Day 86: Specialized Applications – Wreck Search & Port Surveys | Masterpiece Edition | River Warrior

🔍 DAY 86: SPECIALIZED APPLICATIONS – WRECK SEARCH & PORT SURVEYS

⏱️ Estimated Reading Time: 15 Minutes | 🎓 Level: Professional Hydrographer / Survey Specialist

Finding the Lost and Mapping the Busy – Wreck Detection, Port Infrastructure, and Berth Clearance

Instructor: Engr. Rokib Hossain | River Warrior Academy

🏠 Course Homepage

📖 Table of Contents (Serialised)

Why Specialized Applications Set You Apart
Wreck Search & Investigation: Strategies and Sensors
Case Study: Bay of Bengal WWII Wreck Discovery
Port & Harbour Surveys: Berth Scanning, Channel Monitoring, Infrastructure
Interactive Wreck & Berth Clearance Simulator
Berth Scanning (Under‑keel Clearance, Sidescan for Quay Walls)
Navigation Channel Monitoring (Repeated Surveys, Shoaling Prediction)
Infrastructure Inspection (Piers, Dolphins, Subsea Pipelines)
Specialized Surveys Checklist
Resources & Software
Frequently Asked Questions (with internal links)
Action Items & Next Steps

1. Why Specialized Applications Set You Apart

General bathymetry is routine. Wreck search, port infrastructure surveys, and berth clearance require tailored techniques and integrated sensor use. Mastering these specialized applications makes you a sought‑after expert. You will learn to:

✅ Locate and characterize wrecks using MBES, side scan, and magnetometer.
✅ Conduct berth scanning for under‑keel clearance and quay wall inspection.
✅ Monitor navigation channels for shoaling and plan dredging.
✅ Inspect subsea infrastructure (pipelines, dolphins, piles) for integrity.

🧠 Golden Rule: For wreck search, never rely on a single sensor. Combine MBES (bathymetry), side scan (imagery), and magnetometer (ferrous detection) for positive identification.

🌊 River Warrior Pro-Tip: Port Survey Efficiency

In a busy port, time is money. Plan surveys during slack tide, use a fast‑launch MBES, and pre‑plot lines to avoid vessel traffic. A 4‑hour window can cover an entire berth.

2. Wreck Search & Investigation: Strategies and Sensors

Wrecks pose navigation hazards and can be environmental risks. A systematic search strategy:

Phase 1 – Desktop study: Historical charts, accident reports, local knowledge.
Phase 2 – Wide‑area reconnaissance: Use side scan sonar with 100‑200 m range per side. Line spacing equal to range.
Phase 3 – Targeted investigation: MBES for 3D model, magnetometer for ferrous mass estimation, ROV for visual confirmation.

3. Case Study: Bay of Bengal WWII Wreck Discovery (2025)

Objective: Locate a reported 50 m long steel wreck from wartime.

Desktop: Reviewed old admiralty charts and fisherman reports.
Side scan: 450 kHz, line spacing 100 m. Detected a 55 m long high‑intensity target with a clear 40 m shadow.
MBES: 400 kHz, produced a 3D model showing a broken hull, maximum height 6 m above seabed.
Magnetometer: 2000 nT anomaly, confirming ferrous mass.
ROV: Confirmed wreck identity, measured clearance for navigation.

🌊 The wreck was marked on the chart, and a 200 m exclusion zone was established – preventing a potential grounding.

4. Port & Harbour Surveys: Berth Scanning, Channel Monitoring, Infrastructure

Port authorities require regular surveys for:

Berth pockets – ensure depth tolerance for vessels.
Turning basins – no shoaling.
Approach channels – maintain design depth.
Quay walls – verticality, toe scour.
Dolphins and mooring piles – position and tilt.

📌 Typically, IHO Order 1a or Special Order (0.15 m depth tolerance) is required for berths.

📏 Wreck & Berth Clearance Simulator

Calculate required clearance for a wreck or berth pocket:

Object height above seabed (m): Vessel draft (m): Allowable under‑keel clearance (m): Survey depth at object location (m):

Clearance = 1.0 m – exceeds UKC requirement? No – require dredging or wreck removal.

5. Berth Scanning (Under‑keel Clearance, Sidescan for Quay Walls)

Under‑keel clearance (UKC) surveys: MBES with 0.2‑0.5 m grid. Use real‑time tide correction.
Quay wall inspection: Side scan sonar run parallel to wall, 5‑10 m offset, to detect scour holes and displaced blocks.
Berth pocket volume: Pre‑ and post‑dredge comparisons (grid method).

🚢 For container terminals, survey during low traffic hours (e.g., 02:00‑06:00) using a small survey boat. Pre‑plot lines to avoid moored vessels.

6. Navigation Channel Monitoring (Repeated Surveys, Shoaling Prediction)

Channels shoal dynamically. A monitoring programme:

Quarterly MBES surveys (or monthly for high‑silting areas).
Difference surfaces (current vs design) to identify critical shoals.
Shoaling rate (m/month) prediction using time series (Day 34).
Trigger for dredging when depth < design + 0.3 m safety margin.

📊 Use a colour‑coded “navigation risk map” for the client – green = safe, yellow = caution, red = urgent dredging.

7. Infrastructure Inspection (Piers, Dolphins, Subsea Pipelines)

Piers and dolphins: MBES for scour around piles, ROV for visual inspection of coatings.
Subsea pipelines: Side scan to detect free spans, magnetometer for ferrous pipes, ROV for cathodic protection.
Outfalls and intakes: MBES to confirm cover levels, side scan to detect debris.

💡 For pipelines, use a pipeline‑tracking ROV with a “cathodic protection probe” to measure coating condition.

8. Specialized Surveys Checklist

Desktop study completed (historical charts, accident reports).
Side scan line spacing ≤ 0.5 × range for wreck search.
MBES grid resolution ≤ 0.5 m for berth surveys.
Magnetometer deployed for ferrous detection (wrecks, pipelines).
ROV available for visual confirmation (if required).
Tide correction applied (real‑time or post‑processed).
All infrastructure features (piles, dolphins, walls) surveyed.
Difference surface computed (current vs design) for channel.
Report includes UKC calculation and hazard map.
Data archived with metadata for repeat surveys.

Click items to track progress (saved in browser).

9. Resources & Software

Software / ToolApplicationLink .htmlSonarWiz (wreck search)那样Side scan mosaic, target digitising那样SonarWiz .htmlQPS Qimera (port surveys)那样Difference surfaces, volume, infrastructure inspection那样qps.nl/qimera .htmlHypack Port Module那样Berth scanning, channel monitoring那样hypack.com .htmlROV (VideoRay, SeaBotix)那样Visual inspection of infrastructure那样Manufacturer sites

10. Frequently Asked Questions (with internal links)

What is the best side scan frequency for wreck search?

100‑200 kHz for deep water (>30 m) and long range; 450‑900 kHz for shallow water (<20 m) and high detail. Day 80 side scan covers frequencies.

How do I present under‑keel clearance results to a port authority?

Use a colour‑coded chart: green (>1.2 m clearance), yellow (0.6‑1.2 m), red (<0.6 m). Also report minimum clearance depth. Day 76 final products helps with chart design.

How often should a port channel be surveyed?

For high‑silting areas (e.g., river mouths), monthly. For stable coastal ports, quarterly. After storms, emergency survey. Day 34 time series can predict shoaling rate.

What is the minimum object size detectable in a wreck search?

With 450 kHz side scan, a 1 m high object can be detected at 50 m range. With MBES, a 1 m³ wreck can be seen if grid resolution is ≤0.5 m. Day 81 magnetometer adds ferrous confirmation.

How do I inspect a quay wall without special equipment?

Use a pole‑mounted single‑beam echosounder along the wall, combined with side scan sonar. For verticality, use a total station from the quay top. Day 60 structural integrity covers inspection reports.

11. Action Items & Next Steps

📌 Use the clearance simulator: set object height 3 m, vessel draft 12 m, UKC 1.2 m, depth 17 m – check if safe.
📌 Design a wreck search plan for a 5 km² area (line spacing, frequency, sensors).
📌 Review a port survey report template and note the sections on berth clearance.
📌 Proceed to Day 87: Port & Harbor Surveys – Navigation Safety.

🚢 Day 86: Introduction to Module 14 – Specialized Applications