(Continued from page 21) Information gathered from hydrographic surveys go into creating nautical charts like this one for an area near Florida's Tampa Bay. NOAA conducts hydrographic surveys to maintain over 1,100 nautical charts. (Photo Credit: NOAA) tion). Early hydrographic surveyors used a hand-held rope, weighted at one end with a 10-pound piece of lead, to measure depth. This so-called "lead line" had graduated depth markings that a leadsman lowered until it touched bottom when he would read and record the depth manually. This measure of depth is known as a sounding. Surveyors determined positions where they took soundings by three-point sextant fixes to mapped reference points on shore. This was a labor intensive and time consuming process. While the measured depths were accurate, they were limited in number. Information between the soundings was missing, so that mariners would often be unaware of bottom features and depth information necessary for navigation safety. This year NOAA celebrates the 200th anniversary of its founding, born in 1807, when President Thomas Jefferson founded the U.S. Coast and Geodetic Survey (as the Survey of the Coast) to provide nautical charts to the maritime community for safe passage into American ports and along our extensive coastline. To help NOAA celebrate, each edition MTR will focus on a significant person, technology or event from the organization's history. In the June 2007 edition, MTR will offer an in-depth feature which explores NOAAs varied and storied history. Confidence www.tenix.com Airborne Lidar Bathymetric Survey Tenix LADS owns and operates the latest generation Laser Airborne Depth Sounder (LADS) MkII lidar system, internationally recognised as the fastest, most efficient tool for bathymetric survey in shallow coastal waters. · High Quality Waveforms to depths of 75m · Seamless Coastal Survey Capability to 50m Above Sea Level · Rapid Deployment · IHO Order 1 Compliant Data · High Quality Hydrographic Products · Globally Proven. Australia Tel: +61 8 8300 4447 E-mail: firstname.lastname@example.org United States Tel: +1 228 594 6800 E-mail: email@example.com United Arab Emirates Tel: +971 4 347 3497 E-mail: firstname.lastname@example.org www.seadiscovery.com Marine Technology Reporter 25
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