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Comment by rustyconover | Hacker News Reader

What if a slow moving sailboat came across this plane’s path? If it is using ground effect it couldn’t climb much.

The ground effect vehicle goes around the sailboat in most circumstances.

There are rules of the sea that dictate who has right of way when passing in given directions. And there are rules they apply to vehicles of differing maneuverability.

A sailboat wins over most boats (except extremely large ships or ships doing work - fishing, tending buoys, etc).

It’s not a big deal. If the sailboat is crossing paths with this, it just tweaks direction to the stern of the sailing vessel. If they’re heading straight at each other, they pass port-to-port (left to left).

There are rules of the road for seafaring which apply even to these types of craft. A sailboat usually wins over a powered craft.

so if a sailboat suddenly veers into the path of this thing, what is it going to do? Collide or ditch

"GEVs may be unable to climb over or turn sharply enough to avoid collisions, while drastic, low-level maneuvers risk contact with solid or water hazards beneath. Aircraft can climb over most obstacles, but GEVs are more limited. "

Realistically these things aren't going to be operated in-flight anywhere close to the proximity of other craft. They'll motor from dock out to a predefined and clear[able] "runway". Once you're clear of a port most stretches of open water are mostly empty (even those within sight of shore) -- it should definitely be possible to plot "cruising-altitude" courses that never place you within (N) of a hazard. And if there is ever any uncertainty or doubt about incoming situations you can always drop down to a safer mode to chart a new course.

No. All of the major ferry routes they are proposing to serve already have a significant amount of vessel traffic. Seaglider operators will have to obey the rules of the road to avoid collisions just like any other boat.

Kind of a mix of both really.

Anywhere near significant boat traffic (e.g. in harbors), we'll be on our hydrofoils at speeds of 20-50 mph. So in these environments, we're just another boat (albeit a very comfortable, wave tolerant one)

We dont leave the foil to takeoff onto our wings until we leave the harbor. This doesnt need to happen on "runways" though. We'll already be at takeoff speed (~50mph) as we're leaving the harbor, so we really just jump out of the water whenever we choose to. This way we dont need to clear long stretches of water for a "runway", which has limited seaplane operations.

Absolutely agree: Seaglider operators will have to obey the rules of the road to avoid collisions just like any other boat. WIGs are actually already in the COLREGS (we're last in line for right of way, but on the list!), and our sensor systems will ensure that seaglider captains have excellent situational awareness.

I try to be positive about everything, but this entire idea is terrifying as someone who spends time on the water.

I highly doubt your pilot can spot a small fishing vessel or a kayak going over 100 mph.

Bro no. Lol. There will be boats there.

In your theoretical, why is this thing flying so close to a sailboat that the sailboat can "suddenly veer" into its path in first place? The average non-racing sailboat has a top speed of only about 8 mph.

a 45-foot pleasure catamaran can do 80-90% of the true wind speed. 15-20 knots is not impossible.

anyway, if it is possible that a GEV can collide with a sailboat, it will happen eventually

Very very unlikely

Same thing as when a "sailboat" suddenly veers into the path of a heavy cargo ship. The rules of the sea are that steam gives way to sail, but physics puts obvious limits on that.

The law of gross tonnage is in fact derived from classical Newtonian physics.

Can't remember if they're considered "working vessels" over a sailboat, which would make them the stand-on vessel based on maneuverability anyway, but it's just silly to get in their way in the same way that it's silly to dawdle across train tracks.

Boats can't fly over things either. You crash or follow the rules and avoid.

Hang out on Lake Union sometime in the summer. Boats everywhere, and seaplanes everywhere dodging them while they land and take off.

Near as I can tell as a boat driver your job is to stay very, very predictable while the planes weave around everything. Those pilots are good. ;)

It's pretty fun for people to see a float plane zipping by at 80mph, 20 feet away, while it's taking off.

It's nearly impossible to create a ground effect vehicle that can't fly out of ground effect for a limited time.

They need a significant amount of extra power to get out of the water in the first place, so there will always be more power available to climb out of ground effect.

The maximum altitude would be limited, you wouldn't be able to climb over a mountain, or over clouds. Depends on the exact specs, but should be more than enough to clear large ships, or at least get the altitude to make it safe to do a steep turn.

The vehicle is limited to ground effect due to regulatory limitations and because it provides efficiency benefits but not physically. There are different classifications of WIGs, class B allows for hops over things so this could be a future option. In reality a sailboat is a pretty easy thing to avoid. Since its basically flat on the water, there aren't many large obstructions to line of sight and something like a sailboat is moving much slower relative to seagliders. It will be a simple “see and avoid” maneuver with ample time to react!

To be clear, seagliders are limited to ground effect in that it is physically impossible for the captain to remove the vehicle from ground effect. The flight control system locks the vehicle to within a wingspan of the surface.

What would happen aerodynamically if your vehicles got out of ground effect? Would they stall pretty much immediately?

Either recreational boating has to be eliminated or your thing will never work.

180mph is insanely fast on the water. A sailboat even as big as it is will be hard to spot.

Also, related to sailing or boating near this craft, the noise level must be quite substantial. At least not comparable to passing other boats

I imagine you'd just go around it.

It cannot sustain flight above the GE altitude. Presumably it can bounce a bit.

good point - a collision with an obstacle would probably be as fatal as plane taking off colliding with something.

This is bound to happen and can't really be controlled.

Realistically you'll see that sailboat in advance.

At 100+mph?

My sailboat uses radar, I can see things from a good distance away. Let's say 30NM. Surely the plane will do better. But let's say it's going 180mph, or ~160kts. That's 11min from first radar contact to collision. With all that forewarning, avoiding a yacht isn't a big deal. If they can't avoid it, they can stop with 11min warning.

Let's say visual only. There will be restrictions on visibility for visual flight rules. So say that they can only fly with more than 10NM of visibility. That's still 3m45s to take action. Surely enough.

Just for others here, this is very misleading:

1) Sailboats (even moderately sized ones) often do not show on radar at all.

2) 30nm is probably way too optimistic, at a height of 50ft your line of sight is only about 8-9nm. Radar is LOS.

3) 11m is a terrifyingly short time, even if this was all correct

4) you can't identify things based on radar alone, and there's no way you can make out what something is even at 5nm.

5) there's no way you can see a boat at 10nm lol

> 11m is a terrifyingly short time, even if this was all correct

Is it? How much warning do you get when a car brakes in front of you on the highway?

In 11m you could write a report on how to avoid the collision prior to actually performing the maneuver

Cars have lanes etc.. it's very different on the water. Hard to tell often if someone is going to hit you or not. Distances are nearly impossible to judge.

Yes we'll have several sensor systems onboard that augments the captains visual perception, including radar, AIS, and we're looking into computer vision systems as well.

We've been testing these sensor suites in helicopters today. Flying <50 ft off the water at speeds in excess of 100 mph, simulating the seaglider operating conditions. We have plenty of time to detect and avoid traffic even in crowded waterways at speed.

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