# The impact of underwater waves on ship manoeuvrability: a case study in a fjord

## TL;DR

A 2019 ship collision in a Canadian fjord may have been caused by underwater waves, which can affect ship maneuverability during docking.

## Contribution

This study provides empirical evidence that underwater waves in fjords can impact ship maneuverability and safety during docking.

## Key findings

- Underwater waves with wavelengths of 50-100 meters and wave heights of 1-3 meters were observed in the Saguenay Fjord.
- Wave-induced currents of 0.1-0.3 m/s near the wharf could affect ship movement during docking.
- Large ships like the Jaeger Arrow may generate their own underwater waves, potentially compromising docking operations.

## Abstract

In 2019, the Motor Vessel Jaeger Arrow collided with the Grande-Anse Terminal wharf (Saguenay Fjord, Canada) during docking from unknown causes. However, the timeline of the incident and the ship’s behavior during docking suggest that underwater waves may have caused the collision. Data collected in 2023 using a camera and thermometers confirmed that this area of the fjord regularly experiences underwater waves with wavelengths ranging from 50 to \documentclass[12pt]{minimal}
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\begin{document}$$100~\textrm{m}$$\end{document}, wave heights of 1 and \documentclass[12pt]{minimal}
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\begin{document}$$3~\textrm{m}$$\end{document}, and periods of around \documentclass[12pt]{minimal}
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\begin{document}$$2~\textrm{min}$$\end{document}. These waves frequently collide with and reflect off the wharf, generating currents of 0.1 to \documentclass[12pt]{minimal}
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\begin{document}$$0.3~\textrm{m}\,\textrm{s}^{-1}$$\end{document}. Numerical simulations further illustrate the interactions between the waves and the wharf, highlighting regions near the wharf where wave-induced currents, both inshore and offshore, occur, including areas with near-zero currents that could create a false sense of calm conditions. Importantly, our observations also revealed that large ships, such as the Jaeger Arrow, can generate their own underwater waves, potentially compromising docking operations. While we cannot definitively confirm that underwater waves caused the incident involving the Jaeger Arrow, our study offers a plausible explanation: the ship may have been caught in a wavetrain reflecting off the wharf, leading to unpredictable movement during docking. These results highlight the potential risks posed by underwater waves to ship safety and maneuverability during docking operations, a topic under-explored in existing scientific literature.