Animated Boating Knots by Grog
Authoritative instructional resource for tying knots with amazing presentation technology.
National Oceanic and Atmospheric Administration (NOAA)
Vast collection of regularly updated nautical and weather information.
More than 1,000 nautical charts of U.S. coastal waterways and the Great Lakes viewable on-line using Adobe® Flash® Player.
A series of nine nautical books (print and free download editions available) of supplemental information difficult to portray on charts for navigators of U.S. coastal and intracoastal waters and the Great Lakes.
Forecasts of interest to mariners. Complex—allow time to familiarize yourself with the site.
Cellphone/PDA link: mobile.weather.gov
Current measured and forecast water levels, air and water temperatures, and wind speeds.
A reference manual for navigators, The American Practical Navigator, originally authored by American mathematician Nathaniel Bowditch (1773–1838) in 1802 and now published by the U.S. Government.
Naval History and Heritage Command
NavSource Naval History
Photographic history of the U.S. Navy.
The Art of Rigging 
Historic manual for rigging a sailing ship by Captain George Biddlecombe. #101010[Read online or download PDF 5.38M]
Text-Book of Seamanship, 1891
Interesting historic book, originally written in 1834, explaining many aspects of "the equipping and handling of vessels under sail or steam."
The Engineer's And Mechanic's Encyclopaedia
Historic section about boats from a book published in 1849.