The weather criterion is one of stability criteria to verify ability of a ships to withstand the combined effects of severe wind and rolling criteria in dead ship condition. An overestimated roll angle is obtained when the weather criterion is applied to ships with breadth and draught ratios larger than 3.50 and ratios between vertical centre of gravity and draught larger than 1.50. This paper discusses the assessment of weather criterion for an Indonesian ro-ro ferry by model experiments. The drift test is performed in four wave steepnesses with wave frequencies near the roll natural frequency. The maximum roll amplitude is used to calculate the effective wave slope coefficient corresponding to the wave steepness, with Bertin’s coefficient obtained by the roll decay test. The damping factors correspond to the breadth and draught ratio as well as the bilge keel contribution are determined using the formula of weather criterion with the roll angle obtained by the Japanese formula with a correction factor of 0.70 due to the irregularity of waves. The obtained effective wave slope coefficient and the damping factors due to breadth and draught ratio and the bilge keel are smaller than those used in the weather criterion.
The weather criterion is one of stability criteria to verify ability of a ships to withstand the combined effects of severe wind and rolling criteria in dead ship condition. An overestimated roll angle is obtained when the weather criterion is applied to ships with breadth and draught ratios larger than 3.50 and ratios between vertical centre of gravity and draught larger than 1.50. This paper discusses the assessment of weather criterion for an Indonesian ro-ro ferry by model experiments. The drift test is performed in four wave steepnesses with wave frequencies near the roll natural frequency. The maximum roll amplitude is used to calculate the effective wave slope coefficient correponding to the wave steepness, with Bertin’s coefficient obtained by the roll decay test. The damping factors correspond to the breadth and draught ratio as well as the bilge keel contribution are determined using the formula of weather criterion with the roll angle obtained by the Japanese formula with a correction factor of 0.70 due to the irregularity of waves. The obtained effective wave slope coefficient and the damping factors due to breadth and draught ratio and the bilge keel are smaller than those used in the weather criterion.
Masyarakat pesisir Jeneponto melakukan usaha budidaya rumput laut secara berkelompok maupun perseorangan. Salah satu kelompok pebudidaya rumput laut di Lingkungan Pattontongan Kecamatan Binamu yaitu Kelompok Pattotongan City. Sarana produksi yang digunakan dalam budidaya rumput laut antara lain perahu. Umumnya perahu fiberglass masih didapatkan dari bantuan atau hibah pemerintah, jarang sekali yang membeli langsung karena terkendala biaya. Sehingga perlu ada upaya untuk dapat menekan biaya perolehan perahu yaitu pebudidaya membuat sendiri perahu. Pada bulan September dan Oktober tahun 2016, melalui program Ipteks Bagi Masyarakat (IBM) Universitas Hasanuddin dilakukan bimbingan dan pelatihan reparasi perahu fiberglass kepada kelompok pembudidaya dengan hasil budidaya mampu mengenal bahan dan peralatan reparasi fiberglass dan teknik-teknik mereparasi lambung perahu. Kemampuan ini belum cukup untuk dapat membuat perahu, maka diperlukan sebuah kegiatan berupa pengayaan keterampilan dalam pembuatan perahu. Hasil yang diperoleh melalui pengayaan keterampilan ini adalah peserta mampu (1) membaca gambar desain perahu. (2) memidahkan desain perahu ke skala penuh (3) membuat cetakan perahu (4) melaminasi perahu atau mampu menerapkan metode hand lay-up dengan baik dan tepat. Manfaat yang dapat diperoleh dengan keterampilan yang dimiliki peserta adalah mampu membuat sendiri perahu sehingga dapat menghemat biaya modal. Lebih dari itu, dapat membuka lapangan kerja yang bermuara pada peningkatan kesejahteraan pebudidaya.
Wave is one of the natural phenomena that gives effect to the cruise ship. The energy produced by the wave is very large that makes the ship turn directions. Therefore the turn has an error coordinates of the starting point of a ship. Deviation of the coordinates has made a further distance and increase fuel consumption, so the operational costs being higher. The research would predict the drift angle, the ship speed and rudder angle to be used after the ship got the influence of wave by taking into account the motion of surge, sway, yaw. Simulations are performed by using Delphi software, with variations of the wind height of 0.5 m, 1 m, 1.5 m, and 2 m, the wave flatness of 0.01, the speed of the wind of 0 and 10 m/s and incoming wave direction 0° - 180° on the side of the ship. It is obtained that the biggest of drift angle happened on 50° wave direction. The biggest of rudder angle happened on 110° wave direction while that fastest ship speed happened on 160° wave direction.
Nowadays, the container transportation service increases rapidly and then this condition emphasizes the container ship growth. The containers stowage only on deck can cause a serious problem subjected to ship stability. The objective of present study is to analyze the stability of a container ship due to containers stowage on deck. Also, twelve cases based on weight conditions C1 to C2 were simulated in order to distinguish the impact of the weight on stability parameters KG, GZ, vanishing stability angle, and stability range. The results show the weight condition affects on the magnitude of KG and LCG wherein the position of centre of gravity point is behind amidship and the decrease of LCG due to the decrease of consumable weight ≥ 50% is average 2.06%. The effect of the decrease of consumable weight ≥ 50% can make stern trim condition (C3, C5, C6, C8, C9, C11, and C12). The containers stowage on deck impacts on reducing the KG as well the magnitude GZ becomes small. In addition, the vanishing stability and stability range become small. Nevertheless, the stability parameters due to the containers stowage on deck fulfil the requirement of Intact Stability Code. Overall KG values due to the weight condition (C1 to C12) are significantly lower than the limiting KG. This means that overall KG due to weight conditions fulfill the stability criterion.
Prediction of ship performance in preliminary ship design is an important consideration. It could guarantee ship in safe and comfort. However, many design works did not involve simultaneously ship performances predictions in preliminary design. Moreover, ship designers sometimes modified a ship form to obtain proper design without ship performance consideration. Therefore, this study concerns on predictions of total resistance and added wave resistance of a ferry using a hybrid particle-grid method and then its motions response after modifying bow and stern parts by conducting experiment. Research results show total resistance and added wave resistance have a significant different, therefore, it would be an important consideration in determining ship powering in preliminary ship design. The non-dimensional added wave resistance increases in increasing wave length from /L pp = 0.5 to 1.0 and it decreases after L/= 1.0. In addition, it tends to decrease caused by increasing ship speed. The comparison of averaged heave and pitch amplitudes between basic forms after modifying bow and stern parts is quiet similar. However, the rolling amplitude of the modified form is significantly higher comparing with the basic form. We conclude that a ship could be design in preliminary design take into account performances predictions by using numerical method and experimental work.
A towed barge is one of the typical sea transportation systems that is basically composed of towing and towed ships connected to each other by a tow rope. During a towing operation exposed to rough sea condition, the risk of collision and breakage of a tow rope may be high and the consequences serious. This paper describes an experimental investigation of a towed barge’s motions in heading waves. The effects of various lengths and the configuration of tow ropes incorporated with various loading conditions of the towed barge have been taken into account. Here, three tow-rope lengths were used, namely 1L, 1.5L, and 2L; meanwhile, the two tow-rope configurations i.e., Straight-Tow (ST) and V-Tow (VT) models were applied and incorporated with 50% and 100% of the loading conditions of the towed barge. Regardless of the tow-rope models of ST and VT, the results revealed that the towed barge’s motion responses were generally proportional to the increase of the towline lengths and the towed barge’s loading conditions. It should be noted here that the VT model with 1L tow rope length in the full loaded condition has less RAO of her heave and pitch motions as compared to the other towing arrangements. Merely, this research investigation provides very useful guidance on a ship towing navigation in waves.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.