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Q1) A RO-RO ferry of length 120 m has a displacement of 12800 tonne in sea water of density 1025 kg/m³ with BM = 4.6 m.

The breadth of the ship at the waterline, between sections 3 and 7 is constant at 20 m.

To increase stability, sponsons, 2.7 m deep and of constant plan area to be fitted as shown in Fig Q1. For the new condition there is no change in draught and the load waterline is at mid-depth of the sponson.

The sponsons extend over the midship length between Sections 3 and 7, with sponson widths as shown in Table Q1.

Table Q1

Calculate the increase in BM due to the sponsons. (16)