Beta test of crowdsourced bathymetry holds promise for improving U.S. nautical charts

We are on the verge of acquiring a significant new source of data to improve NOAA nautical charts, thanks to an enthusiastic industry and mariners equipped with new technology.

By Lt. Adam Reed, Integrated Oceans and Coastal Mapping (IOCM) Assistant Coordinator

The United States has about 3,400,000 square nautical miles of water within our coastal and Great Lakes jurisdiction. Coast Survey, who is responsible for charting that vast area, averages about 3,000 square nautical miles of hydrographic surveying each year. The data collected by those surveys update over a thousand NOAA charts. However, hydrographic surveys are expensive and laborious, and so Coast Survey directs them toward the highest priority sites, which leaves many coastal areas without updates for many years.

Coast Survey may soon get new sources of information, provided voluntarily by mariners, which will alert cartographers to areas where shoaling and other changes to the seafloor have made the chart inaccurate.

Rose Point Navigation System beta tests new crowdsourcing database

Technology has reached the point where any boater can buy an echo sounder kit, add a GPS system, record depth measurements, and make their own geospatial observations in a common reference frame. The question then for hydrographic offices (who are concerned with improving nautical charts for safe navigation) becomes “how do we take advantage of that?”

Rose Point Navigation Systems is working with system developers at NOAA’s National Centers for Environmental Information (NCEI) and with hydrographic experts at Coast Survey and others who are collaborating on an international effort to maintain crowdsourced bathymetry. In a beta test released on May 13, 2016, Rose Point has added a new feature to Coastal Explorer that gives users an option to send anonymous GPS position and soundings data to a new international database managed by NCEI. After getting permission from users, Rose Point systems will generate data log files of positions, depths, and time, and automatically transmit the files to the data center, where Coast Survey can pull the data to compare it to nautical charts.

Crowdsourced bathymetry is an international project

Using data from private sources is not new for Coast Survey. Private interactive cruising guides and other internet-based enterprises have set up services that allow commercial mariners and recreational boaters to share information about navigation hazards they see (or experience) while on the water. The United States Power Squadrons and the U.S. Coast Guard Auxiliary have a decades-long tradition of sharing updates through our cooperative charting programs. But the lack of appropriate software and integration between sources has hampered efforts to use the information to its full potential.

Hydrographic offices around the world are re-thinking crowdsourced bathymetry. In October 2014, Coast Survey led the U.S. delegation to the Fifth Extraordinary International Hydrographic Conference, with Rear Admiral Gerd Glang at the helm. At this meeting, the U.S. and France jointly proposed an initiative (see Proposal No. 4) that introduced crowdsourced bathymetry as a recognized source of data for nautical charts. One of the results of that initiative was the formation of the IHO Crowdsourced Bathymetry Working Group (IHO CSBWG) that set out to develop crowdsourcing principles and guidelines, and then offer a platform for sharing best practices around the world.

Working hand-in-hand with NCEI, the working group has developed a database that can receive volunteered bathymetric data. Data can come from anyone in the world, and everyone can access it.

Coast Survey will use crowdsourced bathymetry to assess chart accuracy

Crowdsourced reports serve an important role in focusing attention on trouble areas. The data helps cartographers determine whether a charted area needs to be re-surveyed, or if they can make changes based on the information at hand. Even with very sparse data, cartographers can make improvements to nautical charts.

Agreeing in principle to use crowdsourced data is much different than applying the system to the vigor of data transmission from moving vessels, however, so Coast Survey experts contributed hydrographic expertise and system testing. Using Rose Point’s Coastal Explorer, Coast Survey Research Vessel Bay Hydro II transmitted “crowdsourced” data using log files that were automatically produced by the electronic charting system software. (Bay Hydro II is Coast Survey’s primary platform to test and evaluate new hydrographic survey technologies.)

BHII bathymetric data collection
Coast Survey Research Vessel Bay Hydro II collected about 123,000 soundings, over 12 days, to pre-test the efficacy of Rose Point beta test for bathymetric crowdsourcing.

“When you aggregate crowdsourced data, we can expect to see trends develop where the seafloor has likely changed from charted data,” explains Lt. Anthony Klemm. “Using Bay Hydro II data transmissions, we saw such trends indicating shoaling near the Patuxent river entrance. Similarly, in the approach to Solomons harbor, trends displayed depths deeper than charted.”

It is important to emphasize that Coast Survey does not necessarily make changes to any significant charted feature based on crowdsourced data alone. That data, however, is about to become a major factor in making charts better.

8 thoughts on “Beta test of crowdsourced bathymetry holds promise for improving U.S. nautical charts

  1. This is great news! Maybe NOAA will eventually get quality data that will result in faster charting corrections without having to send Bay Hydro II out to verify..Hopefully, this can also promote accuracy in soundings from on board equipment. Too many vessels have no installation compensation for transducer depth, and too many vessels are compensated for depths below the keel. Neither method contributes to accurate soundings for this type of effort. I would strongly urge that some mention be made both at Rose Point and at NOAA that readings should meet a standard that reflects water depth. Obviously, data can be compensated for location, date, and time to correct for tidal height, but there is no way that data can be corrected for some abstract “depth below my keel”, or depth below transducer. Here on the West Coast, it may not seem to be a big issue, but it’s critical in areas like the Atlantic Intra-coastal Waterway. Too many times I’ve heard depths reported over the VHF as ” 2 feet under my keel” or similar when the water depths in the area may not be more than 12 feet. It’s easy to calibrate your sounder. If there’s a good bottom at your slip, like sand, just tie a string to a weight, drop it to the bottom near the placement of the transducer, and mark the waterline on the string. Measure that length and adjust the offset in the sounder set-up until the depth reading matches the measured water depth. The more often you do that in different locations, the better. Clearly, dropping a small lead fishing weight into soft mud will not give good results, nor will a grassy bottom be ideal. Another issue is that the true draft of a vessel is oftentimes not accurate in manuals and brochures. I usually measure the waterline draft of any vessel I run when it is hauled out, and have found many discrepancies for draft, LOA, and beam from the advertised specs.


  2. Reblogged this on Boating Safety Tips, Tricks & Thoughts from Captnmike and commented:
    This a big leap forward in helping to improve chart accuracy, Some charting software vendors will be adding the ability for boaters to enable the saving of GPS and depth information into a database – the data is anonymous with no boat specific identification information. But the data will be used to help find areas where the charted depth is not the same as what boaters are seeing, NOAA can then send a survey party out to survey the area and correct the chart.


This blog is monitored during regular working hours (8 am to 5 pm, ET), and we will moderate comments as soon as possible. Approval of comments offered during evenings or weekends may be delayed.

Fill in your details below or click an icon to log in: Logo

You are commenting using your account. Log Out / Change )

Twitter picture

You are commenting using your Twitter account. Log Out / Change )

Facebook photo

You are commenting using your Facebook account. Log Out / Change )

Google+ photo

You are commenting using your Google+ account. Log Out / Change )

Connecting to %s