New Sonar Technology Adds a New Dimension to Navigating Passenger Vessels

Foghorn Focus: Electronics & Navigation

Due to the recent publicity regarding San Francisco Bay Area Water Transit Authority's(WTA) incorporation of a three dimensional (3-D) obstacle avoidance sonar system on board the two ferries under construction at Nichols Brother's Shipyard, perhaps the time is right for a deeper look at 3-D sonar and its potential benefits to the passenger vessel industry.

Sonar Technology: Three dimensional sonar technology offers a paradigm shift in how mariners navigate on the water by economically, accurately and efficiently delivering to mariners the critical information they need to safely navigate their vessels. By providing a real-time, 3-D picture of the depths immediately ahead of a vessel, this technology can enable marine vessel operators to avoid costly, dangerous and environmentally damaging collisions and groundings. The introduction of a navigation grade sonar system has an important equivalent to the introduction of marine radar systems during the later part of the 20th century. With the introduction of the first generation of this enabling technology, these new systems are already changing the way mariners navigate through the oceans.

Other navigation technologies, such GPS, RADAR and electronic charts, are widely accepted and are now required equipment on most classes of vessels including passenger vessels. The introduction of and use of navigation grade sonar is not meant to replace these valuable tools, but rather to augment the mariner's box of navigation tools by offering a real time picture of the waters ahead of the vessels. This further enables the mariner to make critical navigation decisions given a more complete understanding of the real time scenario.

Other Navigational Technologies: Until now, state-of-the-art navigation has been to rely on historical charts, GPS systems, and depth sounders to determine position and water depth under the ship. Chart data is often inexact as coastlines and shipping channels can shift. Transient objects such as sandbars, lost shipping containers, ship wrecks, whales, floating logs and other debris are not shown on charts. Additionally, most charts are based on data that is 60 years old or older and predate GPS. This means that even "charted" obstacles are often not where the chart places them.

Echosounders tell ship operators how deep the water was they just drove through but do nothing to warn of the dangers ahead. Radars only tell the user about objects above the water and give no indication of water depth.

Current generations of sonar systems, aside from these new three-dimensional systems, are limited to one- or two-dimensional views, with limited distance capabilities, limited performance in shallow waters, and a narrow field of view. These products are therefore not useful for navigational purposes; yet may still be marketed and sold for this purpose. Although customers of these products understand the need, these products do not solve the problem now fulfill this need. There are no commercial or military sonar systems that can meet the navigational needs of either the commercial fleet or recreational vessels.

Passenger Ferries and High Speed Ferries: 3-D Sonar technology, although still in its early stages, has broad applications and can be used in many areas. This technology is of utmost importance to the passenger vessel and high-speed ferry industries who must balance passenger safety with speed and environmental impact. In these applications, the technology has the potential to provide greater passenger safety. In addition, growing concerns regarding marine mammal mitigation can be alleviated by using this technology. In regards to high speed passenger ferries, which are becoming ever more common for shoreline transportation alternatives, the change of striking endangered marine mammals during transit is an all too frequent occurrence that cannot be tolerated. There is an ever increasing awareness of and intolerance for environmental issues such as shipstrike of marine mammals and oil and other hazardous waste spills.

Over the last several years, the quantity of high speed vessels has increased and is expected to continue to increase. There are now 120+ high speed U.S. Ferries compared to 70 in 2001. the increased amount of these vessels on the waterways translate into an even greater potential for accidents. The U.S. Passenger vessel industry now carries more than 200 million passengers each year. There are over 5700 (over 100 gross Tonnes) passenger vessels (ferries, high speed ferries, cruise ships, day cruisers) with the responsibility of carrying their passengers safely through North American waters estimated at 200 million passengers per year.

Current Limitations: Current 3-D navigation sonars such as being installed on the vessels at Nichols Brothers have a range of over /4 mile. The San Francisco Bay Water Transit Authority recognizes that, although the range and speed of the current systems have limitations, it is the best available technology. Higher speed and longer range systems are on the drawing boards and with continued support from PVA and member companies, these will offer solutions that will meet all of the needs of the industry.

Future Security Applications: One of the greatest threats to passenger vessels is an attack by swimmers, divers, or other underwater threats. A terrorist or other attack carried out by a single person could be capable of delivering enough explosives to damage and cripple passenger vessels with resultant loss of lives. Various technologies enable surveillance and deliver security against air and land attacks, but there is a lack of a low-cost practical and effective solution to detect or deter an underwater based attack, particularly one by swimmers. Underwater security is one of the most technologically challenging. Threats below the water are difficult to address.

There is a current need in the industry for an accurate, easy to use, low cost system with 360-degree sector coverage. Three dimensional forward-looking sonar technology can be very effectively applied to solve this need and to combat these possible attacks. Although the technology is currently being used for navigation purposes, there are versions of the technology that are being adapted for security applications. These high resolution systems will have the capability to no only locate obstacles (in this case, smaller obstacles that are of concern for navigation), but also to identify the objects as treats or non-threats.

Although advanced swimmer detection systems have been designed for protection of critical/high value assets, these systems traditionally have been very expensive ($500K - $1M+), often have high false alarm rates, are difficult to deploy, require extensive user training, and have limited range capabilities. A 360-degree Ship Protection System (SPS) based on 3-D sonar technology offers a practical, accurate solution.

Conclusion: The need for a navigational solution to groundings and collisions has been recognized for hundreds, if not thousands of years. We expect that navigation grade sonar will become increasingly attractive to operators of all large ships. Three dimensional sonar technology represents an extraordinary advance in sonar technology, and represents a revolutionary change in the way vessels navigate.

In Summary: The benefits for passenger vessel operators using 3-D Navigation Sonar will include:

Increased Safety at sea for vessels
and passengers by reducing
navigational accidents at sea.

Reduced maintenance costs
by reducing number of vessel
collisions and groundings.


Environmental protection by
reducing likelihood of high impact
environmental disasters such as
oil spills, reef groundings and
whale strikes.

Economic savings through more
efficient routing, insurance savings
and reduced energy consumption
by allowing ships safe use of most
direct routes.