Motions Analysis of a Phinisi Ship Hull with New Strip Method

Phinisi is the name of a renowned traditional wooden ship from South Sulawesi, Indonesia. The ship has been proven to be tough and reliable in sailing even to this very day. However, the ship is built only with a very traditional method and simple tools. There is no hydrodynamic analysis performed prior to the building of the ship. Therefore, in order to analyze the performance of the ship motion of a Phinisi ship hull, New Strip Method (NSM) is employed in the present study. With NSM, the ship hull is divided into several strips and the hydrodynamics forces are computed on each strip. Moreover, because the ship is assumed to be slender, the total forces are obtained by integrating the force on each strip. From the computation results, it can be shown that the resonant frequency of the analyzed Phinisi hull is shifted to lower frequency as the ship speed increases

SEAKEEPING PREDICTION OF DEEP-V HIGH SPEED CATAMARAN USING COMPUTATIONAL FLUID DYNAMICS APPROACH

Seakeeping is the dynamic response of the ship in waves that may affect to passenger’s uncomfortability due to a harsh environmental condition.  Therefore, an extensive assessment of seakeeping performance in the initial step of ship design is necessarily required. The authors here proposed to analyze the seakeeping performance of ‘deep-V’ high speed catamaran using Computational Fluid Dynamics (CFD) approach. Several effects of Froude number (Fr), wave-length

COMPUTATIONAL PREDICTION OF A PROPELLER PERFORMANCE IN OPEN WATER CONDITION

n presence of hydrodynamics phenomena occur surrounding propeller evidently affects on accuracy’s prediction of thrust, torque and its efficiency. To achieve the objective, a Computational Fluid Dynamics (CFD) simulations approach is then proposed to obtain a reliable prediction of the thrust (KT), torque (KQ) and efficiency (η) coefficients in open water condition. The effect of various blade numbers associated with constant propeller revolution (RPM=1320) and pitch ratio (P/D=1.0); are performed within the range of advance ratio from 0.1J1.0. The results revealed that the increase of blade number from Z=3 to 5 was proportional with the increase of thrust (KT) and torque (KQ) coefficients; meanwhile, it was reduced the maximum efficiency (η) that possibly lead to downgrade the propeller performance. It should be noted here, the propeller with three blade numbers (Z=3) provide the highest efficiency (η) up to 78.8% at J=0.9. These CFD simulation results are very useful as a preliminary study of propeller characteristics

A fundamental CFD investigation of offshore structures for artificial coral reef development

Rigs-to-Reefs (R2R) is an alternative for oil and gas industry for decommissioning purpose. The program will benefit marine life as an artificial reef for a sustainable solution to promote ecosystem growth. For any oil platform considered for reefing, an extensive study on the suitability and performance of the artificial reef is essential. These studies will evaluate the stability and relevance of the structure as an artificial reef when deployed on the seabed. This paper presents the research on dynamic response and flow characteristics of a conceptual proposed R2R platform. The Computational Fluid Dynamics (CFD) simulation is intended to study the dynamic responses and flow characteristics analysis of a jacket oil platform for optimal settlement and growth of corals. Artificial reef performances were evaluated by calculating the performance indices of the upwelling and back eddy profile. It was found that the upwelling efficiency index is higher at current direction normal to the platform due to the higher frontal area exposed to the incoming flow. Meanwhile, back eddy efficiency index shows a significant low value for all directions. The CFD results presented will be discussed in terms of the possibility of better performance of an artificial reef which considering engineering and biological aspects

Analysis of an asymmetrical bridle towline model to stabilise towing performance of a towed ship

This paper addresses an asymmetrical bridle towline model as a feasible solution model to stabilize towing performance of a towed ship. The basic thinking behind the approach adopted, is to deal with a better towing stability than employing the typical towline model1. Several towing parameters which may affect a towed ship motion behaviour i.e., tow angle and tow point position, are investigated theoretically. The nonlinear numerical time-domain simulation showed that the increase of towing angle up to 30 degrees and shifting tow point from 0.5 to 0.8 resulted in remarkable reduction in slewing motion of the unstable towed ship and the towline tension, which enhances effectively her towing stability

Investigation of the corrosion factor to the global strength of aging offshore jacket platforms under different marine zones

This paper investigates the corrosion factor to the global strength of aging offshore jacket platforms in different marine zones. The time-dependent corrosion wastage model from Melchers, an active corrosion expert, by considering different marine zones, i.e., atmospheric, splash, and immersion. In addition, three aged jacket platform models of the originally installed platform were selected to investigate the effect of corrosion wastage on global strength. The jacket platform's global strength is calculated by the Reserve Strength Ratio (RSR) value. RSR is obtained via nonlinear static pushover analysis and is always used to estimate overall structure strength reserves. Safety assessment is evaluated by the PETRONAS Technical Standard (PTS). According to this study, immersion zone corrosion is the most influential zone after splash zone corrosion. Furthermore, the study also predicts the lifetime of each jacket platform, and it is useful for structural engineers to estimate corrosion allowance at the early design stage

The influence of ramp shape parameters on performance of overtopping breakwater for energy conversion

10.3390/jmse8110875Journal of Marine Science and Engineering8111-1