The naval battle of Actium and the myth of the ship-holder: the effect of bathymetry

TL;DR

This study combines historical analysis and modern fluid dynamics to explain how shallow water conditions at the Battle of Actium influenced ship movement and the myth of the remora fish stopping ships.

Contribution

It reveals how bathymetric features affected naval tactics and ship resistance, linking ancient legends to physical phenomena through scientific measurements and modeling.

Findings

Shallow water increased wave resistance for galleys.

The wake pattern resembles the remora fish's adhesion mechanism.

Bathymetry at Actium influenced naval engagement dynamics.

Abstract

A myth of antiquity is explained with modern science in the context of an ancient naval battle. A legend was invoked by the admiral Pliny the Elder to explain the defeat of Antony and Cleopatra against Octavian at the naval battle of Actium. A fish, called echeneis or remora, is said to have the power to stop ships or to delay their motion by adhering to the hull. Naturalists have since studied how the fish sucking-disk with its typical pattern of parallel striae sticks to its host. Here we show the pattern of the free surface measured in a towing tank in the wake of an ancient galley is similar to the striae pattern of the fish. We have measured the bathymetry at the mouth of the Ambracian Gulf that influenced the physical environment of the battle. The computations demonstrate the increase of wave resistance of a galley as a function of the draft to the water depth ratio in shallow water corresponding to the appearance of a particular wake pattern: the echeneidian free surface pattern.