The CCG uses the AP1 –88 hovercraft in two different sizes each craft has two lift engines and two thrust engines. The larger 400 class will carry a fully loaded pumper truck.
The hovercraft creates a depression in the surface of the water and will create it’s owns bow wave up to around 15-20 kts after which the hovercraft can break through the wave and become a truly “dynamically operated craft”, we call it “hump speed”. It is this effect that is used for breaking the ice, the craft stays just below hump speed, creating a significant bow wave, the wave travels under the ice both lifting the ice and removing support from it and the weight of the craft contributes to the cracking process. This is used to prevent ice jams in the rivers back east, but I seem to remember that the effect is limited to a certain thickness and would have to be new ice. Hovercraft can not operate in an area with heavy ice ridges. But Hovercraft do benefit from scaling up as they can carry significantly more weight, but the limiting factor is your ability to jack it up to do skirt repairs.
The drawback of this effect is called “shallow water effect” where the bow wave becomes significantly higher in shallow water and will prevent the hovercraft from breaching it’s own wave. This effect was more prevalent in the older, smaller SRN6 hovercraft with one engine and if you watched them you would notice that the pilot will climb up onto the beach to pick up speed before crossing into the water. Hovercraft will actually go faster over land, ice than water, but the SRN6 was limited to 30kts (max speed when new was 60kts) over land in case of engine failure I spent most of my time in SRN6 hovercraft and the AP1-88 came in just as I changed jobs.
The Royal Marines use the Griffion, about the size of a SRN6
By the way real men drive SRN^’s the AP1-88 are for pussies!!! ;D ;D