3.1 Phenomena occurring in following and quartering seas
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Statutory Documents - IMO Publications and Documents - Circulars - Maritime Safety Committee - MSC.1/Circular.1228 – Revised Guidance to the Master for Avoiding Dangerous Situations in Adverse Weather and Sea Conditions – (11 January 2007) - Annex - Revised Guidance to the Master for Avoiding Dangerous Situations in Adverse Weather and Sea Conditions - 3 Dangerous Phenomena - 3.1 Phenomena occurring in following and quartering seas

3.1 Phenomena occurring in following and quartering seas

 A ship sailing in following or stern quartering seas encounters the waves with a longer period than in beam, head or bow waves, and principal dangers caused in such situation are as follows:

Parent topic: 3 Dangerous Phenomena

3.1.1 Surf-riding and broaching-to

 When a ship is situated on the steep forefront of a high wave in following or quartering sea conditions, the ship can be accelerated to ride on the wave. This is known as surf-riding. In this situation the so-called broaching-to phenomenon may occur, which endangers the ship to capsizing as a result of a sudden change of the ship's heading and unexpected large heeling.

3.1.2 Reduction of intact stability when riding a wave crest amidships

 When a ship is riding on the wave crest, the intact stability can be decreased substantially according to changes of the submerged hull form. This stability reduction may become critical for wave lengths within the range of 0.6 L up to 2.3 L, where L is the ship's length in metres. Within this range the amount of stability reduction is nearly proportional to the wave height. This situation is particularly dangerous in following and quartering seas, because the duration of riding on the wave crest, which corresponds to the time interval of reduced stability, becomes longer.

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