How to use a Sextant

>>> How to use a Sextant


(click for animated version)

Bet you didn’t know one animated picture could show you a bunch about using a sextant. Navigating these days is GPS and other electronic aids for most of us, but having a manual fallback only makes sense, especially if you are really embarking on a voyage.

I don’t recommend this as the be-all, end-all knowledge base, but its an interesting start.

Stick chart navigation

>>> Stick chart navigation


…an awesome, indigenous type of ocean mapping and navigation technology known as stick charts (aka Marshall Islands stick charts, Micronesian stick charts, or Polynesian stick charts).

Really slick way of navigating and making charts… really charting the water flows itself, and not the land masses in that water. Read the article for details and lots more pictures, along with links to other sites if you want to learn more.

What’s wrong with your GPS output

>>> What’s wrong with your GPS output

I didn’t realize until running across this article that the basis for most GPS unit output started with a marine standard – NMEA 0183. Nor did I realize how poorly suited the protocol is for a lot of what people now use GPS units for. Even nautical uses.

If you’re interested in GPS, navigation and especially bits and bytes of computer protocols, you might find this worth a read.

The protocol used by GPS devices to report to computers is a small subset of NMEA 0183. NMEA stands for "National Marine Electronics Association", and the features GPSes use for reporting time/position/velocity information are a small part of a protocol originally designed for communication between parts of complex marine navigation systems. Thus the full protocol includes support for depth sounders, LORAN, and many other things irrelevant to a modern GPS.\

The lowest level of NMEA 0183 is quite sensibly designed. The protocol consists of sentences, each led by a dollar sign and an identifying text tag, followed by multiple comma-separated textual fields, ended by an asterisk, a checksum, and LF/CR. This is a simple, clean format with good extensibility, easy to parse and generate. It is well adapted to its job, which is to pass small amounts of numeric and status information. The textual format makes it easy to log NMEA sessions, edit them, and play them back — a substantial advantage in developing talker and parser software.\

Unfortunately, the good news ends there. The design of the upper layers of NMEA 0183 is patchy, kludgy, and replete with the kind of errors that arise from growth by accretion rather than forethought.

Urban Ocean Observatory at the Center for Maritime Systems

>>> Urban Ocean Observatory at the Center for Maritime Systems


This is a slick set of web pages provided by the Stevens Institute of Technology. Wind speed, currents, water levels… all kinds of stuff.

The New York Harbor Observing and Prediction System (NYHOPS) was established to permit an assessment of ocean, weather, environmental, and vessel traffic conditions throughout the New York Harbor and New Jersey Coast regions. The system is designed to provide a knowledge of meteorological and oceanographic conditions both in real-time and forecasted out to 48 hours in the Hudson River, the East River, NY/NJ Estuary, Raritan Bay, Long Island Sound and the coastal waters of New Jersey. In this web site you will see graphic images of: water level; surface and bottom temperature; surface and bottom salinity; surface and bottom currents; NOAA winds; coastal waves – height, period and direction; CDOM (Chromophoric Dissolved Organic Matter). Newly added is Acoustic Tranmission Loss

NavQuest – Marine Navigation Made Easyâ„¢

>>> NavQuest – Marine Navigation Made Easyâ„¢

Billed as the "Home of Online Marine Trip Planning" this is an interesting site with various boating, scuba and even user uploaded videos and photos. They have lots of navigation "stuff" with interactive charts and other resources that are worth a look. Its not a full navigation suite, but for some route planning and dreaming, it might be just the thing.