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Comment by thatcherc | Hacker News Reader

This looks like a lot of fun, but I'm wary of its safety. Foiling boats (at least the sailboats) have a tendency to come down hard off the foils if not sailed exactly right. That's why you'll see helmets worn by sailors both on big foiling AC72s and F50s as well as a the single-handed Wazsps, Moths, and UFOs.

The deep V profile the Candela's bow looks like it would handle dropping off the foil or hitting a big wave pretty well, and the 100 Hz foil control loop is reassuring, but my experience on little foiling sailboats would keep me cautious on one of these for a while. However, getting a boat to pop out above the waves is such an amazing feeling that I'd take a ride on one of these in a heartbeat (just maybe with a helmet!).

Some foiling sailboat crashes for reference -

- https://youtu.be/875yq0-ogwo?t=20

- https://youtu.be/frAkDEszgZc?t=26

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You hit the nail on the head here. Safety is a key question that often comes up in discussions that we have with customers, and is of course a key focus in the development of the Candela model range.

As you mention, the deep V hull cuts waves pretty well, but we also have algorithms monitoring the position of the boat in 3D space, looking for signals that indicate a treacherous seastate or an unfavorable position of the boat. This means that we won't do the nose dives that you see in the sailing videos.

Be sure that we have landed unexpectedly quite a few times to get to where we are! :D

To sum it up, when you are accustomed to flying with the Seven and you know where the limits are in terms of wave handling, then it's no different from riding in a regular boat in choppy seas or high waves. Unruly seas require alert sailors, in all types of boats.

We're publishing a short video soon, purely focused on running through waves from large passenger ferries. Sub to our youtube to know when.

What are the limits in terms of wave handling? How well does it stack up to a large rib in rough seas?

Open waters on a windy day or the day after a windy day can be hard.

Check out our videos from the Caribbean and a comparison with an 8 meter aluminum boat in a choppy archipelago condition.

Can we foil in every single wave height there is? Abosolutely not, but our boats outperform regular boats in comfort in weathers where you'd normally bring out your 8 meter daycruiser/open boat.

It's also worth remembering that in rough seas, you can go down from the foils with no issue. You just cut the efficiency down to regular boat levels...

Love your guys work. Do you have any thoughts on making something work for really rough seas? I want to make an electric boat suitable for Hawaii.

Hi, that's a really interesting boat concept.

Even if not foiling, can you still take the boat out with, say, beaufort 8-9 weather? That's more similar to what I was expecting in the "high waves" videos, and is not unusual to encounter when commuting or spending the day elsewhere, depending on your area (obviously, it starts being unpleasant if you want to spend the day at sea on a speedboat).

Edit: now realizing it, but your target market is probably only going to go out with calm weather in protected seas, given the price point and finish. I hope that sort of product will get mainstream at some point.

Let's just be honest, you're not going out in Beaufort 8-9 kind of weather with this size boat, foiling or not, unless you have to. I have a boat larger and likely more capable of taking on rough seas than the Candela and I will avoid those kinds of winds if I can, and only really go out in that kind s of weather if I must.

40 knots is already nasty on cruise ship. In this size boat you'd be praying to get home alive, let alone undamaged.

Yeah, you are right, I was mainly thinking about swell, which can sometimes be quite important, while local wind isn't particularly strong. Beaufort scale is more a wind scale than a swell scale, my apologies for using it. I don't think big waves are that problematic to navigate with a speedboat if the period between two waves is long enough, but I don't think foiling would work with that kind of sea. Since I used to live in an area where such conditions were relatively frequent, I was wondering how well the Candela could handle them.

My boating skills aren't that fresh anymore, despite living on one during my childhood, and spending a good chunk of my youth close to the sea. I might thus misremember or exaggerate things, but I am fairly confident of the above.

You're not wrong, but also the minimum foiling speed for this particular boat is listed at 17 knots. If you're navigating a speed boat through rough seas at 17 knots you're a braver person than I am for sure. :o)

Below that it seems to me like it behaves more or less like a regular boat. Regardless, I'd probably avoid speeds above 10 knots if I found myself in relatively high seas, and I'd just avoid going out in that kind of boat altogether if I had the option. If you do find yourself in that kind of sea though my experience is that most swells tend to come from one direction so you can find a good bearing surf the waves, zig-zagging if need be. Adjusting speed as need be is crucial in rough seas for sure.

It does have a reasonable draft without the foils extended it seems, 1 meter, and at 2.4 meters wide it seems like it could be pretty stable actually. It'll be interesting to see once my buddy gets his delivered.

If you encounter force 8-9 while out on a speedboat day trip you've seriously messed up with your preparation and planning! it doesn't just come out of nowhere.

The reality is that it's the sea state that matters. A sheltered lake or estuary could only have 30cm waves with 40 knots of wind, whereas the open sea would have a 1.5m+ swell with 1m waves on top.

So can it go in the ocean?

I'm sure given my other comments in this thread you can figure out which customer of yours is my friend. We're on the Swedish west coast where the sea is quite choppy most of the time, so it'll be really interesting to see how well it performs. Happy to provide you with feedback as best I can.

So essentially you implemented "Glide-by-Wire" for boats?

( https://en.wikipedia.org/wiki/Fly-by-wire )

Looks like fun...in the right environment. For example, our local lakes have vegetation that comes all the way up to the surface. Hit a "kelp" bank at speed and it will not end well. I've had the experience of getting stuck in one such beds in a rowing shell. Let's just say it wasn't fun at all.

Open water with a low probability of colliding with anything near the surface? Yeah, this looks like a blast!

I can let you know how it performs in a couple of weeks – a buddy of mine ordered one of these before the summer and it's due to be delivered tomorrow. Rest assured I'll take every opportunity to tag along, especially since I'm looking at a lot of spare time on account of COVID-19 making my job redundant in a week or so. :o)

Do you have a ballpark idea of the price?

I know it was around or north of $250k, but I don't know the exact figure. I'll ask tomorrow or this weekend.

Are you in Europe?

Yes.

Following

I have some experience with foiling sailboats, and I would never expect the problems that foiling sailboats have to impact motorboats at all. Control problems are all well solved for motorboats, but the moment of a sail that is perpendicular to the direction of travel puts a huge kink in the picture that has been hard to tame. Even then, there have been huge strides lately...like the iFly 15, which uses a mechanical active controller which basically relies on two small rods with a float on the ends to measure foiling height and heeling, and mechanically adjust the coils to maintain stability. It works marvellously.

I recently picked up a foil board to go with my other windsurf gear, and the sail is absolutely a confounding effect

I've read some on the subject, and got a book by a famous boat designer, Kotaro Horiuchi, which describes the actions of the float controllers you are talking about as well as other aspects. Foil boats have to be fairly lightweight at the moment, which is why the america's cup boats are designed the way they are.

I've also seen those e-foil surfboards but have never tried them as the price point seems absurd.

My board (and all the foils I see on surf gear) just have enhanced static stability based on some combination of dihedral, a fuselage, and a negative lift rear wing, very similar to an airplane. That's because it's down to a shift of body weight, sailing forces, etc.

It's become all the rage in the last 2-3 years with things still not quite standardized. I had to drill out my foil-approved board to get larger M10 bolts in there.

There's a whole community of DIYers building e-foil boards at https://efoil.builders/. I haven't actually built one because I don't think I would ride it enough to justify the cost.

I do lurk on that forum and check out the projects people are making, there's a lot of really cool work done to 3d print propellers and other structural parts and bring the cost of manufacturing down. Between rapid prototyping and chinese BLDCs / ESCs, small electric vehicles like e-foils are actually reasonably priced to build yourself.

This is awesome - thanks for sharing! The commercial efoils have caught my eye but they're definitely outside my price range. Cool to see that you can get a efoil and a fun project a lower cost

Of course, once you buy the 3d printer, filament, metal cutting supplies, various epoxies and waterproofing sealants, cabling, soldering tools, and nuts and bolts...

Wow, looks like you can eat it pretty good on one of those sailboats. But.. a motorboat wouldn't have the same issues, would it? Consistent propulsion, and not having to deal with wind force on a mast?

That's part of the fun! For smaller ones like the Moth or Waszp anyway. Less fun and quite expensive in an AC75...

The dynamics of a sailing boat are far more complex than a motor boat. The drive comes from halfway up a huge lever (the mast) over the foils and its position relative to the forces produced by the foils is constantly and suddenly changing both on its own due to gusts and shifts in the wind and also caused by the sailor's inputs.

A motor boat pretty much only has to deal with going up and down over the waves.

It's like the difference between solving a linear equation and a higher order differential equation.

They do cover this in their FAQ.

If you are used to it, landing unexpectedly is quite undramatic. This can happen if you foil at the lowest speed limit, or if you attempt to cross a wake or seastate that is beyond the capabilities of the boat, which is approximately 1 meter of wave height.

Water is fairly forgiving when landing unexpectedly at the speed at which the Candela Seven can operate, although you might get a bit wet.

Foiling sailboats are crashing because of sail: their propelling vector is too high above sea level, which causes side or bow capsizing in split seconds. Motor boats has totally different physics, they rather take off, because they have heavy stern with engines and lightweight bow. If you put battery in front of vessel - it will perform even better.

Those crashes look about the same as what I've seen on catamarans (Nacra F18), or on single hull dinghies with trapezes, particularly when flying a spinnaker. That being said, not sure if adding the excitement of possibly capsizing hard to a powerboat would be a huge selling point for me...

I thought the same until I started sailing a UFO. You are going way faster than any cat or dinghies. Everything happens substantially faster and the water feels like pavement when you hit.

I don't think you have the same risk of stalling a powerboat foil like you would on a sailboat. You have much more predictable power at your disposal and something like a sharp header is irrelevant.

What about the Soviet Raketa boats?

Unreliable and very thirsty and not really foiling, just slightly over water.

Have you seen Boundary Layer Technologies? You should eat their lunch, they certainly could use more competition.

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