Marine Habitat Mapping — Marine Resources Consultants
Summary: Marine Resources Consultants built a real-time eelgrass mapping system for Washington State’s ferry expansion using WinWedge to parse live Trimble GPS output — via an NMEA multiplexer — into a Microsoft Excel chart. This plots the survey vessel’s position and habitat observations as they happen, cutting data collection and analysis time in half.
The Challenge
Washington State’s ferry system expansion required new docks in Puget Sound — and under the state’s “no net loss” marine habitat policy, any construction that might affect eelgrass meadows needed precise mapping of where eelgrass actually grows. Before implementing this real-time system, crews collected position data by hand on the water and built charts back at the office afterward: slow, tedious, and with no way to see coverage gaps until the boat had already gone home.
The Solution
The survey vessel carries an underwater video camera watched by the helmsman on an onboard monitor. A Trimble GPS receiver feeds an NMEA multiplexer connected to the PC’s serial port, where WinWedge parses and filters the position stream and directs it into Excel. The spreadsheet plots three live data series: the vessel’s current position as a moving crosshair, the track line where eelgrass is present (thick green), and where it’s absent (thin black). When eelgrass appears or disappears on the video monitor, the helmsman clicks an ON/OFF button embedded in the spreadsheet — producing a finished, geo-referenced habitat map in real time, on the boat.
The system helped WSDoT expand its ferry terminals with no net loss of eelgrass, and one terminal project earned the U.S. Department of Transportation’s Distinguished Environmental Achievement Award for Research.
The Results
- 50% reduction in data collection and analysis time
- Accurate correlation of habitat observations with GPS position
- Live map on board — coverage gaps visible and fixable during the survey
- Award-winning environmental outcome for the ferry expansion
How You’d Set This Up Today
GPS receivers still speak NMEA, and WinWedge still parses it into Excel and any Windows application in all the latest versions of Windows. Today the GPS data would usually arrive through a USB virtual COM port (using an RS232 to USB converter cable and driver).
In remote locations the data can be transferred via satellite IP networked receivers. TCP-Wedge (part of WinWedge Pro) would input the networked GPS or device data into Excel.
Excel’s live charting works the same way today, and the click-a-button-to-tag-observations technique applies to any survey where a human observation needs to be stamped with position and time: wildlife counts, depth soundings, agricultural scouting, utility inspections. Several instruments can feed the same workbook at once by running multiple WinWedge (or TCP-Wedge) instances.
Collecting Data from Your Own Instruments?
Working with GPS, sonar, or any NMEA instrument? Download a free WinWedge or WinWedge Pro/TCP-Wedge trial or call (800) 722-6004 — we’ll help you parse your receiver’s output data into exactly the fields you need.
Originally published in our application archives · Updated August 2026
Additional Notes:
Minimizing the environmental effects of our expanding population presents one of today’s most difficult challenges. How do we balance economic growth and environmental safety? The problem is particularly acute for booming coastal communities where waterfront development threatens critical marine environments, such as eelgrass meadows.
In the Pacific Northwest’s Puget Sound area, global positioning systems (GPS) and geographic information systems (GIS) are supplying a way for development and scientists to meet this challenge. The Washington State Department of Transportation (WSDoT) is relying on GPS and GIS to help protect critical nearshore marine habitats — primarily eelgrass — while the agency expands and improves its ferry system. The ferry system, which in 1995 transported more than 24 million passengers and vehicles across the Puget Sound, is consistently overloaded, resulting in two to three hour waits during the peak summer tourist season. WSDoT is addressing the overcrowding by constructing three new jumbo ferries, adding two more passenger-only boats, and expanding several terminals to accommodate the additional demand. However, WSDoT had to find a way to provide these improved services while also satisfying local residents’ desires to protect the natural environment they moved there to enjoy.
In fact, the State of Washington is so serious about environmental preservation, that in 1989 the Washington Department of Fish and Wildlife adopted a “no net loss” program for all marine habitats. Any waterfront construction project that might cause a loss of eelgrass must get a Hydraulic Project Approval. The ferry system expansion falls under this policy since it calls for the construction of new docks, which can threaten eelgrass by blocking the light the vegetation needs to survive.
Eelgrass mapping system
The first step in protecting eelgrass is mapping where it is. Marine Resources Consultants developed a creative, low-cost, real-time mapping solution to chart the proposed expansion areas. The consulting company’s solution utilizes a GPS-based underwater video graphic mapping system that is plotted in a Microsoft Excel. The basic idea is pretty simple, the crews’ helmsman monitors the underwater video camera on a TV screen in the boat. The GPS Receiver (manufactured by Trimble, Sunnyvale, CA) is connected to NMEA multiplexer, which is connected to a computer running Microsoft Excel and the WinWedge. WinWedge parses and filters the output from the GPS Receiver and directs it to the spreadsheet program.
The spreadsheet plots three data series. The first is the current longitude and latitude plotted in red with a black cross-hair in the middle, indicating the current vessel position. The other two data series consist of longitude and latitude coordinates for the vessel track line when eelgrass is present, indicated by a thick green line, or absent, indicated by a thin black line. The helmsman simply clicks on a eelgrass ON/OFF button embedded in the spreadsheet when eelgrass appears or disappears on his monitor. The result is a real-time plot of the area sampled that indicates where eelgrass is present.
The system has been used to help WSDoT expand its ferry system with no negative effects to the area eelgrass. The system is so impressive that on Earth Day in 1997, the US Department of Transportation awarded one of the terminal expansion projects the Distinguished Environmental Achievement Award for Research.
Before discovering WinWedge, data was collected by hand and charts were created on a PC back at the office. Users of the system noted that the process was significantly more time consuming and tedious before development of the real-time system.