Library 04 · Waterborne mobility
Why one research firm is predicting cars will be obsolete soon
Some forecasters say the private car is near the end of its run. Most of that debate is about roads. On the coast, the most interesting answer may be on the water.
The forecast
A few years ago the think tank RethinkX published a much-quoted forecast. Its argument was that cheap electric vehicles and shared, on-demand transport would make owning a private car poor value for most people, and that ownership would fall far faster than the car industry expected. The timeline was bold, and it has not played out as quickly as the report suggested. The reasoning behind it is still worth taking seriously: when a shared service costs much less per kilometre than owning, people switch.
The same economics apply on the coast, with one big difference. The sea is already a road, and nobody has to build it.
Electric hydrofoil ferries
Conventional fast ferries are thirsty. A planing hull pushes a lot of water aside, and a lot of fuel goes into the wake. Hydrofoils lift the hull clear of the water on underwater wings, cutting drag sharply once they are up and flying. Pair that with batteries and electric motors and you get a fast, quiet ferry that is cheap to run.
Candela, a Swedish builder, has put its P-12 electric foiling ferry into commuter service around Stockholm, and Artemis Technologies in Belfast has built electric foiling passenger and work boats. These are still early fleets, but the numbers are promising: far lower energy use per passenger than a conventional fast ferry, little wake in sensitive waters and a ride that does not make commuters seasick.
Venice and the hybrid vaporetto
Venice has never had cars in its historic centre, so its public transport has always been waterborne. The vaporetto fleet is old, diesel and noisy, and its wash damages the foundations of the city. Hybrid and electric water buses have been trialled on the lagoon, running quietly on batteries in the narrow canals and on diesel or charging on longer lagoon crossings. The lesson for other cities is that water transport works when it is frequent, cheap and quiet enough that people forget it is a boat.
Coastal fast catamarans
Along the Croatian coast, catamaran passenger lines link Split with the islands and run on to Dubrovnik in summer. In our own gulf, small passenger ferries cross from Trieste to Muggia and, in season, along the coast to Grado. For many trips they beat the car outright, because the coast road is slow, the parking is scarce and the ferry goes in a straight line.
| Factor | Coast road by car | Fast ferry |
|---|---|---|
| Route | Follows the shore, every bay | Straight line across |
| Summer traffic | Queues, closures, no parking | Fixed timetable |
| Infrastructure | Roads, tunnels, bridges | A quay at each end |
| Energy per passenger | Varies with occupancy | Low when full and foiling |
What it means for surveyors
New vessel types bring new things to inspect. Electric ferries carry large battery banks that need thermal and fire protection checks. Foils and struts take high loads and need careful inspection for fatigue cracks. Aluminium and composite hulls, common on fast ferries, need the ultrasonic and moisture methods we already use on yachts. The tools carry over. The judgement has to be learned again for each new type.
Will cars become obsolete? Not on every road, and not as fast as the boldest forecasts said. But on a crowded coast, a quiet ferry that leaves every twenty minutes is already changing how people move. If you want to see why a displacement hull has a natural speed limit and a foil does not, put your own numbers into our hull speed calculator.