Exam Question
When a ship moves into water of different density, there will a change in its draught and trim. List out the minimum information required to calculate the final draughts. Also briefly outline the procedure involved. (16)
Class 2 (2nd Engineer)
SC&S
📅 Jul 2018
Reference Answer
If the specific gravity of the water in which the ship is floating changes without any changes to the ship's displacement, the ship's draft will change. The draft will change because the ship must displace the same mass of water, which no longer has the same density.
$$\Delta=V\times\rho$$
If the displacement ( Δ ) remains constant and the density ( ρ ) changes, the underwater volume must change; therefore, the ship's draft will change automatically.
If a ship goes from fresh water to salt water, buoyancy will increase and the draft will decrease. Inversely, a ship that goes from salt water to fresh water will see its draft increase.
$$\Delta=V\times\rho$$
If the displacement ( Δ ) remains constant and the density ( ρ ) changes, the underwater volume must change; therefore, the ship's draft will change automatically.
If a ship goes from fresh water to salt water, buoyancy will increase and the draft will decrease. Inversely, a ship that goes from salt water to fresh water will see its draft increase.
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