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Comment by tauntz | Hacker News Reader

Hydrofoiling boats have been in commercial use for quite some time. I've taken one[1] between Estonia and Finland a couple of times but these are sadly not operating anymore.

1. https://images.delfi.ee/media-api-image-cropper/v1/02cc3aa0-...

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The Greek apparently still operate hydrofoil boats between islands on Mediterranean sea. Sea, not river.

Same in Italy. Both sea and lakes.

I recall a hydrofoil on Lake Garda -- obviously lots of power required -- it was much louder than the normal ferries on that lake.

Some hydrofoil ships are powered by turbines, which produce a high-pitch whine, much more noticeable at a distance than the low-frequency rumbling of a diesel.

I talked to the skipper of one. He said the boats (Linda Line) had been in service in the Black Sea.

jet foil in Japan https://www.youtube.com/watch?v=e_lKISuF5Y4

edit: shorter video

I think that's a Boeing 929 Jetfoil. They've been going since 1974 https://en.wikipedia.org/wiki/Boeing_929_Jetfoil

What are the economics of hydrofoils like? I recently watched a YouTube video covering the rise and fall of hovercraft ferries. Basically, the lower reliability of hovercraft eventually overwhelmed the utility of faster transit times. Is it the same for hydrofoil ferries?

Hi there, Mikael at Candela here. Since the P-12 uses 80% less energy than a conventional vessel, the cost of operating it is far less than diesel vessels- overall around 50% percent lower including service, energy, salaries etc. This makes electrification desirable for operators for the first time. Usually, conventional (non-foiling) electric vessels are more costly to purchase than diesel vessels, and more costly to operate too, as they require MW charging infrastructure on land. The P-12 uses a DC style charger of up to 175 kW, which is pretty affordable to install.

They must be much more efficient than both boats and hovercraft - they don't need to keep the air cushion, and they don't need to push their full tonnage away from their path - lift losses excepted, they must be equivalent to much smaller boats.

I would expect to see more of these as recreational vehicles, as they must be much cheaper to operate and, with recreational boats having a much lower duty cycle than, say, BEVs, solar recharging becomes attainable, as long as you keep the boat docked or anchored and charging for much longer than you use its propulsion.

I saw a single person standup foil on a local lake. They look unreal, almost unbelievable in operation. Like someone is flying over the lake. Search for efoils on youtube

This does sound approachable. From my experience, people with lake front property and docks with boat "houses" are clear from any obstruction of direct sun. Line the roof of said boat "house" with solar, and in the typical weekender/vacationer use of a boat, seems pretty managable. However, when the sun is up to be charging is typically the time of the boat's use so it won't be on the charger. Use the solar to charge a powerwall type of solution, and then charge the boat at night?

Solar panels could be on the boat itself, but I am assuming solar won't be able to do much recharging while the engine is in use anyway. OTOH, very few boats are used, or moved, every day.

I imagine a boat would have a hefty battery pack anyway, to power a stove, fridge, air conditioning, plus essential bridge equipment.

I think we're talking different sized boat on a lake. Do house boats typically power from battery or from a generator? I have no familiarity with those.

Most houseboats are barges with no propulsion. They use shore power but often have a backup generator. Having some solar or a small wind turbine is relatively common too.

Yes. I was thinking "river boat with limited propulsion that is moved when the owner wants a change of scenery".

Boat houses are extremely heavy, for obvious reasons. Hydrofoil requires light construction, so these two are not compatible (plus it only works at speeds you would not want to have a house moving at).

I remember reading articles about the Silja Line ferries needing repairs all the time. But that might have been an issue with the specific models and not an indication of hydrofoil reliability in general.

A Boeing 929 Jetfoil with ~450km range, ~300 passengers, 2x Rolls-Royce Allison turboshafts is often quoted to be ~$60M. Tickets are $35-$120. Many routes operating it has been seeking government subsidization to build replacements as hulls near ends of life; so far, only one 929-117 has been built since the turn of the century.

IOW, not a lucrative business on its own, makes _some_ sense as a subsidized public transportation.

On the Thames: https://www.londonreconnections.com/2020/soviet-fleet-on-the...

I took one from Tangier to Gibraltar, in the 1970s (Might even have been the 1960s).

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