A single surface with creases can be preferable to a polysurfaces in some situations. A single surface can be edited directly using control points, and a single surface can be rebuilt, have knots removed or inserted, etc as an entity. A polysurface in contrast needs to be exploded before editing, and care is needed to ensure that the individual surfaces can be rejoined.
I use single surfaces with creases when working on boat hulls of lapstrake/clinker or multi-chine construction. An example of a typical shape in both single surface with creases and polysurface forms is attached. GoodCreases.3dm (1.6 MB)
I agree, at the maritime research institute where we use rhino to draw ship hulls on a daily basis, we also work with creased single surfaces. In fact, I recommend my colleagues to run the CreaseSplitting SplitAlongCreases=No command at startup to allow creases in models.
Have you tried the ORCA plug-in? Everything from hydrostatics & stability as well as hull creation to computational fluid dynamic analysis. I use ORCA and have used their developer products since the eighties. Highly recommended especially if you want a single surface Planing hull with chine flats like the quickie I created in less than one minute with their hull assistant which creates hulls that you can easily edit to get what you want with hydrostatics running in the background and updated as you edit the hull.hull assistant example.3dm (572.5 KB)
For single chine hulls I usually work with distinct surfaces for the side and bottom. Also for rounded forefoots I use a different approach with a trimmed surface without any singularities. I use creased surfaces for preliminary work with multi-chine hulls, typically with five or six panel.
