Ship Ahoy!: Assisting safe passage for ships in Port Phillip Bay
Page last updated:14 March 2025
The Challenge
A sea pilot, maritime pilot, marine pilot, harbor pilot, port pilot, ship pilot or simply pilot, is a mariner who has specific knowledge of an often dangerous or congested waterway, such as harbours or river mouths. Maritime pilots know local details such as depth, currents, and hazards and after boarding a ship by pilot launch or helicopter, temporarily join the crew to safely guide the ship's passage.
Pilots must have expertise in handling ships of all types and sizes and be licensed or authorised by a recognised pilotage authority. In Victoria, all companies offering sea pilot services must have their vessels and pilots registered with Safe Transport Victoria. The maritime industry has always been a pioneer in navigation technology. For a long time, the maritime industry has embraced GNSS to determine latitude and longitude, and with SouthPAN, the accuracy of that service is now improved.
Port Phillip Sea Pilots (PPSP) started operations in 1839, are a privately owned Australian company and employ the largest number of pilots in Victoria. PPSP are sophisticated users of GNSS equipment as accurate positioning is an integral part of their role in guiding large ships around Port Phillip and Western Port bays. Their Portable Pilotage Units (PPU) contain a Global Navigation Satellite Systems (GNSS) receiver and are used in piloting operations to improve situational awareness, aid decision-making and provide recordings for training and investigation purposes.
Hazards to shipping in Port Phillip Bay include:
- The entrance to the bay itself – The Rip. For large ships the deep navigable channel, or Great Ship Channel, is only 245 m wide with reefs on either side. The tidal flow in and out of the bay is severely restricted to the extent that at times there can be a substantial difference in the relative water levels between Port Phillip and Bass Strait. Consequently, the tides run very fast in both directions and can effectively run across the bay entrance, making navigation treacherous.
- Traffic in the bay – some 5,800 large commercial ships pass through the bay each year. In addition, the bay accommodates a significant number of recreational watercraft. To help manage all this traffic and avoid collisions between vessels, there are shipping channels and transit only zones. The water in the bay is not that deep and over time the bay receives silt through its rivers and as run-off. In the past, shipping channels have been dredged to maintain safe water depths.
- Bridges – the West Gate Bridge crosses the Yarra River. Ships heading to the port must pass under the bridge. The Port Authority mandates a maximum 50.1 m above water draft for ships, regardless of the state of the tide. Some of the larger ships can be close to that limit.
- The dock areas – the areas themselves are relatively small with large ships moving in and out at all times of the day and night. Ships must manoeuvre to and from their allocated dock, which usually involves turning the ship around. The Yarraville Swinging Basin has a diameter of 274 m; the Swanson Swinging Basin has a diameter of 342 m; the Appleton Swinging Basin has a diameter of 330 m when ships are alongside. As ships get bigger – from 250 m to a maximum of 360 m with routine visits from ships 337 m in length – some of these swinging basins can no longer be used to turn a ship, and the tolerances become tighter in those that can be used.
The work of the pilot is to mitigate the possibility of an adverse event occurring. Adverse events include:
- Collisions between ships
- Ships running aground in the bay or river
- Ships colliding with infrastructure at the port or around the bay
- Loss of control of a vessel leading to disruption in channels and transit zones
- Depending on the nature of the adverse event, the consequences can include:
- Death or injury to people involved in the event
- Creation of pollution harming people and wildlife in the bay
- Loss of a vessel
- Damage to infrastructure which must be repaired
- Loss of cargo into the water
The Solution
Two PPUs, one SBAS enabled, the other not.
Sea pilots mitigate the risks associated with these hazards through the application of their knowledge about the conditions of an area and the assistance of a PPU. The PPU relies on GNSS and calculates the real-time position, course and speed of the ship and places that information in the context of a maritime chart displayed on the PPU’s screen. The Sea Pilot uses their PPU as an aid to navigation and to assist in maintaining constant situational awareness as they navigate the ship to and from its dock. While absolute position accuracy is of great importance to marine pilots, including height above water, of equal importance is the calculation of heading (the direction in which the ship is moving) and rate of turn, course over ground and speed over ground.
The Southern Positioning Augmentation Network (SouthPAN) is a free, open access public service that improves the accuracy of GNSS, like GPS, from 5-10 metres to less than a metre, and in some cases as little as 10 cm. This joint initiative between the Australian and New Zealand Governments is the first satellite-based augmentation system (SBAS) in the Southern Hemisphere and provides the opportunity for businesses and communities across both countries to benefit from precise positioning and navigation. With the PPU enabled to received SouthPAN signals, the demonstration shows the potential for SBAS services to complement the RTK solutions that Maritime have traditionally used.
The Impact
The PPU positioning with standalone GNSS achieved a horizontal accuracy of 1.1m and a vertical accuracy of 3.2 m. The PPU positioning augmented by SouthPAN L1 SBAS corrections provided an improvement over the standalone, achieving an accuracy of 0.8 m and 2.1 m in the horizontal and vertical domain respectively. The accuracy improvement is particularly notable in the vertical domain, with its position accuracy improving by 34%. The L1 SBAS 95th percentile results meet the performance requirement targets set out in the SouthPAN Service Definition Document (Geoscience Australia & Toitū Te Whenua Land Information New Zealand, 2024).
Further, the Precise Point Positioning via SouthPAN (PVS) results show significant improvement over both the standalone and L1 SBAS results, achieving a 0.19 m horizontal accuracy and 0.44 m vertical accuracy. In this demonstration, PVS has also met the performance requirement targets set out in the SouthPAN Service Definition Document. These results suggest that in the short-term, implementation of L1 SBAS will provide an immediate benefit to the accuracy achievable by PPUs using standalone positioning; and in the longer term, PVS implemented into a suitable on-board or portable Pilotage system has the potential to significantly improve upon the performance of L1 SBAS.
The benefits to Sea Pilots of using the SouthPAN services include:
- For certain piloting operations, not involving the largest of ships, the L1 SBAS position augmentation offers a level of accuracy that is commensurate with the piloting task.
- The L1 SBAS service is delivered via satellite and does not need an internet or UHF base station connection.
Being able to complete some piloting tasks without RTK would mean:
- Money is saved on some RTK service subscription costs.
- The administration overhead of managing subscriptions across many devices may be reduced.
- Using SouthPAN simplifies operations – PPUs just need to be turned on for the service to work.
As the SouthPAN program develops to full operating capability in the coming years, with compatible devices become more readily available, the PVS service will become a viable alternative to RTK.
Port Phillip Sea Pilots have used the SouthPAN L1 SBAS service in operations. It provides a cost-effective way of allowing marine pilots to receive some corrections for their GNSS devices to improve accuracy without the need for internet access or a UHF base station as is usually the case to obtain RTK corrections.
Jon Dicker, Marine Pilot, Director, Port Phillip Sea Pilots