seeing into the future - 3d sonar with chart overlay

Getting real-time data for an extended range of up to 1,000 meters in front of a vessel is now possible with a new type of 3D forward-looking sonar. The ranges of previous sonars were much shorter. That additional distance translates into extra reaction time - a critical advantage in today’s congested shipping lanes.

Linking this innovative technology with nautical charts combines data from two sources to provide a clearer picture of both known and unexpected obstacles. The easy-to-use, color sonar imagery works as an overlay on top of the electronic chart, as has been done for years with radar and Automatic Identification Systems (AIS). 

Vast areas of relatively shallow water are still basically uncharted

When the sonar detects an obstacle, the chart underneath helps the operator to determine what it is and to decide the next step. Is the ship in a restricted channel? Are safe waters anticipated if the vessel turns hard to starboard? Increasing sea hazards make this advanced navigation assistance a vital feature.

Real-time sonar data is an obvious complement to nautical chart data. While digital charts do a good job of showing where things were the last time a measurement was taken, this information could be wrong.

Chart errors
“Charts can be wrong, and many are out of date, and vast areas of relatively shallow water are still basically uncharted,” explains Cheryl Zimmerman, CEO of marine electronics manufacturer FarSounder which developed the extended range sonar navigation technology.

In addition to chart errors caused by things like migrating sandbars and shifting rocks and debris, some old surveys have reefs – and even islands – in the wrong place. There are also uncharted dangers, such as icebergs and lost shipping containers.

“Situational awareness is key for safe navigation,” underlines Paul Elgar, OEM Strategic Business Manager at Jeppesen, which partnered with FarSounder to integrate its charts in their forward-looking 3D sonar system. “As more and more vessels operate in challenging environments and with increasingly crowded seaspace, risk increases significantly.”

The evermore complicated risk scenario makes this advanced forward-looking sonar solution especially well suited for high-value vessels, ships with expensive or dangerous cargo and ships entering fragile marine environment areas. Ships traveling into areas of ice – cruise ships, expedition yachts and commercial ice class vessels – are a current focus. These ships must deal with risk on many levels. Not only is their passenger and crew safety paramount, but the possible environmental impact and high clean up costs that even a small accident could have on the Polar Regions are also critical.

The combination of FarSounder’s sonar technology and Jeppesen’s chart system is already improving navigation on passenger vessels such as cruise ships and ferries, off-shore service vessels, survey vessels who use the equipment to ensure safety when surveying, research vessels operating in both polar and more temperate areas, and even on unmanned surface vessels. 

The “must haves”
The most important elements of a forward-looking sonar system, according to Jeppesen’s Paul Elgar, are 3D capability, coverage zone, fast update rate and easy-to-understand display.

“The sonar must be able to generate a 3D image and determine range, bearing and depth with a single ping,” he explains.

An obstacle can be further investigated with the FarSounder sonar by examining it from various angles from the entire coverage zone in the display. This happens quickly and without moving parts thanks to that single ping. Mechanically scanned sonars, which build an image from multiple pings, take too long to be useful as a real-time navigation solution when quick decisions are a necessity.

In the FarSounder sonar, one single ping is possible thanks to a transducer that allows it to span the whole area ahead of the vessel and create the display.

Elgar adds, “To be an effective navigation tool, a system must have a wide field of view, be capable of detecting obstacles at navigationally significant ranges and also provide depth information.”

FarSounder offers two navigation sonar models, the FarSounder-500 and the FarSounder-1000. The FarSounder-500 has a range of 500 meters ahead with a 90° field-of-view. The 1000 unit has twice this range. Since the transducer must be in the water for it to work, FarSounder’s sonar is generally installed on displacement and semi-displacement hulls. The transducer can remain working at speeds up to 20 knots for the 500 unit and up to 25 knots for the 1000 unit.

A complement to ECDIS
Having an ECDIS on a neighboring screen does not remove the need for a solution that combines sonar and charts; they are actually complementary. 

“In our experience, most operators end up using charting capabilities with the sonar display,” says Zimmerman. “This is because the ECDIS is usually set for a very long range setting on par with the radar’s range setting, while the sonar’s chart overlay is typically set to a different range on par with the sonar’s range setting.”

The charts used in FarSounder’s system come from the Jeppesen Professional+ database, a global vector chart database that seafarers have benefited from for years in ECDIS and ECS systems. The chart data are based on official charts, ensuring their quality and also making sure the appearance of the chart is similar to that on the ECDIS. This increases both safety and simplicity for the mariner.

The mariner is undoubtedly a winner in this ongoing innovation. The ability to see what is underwater ahead of a ship opens up a new dimension to navigation. FarSounder’s system extends the very limited range of other forward-looking sonars to give the navigator enough time to take evasive action when danger is sensed ahead.