Hovercraft

How hovercraft work

The Canadian Coast Guard uses hovercraft, also known as air-cushioned vehicles as part of its fleet. There are two icebreaking hovercraft used for spring icebreaking operations, based in Quebec: the CCGS Mamilossa and CCGS Sipu Muin. The start of icebreaking operations is different every year depending on the weather.

Hovercraft are not conventional icebreakers. Because they float above the surface of the water and are not submerged, they can travel outside the main navigation channels and in shallow waters. The hovercraft’s weight and speed create strong waves that break the ice into smaller pieces, which allows wind and currents to clear the ice away. These operations are important to prevent flooding by preventing the formation of ice jams and promoting good water flow.

The icebreaking process

The hovercraft starts icebreaking operations downstream in the river and proceeds upstream to ensure that ice is flushed away from problem areas. This prevents ice from clogging the entry. It allows for a better flow of water and ice which, in turn, allows the hovercraft to generate more effective waves. The more water in a hovercraft’s area of operation, the greater waves it can produce.

More water also helps protect the hovercraft and its crew, by decreasing the likelihood of getting stuck between two ice jams or in a pile of descending ice. Hovercraft pilots are very experienced. While reducing flood risk is important, the safety of each pilot’s crew and the vessel is always a priority.

Operational considerations

Certain conditions are essential for hovercraft icebreaking operations:

• The ice must not be aground or in contact with the riverbed.
• There must be enough water under the ice to create waves.
• The ice must not be supported by the shoreline.

Hovercraft cannot operate at all times. They must take into consideration:

• Temperature: hovercraft are limited by cold temperatures. Ice buildup on the structure and propellers can cause major damage and halt operations.
• Wind: strong winds can make hovercraft maneuverability difficult, especially when operating in narrow parts of a river.
• Visibility: hovercraft need daylight visibility to work safely in near-shore and/or shallow areas.
• Tides: tides affect the waves generated by hovercraft and cause ice to float or run aground in some areas.
• Ice conditions: ice must be thin enough to crack under the impact of the hovercraft’s waves. Ice that is too thick for the water level or supported by the shoreline can hinder icebreaking efforts.
• Fuel: hovercraft need to refuel daily, but a lack of refuelling options may cause operational delays. Hovercraft are also more effective with more fuel because a heavier weight can create bigger waves for icebreaking.

More information

• Canadian Coast Guard's new Air Cushion Vehicles

You can learn more about the Canadian Coast Guard hovercraft as part of our icebreaking fleet.

For questions, comments or requests for hovercraft assistance, contact your regional ice operation centre. Months of operation are subject to ice conditions.