Question:

A ship of length 100 m and displacement 5000 tonne floats even-keel at 6.5 m in fresh water of density 1000 kg/m\(^3\). The ship’s hydrostatic properties are:
MCT per cm is 10 tonne-m, TPC in seawater is 6.25,
LCB is 2 m forward of amidship,
LCF is 2 m forward of amidship.

The ship has moved to seawater of density 1025 kg/m\(^3\) without change in the displacement. The new forward and aft draughts are ________ respectively.

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When LCB = LCF and no external moments act, even keel is maintained even after density changes.
Updated On: Apr 25, 2025
  • 6.04 m and 6.54 m
  • 6.30 m and 6.64 m
  • 6.64 m and 6.30 m
  • 6.30 m and 6.30 m
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The Correct Option is D

Solution and Explanation

Step 1: Find change in mean draught due to higher density seawater \[ \Delta T = \frac{(1000 - 1025)}{1025} \times \frac{5000}{6.25} \approx -0.2\, {m} \] Step 2: New mean draught \[ T_{{new}} = 6.5 - 0.2 = 6.3\, {m} \] Step 3: Check for trim change due to LCB and LCF both being 2 m forward of amidship \[ {LCB} = {LCF} \Rightarrow {no trimming moment} \] Step 4: Therefore, trim remains even-keel \[ {Forward draught} = {Aft draught} = 6.30\, {m} \] Conclusion: Forward and aft draughts both equal 6.30 m
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