Ship Trim
1. Statement of the problem: A ship of length $L = 110\text{ m}$ floats on an even keel with draft $4.85\text{ m}$ and its LCF is $1.0\text{ m}$ forward of amidships.
2. A load of $30\text{ t}$ is moved forward until the forward draft becomes $5.05\text{ m}$.
3. Find the distance the weight was moved given $\text{MCT}_{1\text{ cm}} = 64\text{ t-m}$.
1. Compute the change in forward draft.
The forward draft increases from $4.85\text{ m}$ to $5.05\text{ m}$, so
$$\Delta T_f = 5.05 - 4.85 = 0.20\text{ m} = 20\text{ cm}$$
2. Find the distance from the LCF to the forward perpendicular.
Half the ship length is $L/2 = 55\text{ m}$, so the distance from the LCF (1.0 m forward of amidships) to the forward perpendicular is
$$d_f = 55 - 1.0 = 54\text{ m}$$
3. Relate the change in forward draft to the change in trim.
Trimming about the LCF gives the relation
$$\Delta T_f = \Delta T\cdot\dfrac{d_f}{L}$$
where $\Delta T$ is the total change in trim (forward draft minus aft draft).
4. Solve for the change in trim $\Delta T$.
$$\Delta T = \Delta T_f\cdot\dfrac{L}{d_f}$$
Substituting numbers,
$$\Delta T = 0.20\times\dfrac{110}{54} = 0.407407\text{ m} = 40.7407\text{ cm}$$
5. Compute the trimming moment required.
Moment to change trim is $M = \text{MCT}_{1\text{ cm}}\times \Delta T(\text{cm})$, so
$$M = 64\times 40.7407 = 2607.111\text{ t-m}$$
6. Relate the trimming moment to the moved weight and solve for distance.
Moving weight $w=30\text{ t}$ a distance $x$ produces a trimming moment $w\,x$, so
$$x = \dfrac{M}{w}$$
Thus
$$x = \dfrac{2607.111}{30} = 86.9037\text{ m}$$
7. Final answer.
Therefore the weight was moved approximately $86.9\text{ m}$ forward.