Is a hovercraft flying or just performing fast taxiing?
Try taxiing at 50kts on a rough, slippery taxiway! One of the issues for other mariners, when dealing with hovercraft, is visually assessing the track which can vary dramatically from the craft's heading.
The SRN craft were built like aircraft and had expensive gas-turbine engines, so they were fragile and expensive to operate. The second generation craft (AP1-88) were built more like aluminium work boats and had marine diesel engines, so they were much more durable and the operating costs were lower.
I remember my dad coming home one day, very happy because he had discovered that the amber anti-collision beacons on the SRN-6s were the same as those on the "Ryde Council dustcarts". So he was able to buy them from a commercial vehicle dealer for a fraction of the cost of a CAA-approved aircraft part!
I don't know if it is still there, but rather than install radar on each craft, Hovertravel installed a radar on the roof of the Esplanade Hotel in Ryde and in foggy weather, one of the pilots would operate as an "en route and approach controller". The hotel's owner liked to brag that he had the only "radar-equipped hotel" on the south coast!