Mr. Red, that's center of lateral resistance--just to be pedantic.

to be truly pedantic the shape of the hull and the speed alter the centre of pressure, the centre of lateral resistance derives therefrom. Masts on narrowboats are central laterally and forward of the centre (howsoever defined). Towing speeds would not modify the centre of pressure by any noticeable measure. The shape of the hull might, who knows?

in the UK boats are 7ft beam (or <), barges (& broad beams) greater than.

FWIW I have put a few videos of Stroudwater renovation on my website canal.mister.red