The term Ergonomics is not a recognizably nautical one.
However, the principles are an important ingredient in boat design.
Furniture designers put a lot of effort into optimizing the dimensions of a dining chair for the home.
On an unstable platform, such as a boat it is even more important to design furnishings that are not only comfortable but functional.
The furniture makers designing for the mass market have developed a set of average dimensions so their furniture will suit the average person.
These are a good starting point for anyone fitting out a boat.
However, like most things on a boat there will have to be compromises.
However a slope of 20-25 degrees on the inside will increase the comfort for those sitting in the cockpit.
Sorry guys, but it will probably be best to sit this one out.
Even if you do have standing head room in the heads, could you guarantee you aim in a moving boat?
Even when sat, using the heads in a small boat at sea can be a difficult maneuver.
Provide convenient grab handles.
The following dimensions are just guidelines.