A ship 100m long, and with a displacement of 2200 tonnes, has longi tudinal metacentric height 150m. The present drafts are 5.2m F and 5.3m A. Centre of flotation is 3m aft of amidships. Find the new drafts if a weight of 5 tonnes already on board is shifted aft through a distance of 60 metres.

A ship 100m long, and with a displacement of 2200 tonnes, has longi tudinal metacentric height 150m. The present drafts are 5.2m F and 5.3m A. Centre of flotation is 3m aft of amidships. Find the new drafts if a weight of 5 tonnes already on board is shifted aft through a distance of 60 metres.

Reference: Ship Stability for Masters & Mates (6^th edition), Exercise – 16.3

 

Solution:

MCTC = w*GM_L/100L

            = 2200*150/100*100

            = 33 ton-m/cm

Change in trim = w*d/MCTC

                         = 5*60/33

                         = 9.09 cm

x/t = l/L

=> x/9.09 = 47/100

=> x = 4.27 cm

 

y/t = L-l/L

=> y/9.09 = 100-47/100

=> y = 4.82 cm

 

New draft AFT = 5.3 + 4.27/100 = 5.342 m

New draft FOR = 5.2 – 4.82/100 = 5.152 m