In hydrographic surveying, when locating soundings by the “one range and one angle” method from the shore, which sequence of operations correctly describes the field procedure (establishing control, fixing key soundings, and filling in intermediate points)?

Introduction / Context:
Hydrographic surveying requires reliable methods to position soundings (depth measurements) relative to the shoreline. The “one range and one angle” method is a classic approach when full electronic positioning is unavailable. It combines linear guidance (a shore range) with angular fixes at intervals to maintain positional accuracy while keeping the survey efficient.

Given Data / Assumptions:

• A clearly visible range line is set on the shore to guide the survey boat's track.
• Shore observers can read angles to the boat using a theodolite or sextant.
• Timing on the boat is steady to space intermediate soundings.

Concept / Approach:
The method blends geometric control with practical time-based spacing. The range line keeps the boat on a known alignment, reducing transverse positioning error. Angular fixes at the start, end, and at every tenth sounding “tie down” the run, while intermediate points use equal time spacing at near-constant speed, which is later adjusted against the angular control points.

Step-by-Step Solution:
Establish the range: align two shore marks to create a visible straight line for the boat to follow.Fix control soundings: determine exact positions of the first, last, and periodic (e.g., every tenth) soundings by angular observations from shore.Fill the gaps: acquire intermediate soundings at equal time intervals as the boat proceeds steadily on the range.Thus, the correct comprehensive description is “All the above.”

Verification / Alternative check:
Field manuals describe this combined approach to minimize cumulative position error: the range constrains lateral deviation while periodic angular fixes correct for speed fluctuations.

Why Other Options Are Wrong:

• Single elements (only range or only angles) are incomplete and risk drift in position.
• Omitting time-spaced intermediates makes the operation inefficient or too sparse.

Common Pitfalls:
Irregular boat speed invalidates time-spacing; poor range visibility or misidentified marks can cause systematic errors; insufficient angular control leads to position creep.

Final Answer:
All the above.