What projections do the charts have?
The NOAA charts can be in any of the following projections: Mercator, Lambert Conformal Conic, Transverse Mercator, and Polyconic. Each projection type will have some parameters associated with it that minimize the distortion for that chart. Examples of these parameters include: latitude of true scale; central meridian; and standard parallels. The parameters are likely to be different for any two charts, making it can be difficult or impossible to put two charts in the same view. See the section on Multiple Charts in a view for more details on the problems associated with projections and multiple charts.
