Do I need a small scale chart or a large scale chart?

A small-scale chart shows a large area in less detail and a large scale chart shows a small area in greater detail. A harbor chart is a large-scale chart; a chart of the North Atlantic from Newfoundland to Ireland is a small-scale chart. There are four basic scale categories: sailing charts (crossing an ocean); general charts (coastwise navigation outside off-lying dangers and usually in sight of land); coastal charts (navigation near shore and entering harbors); harbor charts (details of harbors). Chartlets found on some charts and in cruising guides or nautical almanacs may have really large scales. Zooming in to a particular area on a small scale electronic chart may not show the same detailed information that would be found on a large scale chart of the same area.