Ship Handling in Adverse Weather

Question 1

Encounter wave period

Answer 1

The period of encounter TE could be either measured as the period of pitching by using stop watch or calculated by a formula.

Question 2

MSC 1228

Answer 2

Guidelines on turing circle, stopping distances and zig-zag test.

Question 3

Surf-riding and broaching-to

Answer 3

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.

Question 4

Synchronized rolling

Answer 4

Large rolling motions may be excited when the natural rolling period of a ship coincides with the encounter wave period. In case of navigation in following and quartering seas this may happen when the transverse stability of the ship is marginal and therefore the natural roll period becomes longer.

T=0.8 B/^GM

T = Natural Roll Period
B = Beam
GM= Metacentric Height

Question 5

Parametric rolling

Answer 5

Parametric rolling occurs when the pitching period is either equal to or half of that of the rolling period.

Question 6

Dangerous zone

Answer 6

The dangerous zone indicated in figure 3 corresponds to such conditions for which the encounter wave period (TE) is nearly equal to double (i.e., about 1.8-3.0 times) of the wave period (TW).