Comment by Candelaboat | Hacker News Reader

Comment by Candelaboat | Hacker News Reader

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Mikael at Candela, the maker of C-7, here. This post is inaccurate and frankly makes no sense. First, the waves will never capsize the boat. Due to low cog, it's virtually impossible to do - we've tried. You can manoeuvre just fine at all speeds, but at high speeds it's correct that you might not be able to avoid running over a log or other submerged objects. Same goes for regular planing boats at high speeds. If you hit something, the foil will withstand smaller objects - branches, debris - but is designed to come off should you hit a bigger object, such as a log. While the foil breaks off, the hull will stay intact and avoid damage. Now, on the other hand, if you hit a log with a conventional boat, there's a risk the hull is pierced and the boat sinks. Regarding the "weight ratio": hydrofoil boats are super energy efficient and need very little power at cruise speed compared to a traditional hull, which is why we use them for C-7. At 22 knots, the C-7 uses about 25 hp, which is pretty remarkable for a 25-foot boat. We have a passenger capacity of six persons, but have actually taken off with 10 persons on board - using a motor rated at 65 kW!

Mikael, my hats off to you and your fine product and sweat you poured into it. My apologies if in any way I seemed to criticize performance of your craft, far from it. I know nothing of it, and electric is going to be the only way in the near future. The context got shifted toward it somehow.

My general skepticism regarding hydrofoils comes from, quite frankly, not seeing that much damage with them because they don't exist 'in the wild' so much here to establish a conventional sense for most U.S. east coast watermen. Plenty of other issues that everyone I know is familiar with, most commonly groundings and striking objects, and occasionally catching cage lines on props. The petrol-era weight bias sticks around and this is where I hope you show us very wrong. I'd love to see some rough water videos of your C-7.

My original response from where everything else stemmed from is that right now this isn't a practical conversion for a common man with something like a 27' cabin cruiser, certainly not in the pocketbook. I do not know how much the C-7 costs, but was my sticker shock that far off?

Hi, no problem, just wanted to clarify. The price is 250 00 euros, which indeed is expensive for a 25 foot boat, but still about 100 000 euros less expensive than conventional electric boats that can go fast - but not that far.

The price stems from a high production cost, the whole boat is built like an aircraft, in carbon fiber (the designer used to work at Eurocopter) to be as light as possible. The weight of the hull and deck is about 240 kg. So our main goal for the future is to reduce the costs - by a lot. But think about C-7 as the Tesla Roadster. But our foiling ferry for the city of Stockholm will be launched next year, and then people using the Stockholm public transport system can go foiling for 2€.

How much does it cost to replace the foils should you tear them off? Because honestly on a pleasure boat say in Florida where I am your not going to hit a log but you will drag bottom at some point due to shallow waters and tides. Most outboards have some sort of skeg damage due to dragging bottom or strikes. Replacing props and lower units or repairing the skeg is very common.

My guess would be treat it like when you pull the chute on a Cirrus GA aircraft. Total loss, but you didn't die!

Mikael at Candela here. The cost of replacing the foils vary, but considerably less than the lower unit of an outboard on 25 foot boats. I actually ran over a submerged chain and broke the foil once - the only time that has happened in Sweden. Took us an hour to replace it, so no big deal You hoist the foil/struts down completely and insert a new one.

Total loss. Even on an alumunium hull, not to mention composite.

Besides, it might not sink, but the collision will throw people around, and it's not like boats have seat belts or people accustomized to using them.

It is really not obvious that it would be worse experience than sitting it with your fiberglass hull. (Clearly worse than an aluminum hull though.) This happens all the time in the Pacific Northwest where I boat, floating logs. Worst are the deadheads, waterlogged so they float vertically just below the surface. Never known anyone to actually sink, but there've been a few destroyed propellers and thousands of bucks worth of hull repair.

Again here in FL dragging sandy bottom is pretty common and most of the time no big deal, maybe scuffing your skeg. Many times what happens is you're out of the channel on a plane no problem, then you slow down come off a plane and oops the water is too shallow and your lower unit /prop hits being the lowest part of the boat.

Hitting a rock might bend your prop and you might need to replace, many carry a spare prop on board as it can be replaced relatively easy even out on the water with an outboard.

That same situation with a foil boat would be disastrous, again just one very expensive and dangerous mistake.

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