Hydrographic surveying tools: what is a station pointer primarily used for during charting operations?

Introduction / Context:
Hydrographic surveys determine depths (soundings) and positions to produce nautical charts. A station pointer is a classical plotting instrument used alongside three-point or two-point resection to transfer observed angles onto the chart.

Given Data / Assumptions:

• Observer measures horizontal angles from a boat to known shore points.
• Known control points (triangulation points) are already plotted on the chart.
• Goal is to plot the boat's position and attach the measured depth (sounding).

Concept / Approach:
The station pointer has three arms set to the measured angles. By placing and rotating it over the chart so that the arms pass through the respective control points, the instrument's center directly marks the boat's position, enabling accurate plotting of the sounding.

Step-by-Step Solution:
Measure shore angles to known marks.Set station pointer arms to the observed angles.Place on chart; rotate until arms pass through the three plotted shore points.Mark center point; annotate measured depth → plotted sounding.

Verification / Alternative check:
Textbook hydrography workflows list station pointers explicitly for plotting positions from angular fixes.

Why Other Options Are Wrong:

• Making soundings: done with echo sounders/lead lines, not station pointer.
• Marking hazards: a charting outcome, not the instrument's core function.
• Tidal observations: performed with tide gauges or staffs.

Common Pitfalls:

• Confusing data acquisition (sounding) with position plotting on charts.

Final Answer:
For plotting of soundings in harbour area