The formal investigation put the time elapsed, from the instant of collision at 1.46 a.m. to complete immersion at close to 30 seconds. Witnesses quoted in the investigation described the Bowbelle as "hitting it [the Marchioness] in about its centre then (mounting) it, pushing it under the water like a toy boat."
The Captain of the Bowbelle, Douglas Henderson and his Second Mate were immediately put under arrest and taken to a nearby police station for questioning. At the time it was assumed (albeit wrongly) that the Marchioness had steered into the path of the Bowbelle as both vessels were using the centre of the river. This allegation was disputed by survivors’ testimonies many which stated that the dredger collided with the Marchioness.