Page 11 - IJOCTA-15-2

M. Perala, S. Chandrasekaran, E. Begovic / IJOCTA, Vol.15, No.2, pp.202-214 (2025)
Table 1. Geometric parameters

Design particular Notation Magnitude Unit
Length overall (m) LOA 231.50 m
Length between perpendiculars LBP 210.0 m
Design beam B 36.0 m
Design draft or operating draft Deep 11.5 m
Lightship draft Tight 8.5 m
Molded depth D mld 17.8 m
Displacement ∆ 50,579 tonnes
Displaced volume ∇ 49,349 m 3
Length on waterline L WL 223.47 m
Beam on waterline B WL 31.68 m
Position of moonpool from transom P 103.35 m
Moonpool length L 24.8 m
Moonpool breadth B 12.8 m
Cutout slant angle α 90 ◦
Waterplane area A WP 5,959.6 m 2
Wetted surface area A wetted 10,026 m 2
Longitudinal CoG X G 105 m
Transverse CoG Y G 0 m
Vertical CoG Z G 15.13 m
Radius of gyration about X K XX 12.6 m
Radius of gyration about Y K yy 104.175 m
Radius of gyration about Z K ZZ 104.175 m
Abbreviation: CoG: Center of gravity.

and represented by the JONSWAP spectrum, 15
featuring a peakedness parameter of 3.3. The ex-
ample plot (Figure 6) shows the JONSWAP spec-
trum for an irregular wave with a height of 5 m
and a period of 10 s. The JONSWAP spectrum
was selected for this analysis as it accounts for
the energy imbalance in waves, typical of seas
that are not fully developed. It makes the JON-
SWAP spectrum especially suitable for simulating
realistic offshore conditions. By incorporating the
JONSWAP spectrum, the study ensures that the
wave conditions closely mimic irregular sea states,
creating a robust testing environment to evaluate
the AI algorithm’s performance.
Figure 4. Wave directions
Abbreviation: SB: Starboard

This approach guarantees a thorough and re-
alistic analysis of the drillship’s dynamic perfor-
mance across these wave conditions, providing
the foundational data needed to implement the
AI-driven station-keeping control system. Figure
5 depicts the numerical model of the drillship,
clearly illustrating the position of CoG. The fol-
lowing wave parameters are used for testing the
AI algorithm, with the sea states being irregular Figure 5. Numerical model
206