions, and it was found that
the configurations with a 3-part pontoon outperformed those without (L-G-H) by a large margin, as
shown in Figures 3.1 - 3.3. Configuration A, with its firmly connected structural members, was found
to be the most resistant to wave-induced torsion. Configuration C showed similar results, although
there was some stress concentration on the inwards-facing side of the side column. Configuration B
exhibited good resistance to torsion at the main column, but had large areas of stress concentration
in the connection area between the pontoon and columns. Case F exhibited similar phenomena,
which was common for all cases without full bracing. This confirms the necessity of bracing, which
prevents column rotation relative to pontoons and distributes part of the pontoon's tension.
Figure 2.5. Horizontal shear DLP 3.
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A. Ring pontoon with bracing B. Triangular ring pontoon
C. Triangular Ring 45 deg. pontoon with
bracing
D. Y-shape pontoon with bracing
Figure 3.1. Cases A-D DLP 1, stress plot.
E. T-shape pontoon with bracing F. L-shape pontoon with 2 braces
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G. L-shape pontoon with 3 braces H. Y-shaped bracing without pontoon
Figure 3.2. Cases E-H FEA DLP 1, stress plot.
I. Y-shape bracing with small pontoon J. Tubular joints
K. L-shape pontoon with no braces L. Y-shaped pontoon, central column
Figure 3.3. Cases I-L FEA DLP 1, stress plot.
For configuration E, it was found that the T-shaped pontoon can resist torsion almost as well as
ring-shaped pontoons, but with considerably less metal used. Cases A(C), B, and E that successfully
resisted DLP 1 torsion were further analyzed under other loads.
The stress distribution for DLP 2 and DLP 3 FEA is shown in Figure 3.4. Although the T-shaped
pontoon performed well in resisting DLP 1, it exhibited high-stress areas around its middle pontoon,
bracing connections, and pontoon intersection corners under DLP 2 and DLP 3. This is because the
load is mainly carried by the middle pontoon in a T-shape when the main column is on the wave
peak, while in a ring shape, it is borne by two pontoons of the same dimensions. The need for bracing
is further confirmed in case B under DLP 3, where a side pressure on the column resulted in a large
deformation of the pontoon, causing stress concentrations five times higher than in the same pontoon
with bracing (case A), where bracing prevented the rotation. Table 3.1 provides the average and
maximum stresses and the relevant shape's hull weight for perspective.
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A. Ring pontoon with bracing, DLP 2 E. T-shape pontoon, DLP 2
A. Ring pontoon with bracing, DLP 3 B. Ring pontoon, DLP 3
J. Tubular joints, DLP 2 L. Y-shaped pontoon with central
column, DLP 2
Figure 3.4. Cases A,B, E; DLP 2,3, stress plot.
Table 3.1. Weight (detailed model) and stress (simplified model).
Case Hull weight,
tones
Average stress
DLP 1, MPa
Max. stress
DLP 1, MPA
Max. stress
DLP 2, MPA Max. stress DLP 3, MPA
A 4002 17 210 270 424
B 3674 20 260 - 1159
C 4424 14 233 - -
D 3493 20 391 - -
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E 3597 18 238 418 -
F 3444 32 275 - -
G 3561 22 355 - -
H 3232 26 915 - -
I 3694 20 446 - -
J 3764 8 168 405 -
J2 6124 5 104 323 -
K 3313 32 712 - -
L 2733 20 101 953 -
Table 3.1 in the paper shows that platforms with similar hull weights can have vastly different
structural performances. Although their average stress is not significantly different, the maximum
stress varies greatly under the same load (DLP 1), ranging from 72 to 915.
This indicates that some shapes have severe stress concentration areas compared to others.
The best and worst performers in each category are denoted by green and red colors,
respectively. Interestingly, some platforms are the best in one category but the worst in another (cases
H and L). Additionally, some platforms can withstand DLP 1 with lower stress than full bracing and
pontoon configurations, but they may fail under other DLPs. The advantage of full configurations is
that they perform sufficiently well under different DLPs, which is important since conditions at sea
and during transportation can be unpredictable.
Note that the exact value of maximum stress may differ if a high-detail model were analyzed,
but the table still provides a useful comparison of the structural performances of different platform
shapes.
The strength of a structure can be measured by its average stress. A shape called J with tubular
joints connecting columns is the strongest performer, with well-distributed loads. However, making
tubular joints is complicated because they are round and need to connect to straight walls and each
other. This causes high stress in connection regions, but this is not a problem if the columns, pontoon,
and bracing intersect at right angles and their internal stiffeners align perfectly.
Although J is strong, it is heavier compared to other shapes with smaller pontoon and bracing
configurations. The lightest shape is H with Y-shaped bracing and no pontoon, but it has high stress
of almost 1000 MPa under DLP 1. This means it would need to be strengthened a lot, which negates
its weight economy. A shape called L with a circular central column is excluded from the weight
comparison because it's a different breed of structure. Interestingly, it performs exceptionally well at
DLP 1 but fails the worst at DLP 2.
An experiment was done on J by increasing the hull thickness to 40 mm and the tubular joints
to 60 mm, making a new shape called J2. Its maximum stress was closer to that of shape A at 323
MPa, which could be made equal to A's stress with connection reinforcement. However, J2 was
heavier, weighing 6124 tons, which is 53% heavier than shape A.
4. Column design
In most of the cases presented above, the columns of the semi-submersible floater are
hexahedral, while in others they are cylindrical. This raises a question about why the hexahedral
shape was chosen. To understand this, it's important to know that the columns of a semi-submersible
floater serve three main functions:
• supporting the wind turbine;
• providing stability;
• providing buoyancy.
Changing any aspect of the column to improve its performance in one function will affect its
performance in the other two functions as well. Therefore, a complex balancing process is required
to optimize the design of the columns.
At the moment, the FOWT industry has two types of column designs, as shown in Figure 4.1
and Figure 4.2:
Round (e.g. WindFloat designed by Principal Power) [5]
Square (e.g. Shinpuu designed by Fukushima Project) [16]
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Figure 4.1. Round columns of WindFloat (Picture Courtesy of Principle Power Inc.).
Figure 4.2. Square columns of Fukushima Shinpuu (Picture Courtesy of Fukushima Offshore Wind
Consortium).
Table 4.1 lists the advantages and disadvantages of circular and polygonal cross-section
columns. Since they are two opposite shapes, it makes sense that the optimal design would be
somewhere in between. To create a column that approximates the circular shape while only using
straight plates, a polygonal cross-section column is used.
Table 4.1 Comparison of cylindrical and square columns.
For TaidaFloat, which has three columns and three pontoons, one column needs to connect to
two pontoons. After considering various options, a hexagonal shape is proposed as the most suitable
design. To ensure that the stiffeners of the pontoons fit the stiffeners of the column perfectly, two of
the column sides are made to be the same width as the pontoon. Other sides are chosen to be integers
and dimensions are chosen so that the main column-to-side-column section area ratio is the same as
for circular columns.
Table 4.2 and Figure 4.3 provide information about the column sections.
Cylindrical columns Square columns
Pros
1. Loads are spread evenly without stress
concentrations.
2. Smaller wave impact and drag. [17]
1. Flat plates are easy to put and weld
together.
2. Column intersects with a pontoon at 90
degrees, making inner structure
arrangement easy.
Cons
1. Bending of plates adds time and cost to the
construction.
2. It’s difficult to connect column girders with
pontoon and bracings.
3. Increased sway and surge amplitudes [17]
1. Potential stress concentration points in
the corners.
2. Noticeably larger drag coefficient.
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Table 4.2 Section modulus and area of the columns.
Round Hex
Main column
Area, m
2
314.16 314.38
min Wx, m
3
785.4 802.05
min Wy, m
3
785.4 753.8
Side column
Area, m
2
153.94 158.30
min Wx, m
3
269.4 275.89
min Wy, m
3
269.4 238.85
Figure 4.3. Circular and hexagonal sections comparison. X-axis is in red, Y-axis is in blue.
Both tetrahedral (square section) and hexahedral columns share the simplicity of manufacturing
advantage. There is no equipment to make 14 m diameter pipes with one seam (at least in Taiwan),
so cylindrical and polyhedral columns are all fabricated by welding numerous steel plates together.
In the case of polyhedral columns, steel plates can be welded automatically into one wall-sections
while lying flat, and then the sections are easily assembled together to form a column. In the case of
cylindrical columns, every plate would have to be bent first, requiring equipment and processing
time; moreover, plates could not be assembled into sections while lying flat because of their
curvature, they would have to be placed vertically, supported by cranes, then welded manually or
semi-manually, taking not only much more time, equipment and workers to complete the assembly,
but also the quality of manual welding is inherently inferior to automatic welding; weld strength is
particularly important for deeply submerged structures. All this equally applies to the internal
stiffeners, which would also have to be bent and welded onto the shell. Finally, curved structures are
more difficult to store and transport. Thus, it is evident, that with the same steel weight, cylindrical
columns are definitely more expensive in manufacturing, thus the exact percentage of the cost
difference is subject to local shipyard procedures and equipment.
However, the easy-to-manufacture polyhedral shapes have another perceived weakness – stress
concentrations. To check for them, finite elements analysis was conducted with turbine weight and
gravity as loads. A stress concentration was indeed found in Fig. 4.4, but only in corners where the
bracing and pontoon connect to the column’s inner side, and its value of 262 MPa is acceptable for
the preliminary structure design stage. This corner can easily be reinforced during subsequent
design.
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Figure 4.4. Stress distribution in the main column top.
In Figure 4.5, the original TaidaFloat is shown along with two new hexagonal variants:
To determine the final shape, an international expert group consisting of twenty specialists from
the industry and academia were asked to vote. Interestingly, half of the votes went to the original
circular platform, and half went to the hexagonal platform concept.
Figure 4.5. Three candidates of floater designs for TaidaFloat (dimensions before the change for
manufacturing).
After careful consideration, the purple hexagonal shape was chosen – as this platform is
designed to be mass-manufactured, construction ease is more important than a slightly better wave
response. As this platform is made with flat plates and the pontoon is perpendicular to the column
side, it retains all the benefits of the square section column from table 1, at the same time the cons are
not as bad as for the full square shape, wave impact and drag are still less.
Following the principle of a close collaboration with the shipyard, the platform dimensions were
changed to fit the shipyard’s steel plate dimensions and welding equipment sizes; e.g. pontoon and
bracing height were reduced from 4 to 3.75 m to fit 3.8 m width steel plates produced by Taiwanese
steel mills.
After all the modifications, the latest version TaidaFloat characteristics are as in Table 4.3.
Table 4.3. TaidaFloat’s main characteristics.
TaidaFloat
Ver sio n 3
TaidaFloat
Ver sio n 4
Displacement (t) 23000 20300
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Hull weight (t) 4715 4000
Pontoon ballast (t) 13240 9829
Column ballast (t) 1850 3344
GM (trim/heel) (m) 21.6/ 26.2/
13.2 16.8
CG height (m) 16.62 17.35
Max. heel angle (°) 8.08 6.64
5. Bracing design
In addition to the sea-incurred loads, it is important to consider the loads that the wind turbine
will impose on the platform. During normal operation and even during typhoon conditions when
the turbine blades still receive wind loads, the turbine will generate a significant bending moment on
the supporting structure. This loading consists of three force components and three moment
components, with the most prominent being the fore-aft bending moment and the vertical force that
includes the weight of the turbine itself. Figure 5.1 shows the stress distribution in the platform,
which highlights the importance of the bracing, especially in the connection parts, as they experience
the highest stresses.
Figure 5.1. Stress distribution with 6 components wind load applied. Green area is higher stress due
to wind turbine moment.
As first described by Jonkman [18], the wind turbine installed on a FOWT can generate several
times the moment on its support that the same turbine would generate on land. Thus, it is essential
that the bracing is designed to withstand these loads to ensure the platform can fulfil its primary
purpose of supporting the turbine. Fatigue life is also significantly reduced under these loads, further
emphasizing the importance of robust bracing design. Future research will investigate the impact of
wind turbine moments on bracing in more detail, and this will be the subject of an upcoming paper.
Note that bracing can be structurally critical. The worst structural failure in a semi-submersible
may be the Alexander Kielland accident in 1980, which resulted in the capsizing of the floater [19].
The disaster started from a fatigue crack in bracing. The damaged bracing caused the column to break
off from the platform. Consequently, the semi-submersible capsized.
6. Discussion
In this section, we will discuss the findings of the study and highlight the key factors that need
to be considered when designing a floating offshore wind turbine (FOWT) platform.
The study analyzed 13 different platform configurations, under three (3) different design load
parameters (DLP). The objective was to identify the most cost-effective and structurally efficient
platform design that can withstand the environmental loads and stresses exerted on the FOWT
platform.
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Based on the analysis, platform E with a T-shaped pontoon provides the most cost-effective
solution under the assessed DLC and DLP. It is robust, relatively cheap, and easy to fabricate.
However, considering that FOWT floaters are a relatively new type of structure with a history of
failures, a safer platform configuration might be preferred for a new 15 MW platform. In this case,
the material economy is not as important as the safety of the platform. Platforms A and C, both ring
pontoons with full bracing, are considered the safest configurations. While they are structurally
similar, they may have different hydrodynamic performance and RAO, which requires further
investigation.
Additionally, it is important to consider the draft of the platform and its relation to the pontoon.
Typically, pontoons are permanently filled with water before exploitation to counteract outside water
pressure. However, in the case of a floating offshore wind turbine, the emptied pontoon provides
floatation during the transportation and installation stages. The internal structure of the pontoon
needs to be strong enough to support water pressure exceeding 200 kPa. However, the mass of all
this reinforcement helps bring the pontoon’s center of gravity further down, improving stability. It is
cheaper to add weight by increasing pontoon steel parts thickness than by pouring concrete inside
when considering added operational costs. The added buoyancy is crucial when entering and exiting
shallow ports, allowing platforms (Cases A-E) to be assembled and serviced closer to their
deployment area, while cases G-K are limited to very deep ports or have to use temporary floatation
modules.
Finally, the hexahedral column shape is chosen for TaidaFloat by the design team as it combines
the best attributes of cylindrical and square shapes. The ease of construction with flat steel plates
makes the square shape stand out.
One potential drawback of the hexahedral column shape chosen for TaidaFloat is that it may not
be as efficient in terms of space utilization compared to other shapes. Future research could explore
ways to optimize the design to maximize space utilization without compromising on other
performance metrics.
Another area for future research is the long-term durability, fatigue life and maintenance
requirements of these designs. As FOWT floaters are relatively new structures, there is still much to
learn about their long-term behavior and performance in real-world conditions. Continued
monitoring and research can help to identify any potential issues and optimize the design for
improved durability and longevity.
7. Conclusion
In conclusion, designing an efficient and cost-effective floating offshore wind turbine platform
requires consideration of various factors such as hydrodynamic performance, structural stability, and
operational costs. Based on the research in this study, the design team chose the following for
TaidaFloat:
• A hexahedral column, as it combines the best attributes of cylindrical and square shapes, and
uses flat steel plates making the construction much easier and faster.
• A full-ring pontoon configuration for low stresses and the ability to control draught by
ballasting.
• The ring bracing configuration in order to prevent stress concentrations and fatigue damage at
connection points and efficiently distribute the wind turbine’s force across the structure.
The findings of this study can provide valuable insights for future FOWT platform design and
development. Further research is necessary to investigate other potential platform shapes and
configurations and optimize their performance.
Acknowledgments: Anonimized.
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