Question 63 FCP01 - First Class Pilot

The Correct Answer is D ### Explanation of Why Option D ("311°pgc") is Correct To determine the required Gyro Course ($\text{C}_{\text{g}}$) to steer, we must start with the True Course ($\text{C}_{\text{t}}$) desired, apply the allowance for leeway, and finally apply the gyrocompass error. **1. Determine the Course to Steer (CTS) to account for Leeway:** The desired True Course Over Ground ($\text{C}_{\text{t}}$) is $312^{\circ}$. Leeway is the angle the vessel is drifted by the wind. The wind is West by South, meaning the wind is coming from the SW quadrant, pushing the vessel generally Northeast. * **Wind Direction:** West by South (WbS, approximately $258.75^{\circ}$ True, or coming from the SW). * **Vessel Drift Direction:** The wind pushes the vessel to leeward (Northeast direction). * **True Course of Vessel (Heading):** Since the vessel is being pushed to the right (Northeast) of the intended track, the vessel must be steered further *into the wind* (to the left/westward) to stay on the desired track. $$\text{C}_{\text{h}} = \text{C}_{\text{t}} \pm \text{Leeway}$$ We must steer $4^{\circ}$ further to the left (Westward/lower numerical value) to counteract the $4^{\circ}$ drift to the right (Eastward). $$\text{Course to Steer True (C}_{\text{t}}) = 312^{\circ} - 4^{\circ} = 308^{\circ} \text{T}$$ **2. Determine the Gyro Course (Cg) to steer:** We now need to convert the True Course to Steer ($\text{C}_{\text{t}} = 308^{\circ}$) into the corresponding Gyro Course ($\text{C}_{\text{g}}$) using the Gyro Error (GE). The conversion relationship is: $$\text{True Course} = \text{Gyro Course} + \text{Gyro Error (E/W)}$$ The error is $3^{\circ}$ West ($3^{\circ}\text{W}$). "West" means the Gyro reading is **W**rongly **L**ow (WLE), or that the True course is higher than the Gyro course. Therefore, the Gyro Error is negative when converting $\text{C}_{\text{g}}$ to $\text{C}_{\text{t}}$. $$\text{GE} = -3^{\circ}$$ $$308^{\circ}\text{T} = \text{C}_{\text{g}} + (-3^{\circ})$$ $$\text{C}_{\text{g}} = 308^{\circ} + 3^{\circ}$$ $$\text{C}_{\text{g}} = 311^{\circ}\text{pgc}$$ The required gyro course is $311^{\circ}\text{pgc}$. *** ### Explanation of Why Other Options Are Incorrect **A) 315°pgc** This result is obtained by incorrectly *adding* both the leeway and the gyro error to the true course ($312^{\circ} + 4^{\circ} + (-3^{\circ})$ or $312^{\circ} + 4^{\circ} + 3^{\circ}$, depending on the sign handling). This fails to correct for the wind drift (leeway) by steering into the wind and misapplies the gyro error correction. **B) 305°pgc** This result is obtained by incorrectly subtracting both the leeway and the gyro error ($312^{\circ} - 4^{\circ} - 3^{\circ} = 305^{\circ}$). While the leeway correction is applied correctly (steering into the wind), the gyro error is applied backward. If the gyro error is $3^{\circ}\text{W}$, the required Gyro Course must be *higher* than the True Course (by $3^{\circ}$). **C) 318°pgc** This result is obtained by incorrectly applying the leeway correction (steering away from the wind) and applying the gyro error incorrectly or backward: * $312^{\circ}\text{T}$ (Track) * $312^{\circ} + 4^{\circ} = 316^{\circ}\text{T}$ (Incorrectly steering away from WbS wind) * $316^{\circ} + 2^{\circ}$ (Mixing up GE, e.g., $3^{\circ}E$ instead of $3^{\circ}W$). * If we incorrectly steer away from the wind and apply $3^{\circ}\text{E}$ error: $312^{\circ} + 4^{\circ} - 3^{\circ} = 313^{\circ}$. * $318^{\circ}$ results from incorrectly adding both corrections: $312^{\circ} + 4^{\circ} + 2^{\circ}$ (or similar arithmetic error).