How keel-hauling moved a sailor beneath a ship

Was keel-hauling carried out across a ship or along its length?

It varied, but in the Royal Navy it was traditionally lengthwise when the ship was under way, with water flow pulling the person beneath the hull.

The exact route depended on the navy and on whether the ship was moving. The Royal Navy's traditional underway method is described as lengthwise, using the ship's motion and water flow over the hull to drag the condemned person along. The answer breaks off before fully describing the stationary method, so it does not support treating one route as universal. Keel-hauling depended on hull movement and local naval practice rather than one standardized technique.