Wetted surface
From KayakWiki
The wetted surface of a hull is the surface that is in continuous contact with water.
For the same displacement, kayak with longer waterline length will have larger wetted surface than kayak with shorter waterline length.
The reason is simple: geometry proves that the sphere is the shape that holds most volume for the smallest surface area.
Hence boats that are more sphere-like (shorter and rounder) will have less wetted surface than boats that are less sphere-like (longer and narrower)
