Case Study
Incident Investigation
When a boat sinks and allegations of unseaworthiness arise, swift action is essential to uncover the truth. Is a design flaw to blame, or did other factors lead to the incident?
A truckable work boat was assisting with dredging operations in a protected harbor. During a sudden rainstorm, the boat was tied up to the dredge flotilla’s anchor barge with its back end facing the wind and waves.
As the storm intensified, heavy rain and rough waters flooded the back deck, sending water rushing into the engine room, causing the vessel to founder and capsize. One of the three crewmembers had to escape through a window with all three reporting injury during evacuation.
The crew members filed a lawsuit against the work boat's owner, arguing that the boat was unsafe. They claimed the engine room's external door wasn’t watertight, calling it a design flaw that led to the rapid flooding.
Point Cloud Images from 3D Laser Scan Data
Assigned Task:
- Maritime experts reviewed the photographs, videos, and deposition testimony
The naval architects:
- Reviewed the applicable construction and maintenance codes, and United States Coast Guard (USCG) guidance notices for the vessel
- Examined the vessel, taking measurements and photographs
- Completed a FARO 3-D laser scan of vessel’s hull
- Created a 3D hydrostatic model of the hull from the scan data
- Determined a representative wave height and period from the video of the incident
- Analyzed flow of water into engine compartment through a door while open and closed
- Calculated the time to founder based on the inflow rates
The Captain
- Reviewed vessel logs and the operator’s Safety Management System
- Reviewed the standard of care and industry best practices associated with this type of vessel
3D Hydrostatic Model
Evidence was evaluated resulting in the following findings:
- S-E-A’s accurate modeling of the vessel was critical in demonstrating that the actions of the crew members by leaving the hatch open contributed to the conditions that allowed the vessel to founder and go down so quickly.
- The rate of water in flow around a closed, but non-watertight engine room hatch was found to be slow enough that the boat would have taken more than 2 hours to flood the engine room space to the point of foundering. This would have allowed sufficient time to detect the water ingress and evacuate safely.
- With the door open, that time to founder was calculated to be less than 18 minutes. This rapid foundering corresponds with the timeline reported by witnesses and shown in the incident video.
- The engine room door, while not watertight, was shown to be suitable for its intended purpose, thus defending against the claim that it was unsafe.
- Had the tug followed USCG guidance and industry best practices and kept the door closed, or had it been positioned on the other side of the flotilla, it likely would not have foundered at all.