The virtual loss of GM after taking the blocks overall

When a ship takes the blocks overall, the water level will then fall uniformly about the ship, and for each centimetre fallen by the water level P will be increased by a number of tonnes equal to the TPC. Also, the force P at any time during the operation will be equal to the difference between the weight of the ship and the weight of water she is displacing at that time.

Example 4

A ship of 5000 tonnes displacement enters a drydock on an even keel. KM = 6 m. KG = 5.5 m, and TPC = 50 tonnes. Find the virtual loss of metacentric height after the ship has taken the blocks and the water has fallen another 0.24 m.

P = TPC X reduction in draft in cm

50 24

P 1200 tonnes

254 Ship Stability for Masters and Mates Method (a)

Virtual loss(MMj)

+1 0

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