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.
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.
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.
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.
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