Launch HN: OutSail (YC W23) – Wingsails to reduce cargo ship fuel consumption
Sails powered ships for millennia; but then the convenience of energy-dense fuels displaced sails. As ship speeds eventually exceeded wind speeds, the consensus became that sails had no place in shipping and were relegated to hobbyists and sport. Fast forward a century and a half, and maritime shipping, like all other industries, is facing a reckoning to mitigate the greenhouse gasses produced by their activities.
The International Maritime Organization (IMO) has introduced new regulations which use a vessel’s Carbon Intensity Indicator (CII) to grade ships. This grading scale becomes more aggressive over time, and any ship with a poor grade must take corrective action. The corrective actions can be as non-invasive as reducing speed (aka: slow steaming) or as extreme as a retrofit to use a different, cleaner fuel source. This costs millions and takes a ship out of commission for months, and it’s difficult to ensure your (now more expensive) fuel is available at every port of call. Ship owners are hedging their bets that slow steaming will dominate their future, with ship order books full to reflect the increased capacity needed when containers take 20% longer to cross the ocean.
Or option three. There is sufficient wind on the ocean to power the entire shipping industry, if you’re willing to grab it. Wind Assisted Ship Propulsion (WASP) devices can be used as a corrective action to improve a vessel’s CII rating, without reducing ship speed or changing the route. In other words, a return of sails.
We are hardware engineers with over two decades of experience between us, working at Tesla, SpaceX, JPL, Relativity, and some startups. The idea for OutSail came from Arpan and Joseph getting coffee after work one day. When we asked each other “What would you do if you weren’t building satellites?” maritime cargo came up from both sides; Arpan from having studied the industry for opportunities to reduce emissions, and Joseph from a love of hydrodynamics and maybe too many sea-shanties. Bailey and Arpan, meanwhile, had been looking at working on bicycling infrastructure. What brought the three of us together was actually a Dungeons & Dragons game where we realized we made a good team! We settled on OutSail as a good fit for our hardware hacking mentality, trading in our druids staffs for spanners.
Aerodynamically, sails are simply vertical wings. Wind blowing across the vessel causes the sail to generate lift and drag, and the resultant vector has some forward component to pull the ship through the water. However, if the wind comes from an angle too close to the direction of travel, there is no thrust. As an added complication, the sail only sees the relative wind. If the ship travels faster, the wind will appear to come from closer and closer to the direction of travel, even if the true wind is coming from perpendicular to your course! Despite this, standard sails can still produce forward thrust as long as the wind is at least 20 degrees off from directly in front of the vessel. This is how our sails can still save power, even on a fast moving vessel.
There are many sail technologies out there. A common question we get asked is “Are you going to use flettner rotors/suction airfoils?”. Both of these technologies use power supplied by the ship to increase the lift ...
279 comments
[ 21.7 ms ] story [ 6274 ms ] threadJust like some strong pressure will bend a tape measure - will a strong wind gust damage your sails?
I also was kind of expecting a kite TBH. I wonder if the extra work of a kite is a good trade off, I feel like the tying off the thrust issue is easier with a kite than a mast.
Edit: I see wingsail in the title and I think it’s slightly ambiguous. I want to say this is “mast” based? Not a tech issue but
Regarding kites, we looked at those quite a bit. The challenge with those is that kites tend to be best for when the wind is coming from behind you or crosswind. For a container ship traveling at high speed, the kites would act more as a parachute and slow you down (even if you were extracting energy from them).
Have you considered the effect your design has on the drift and drift angle of a vessel yet? Looks like your aiming to benefit from conventional sail assisted lift but there is a thin line between lift and drift. The negative effect of drift induces increased consumption so some kind of trimming needs to be done quite fast to maintain lift effect. To maintain an optimal angle of attack to get the maximum lift requires quite fast adjustments which on sailboats can be done in two ways, either by trimming sails or adjusting course. Adjusting course on large cargo vessels takes quite a while so i don't see that as an option unless the sail is hooked up to a fast acting autopilot.
https://www.airseas.com/seawing
And they seem to make more sense than sails.
> SkySails is the pioneer of wind-assisted ship propulsion systems based on kites. The technology was successfully proven on board of sea-going vessels between 2004 and 2012. However, in order to make the biggest possible impact on the ongoing energy transition, SkySails decided to focus on the dynamic energy sector with its SkySails airborne wind energy systems for power production for the time being.
> The SkySails propulsion system for vessels is therefore currently not marketed anymore.
https://skysails-marine.com/ | https://skysails-power.com
Back in the days they even had some commercial orders: https://www.surfertoday.com/kiteboarding/norwegian-ship-orde...
Not sure I buy their reasoning of discontinuing the shipping angle. Seems likely it was a hard sell.
I always though it seems like a cool idea, given that the automatic controls were robust enough. Hope airseas have more luck.
But https://skysails.com have completely given up on ships (full focus on stationary electricity generation), and they had already been at the point of operating an installation on a real life freighter. But at least it's not clear that their goodbye to ships was due to technological challenges: it might be because of unrelated business events, e.g. the shipping company they partnered with was already on the course to failure (chances are from their perspective the kite project has been a desperate hail mary from the start), and are some point the not-electricity part had mostly pivoted to shopping management software and that part was eventually completely separated from anything kite related.
America’s Cup AC55 yachts come to mind with an unstayed carbon fiber wing. As do friendship sloop two masters.
Even if this proposed mast is stepped through the entire container, the forces on it will be plenty to cause issues since the containers are only held down by neighbouring containers and the 4 anchoring twistlocks. This proposed design will 100% require standing rigging to support it - the claim that the rig will only experience 10s of kn of loading is almost certainly incorrect as well - 30ft racing sailboats will experience loads exceeding that at the chainplates regularly. The moments about a mast are huge, even on relatively small rigs.
Have you done any weather routing calcs to see what the angle of attack for the big ship lanes? Perhaps an integrated trip cost-benefit?
Also, you might not want to use the WASP acronym and stick with just "wind-assisted propulsion". The wind industry will immediately think of the WAsP software [0].
[0] https://www.wasp.dk/
Bailey has written a routing software which we use to send virtual ships on crossings (for instance Trans Pacific), incorporating historical weather data. Even with no change in route or vessel speed, we can see benefits.
Yikes. Containers are stacked as high as they can be to not crush the containers below. Applying additional downward force is going to cause cascading failures.
You've also just limited your deployment to routes that have double-stack container cranes, which AFAIK aren't that widely deployed.
Have you guys actually talked to anyone in the shipping industry or visited a cargo shipyard yet?
Also, sails apply lift, so upwards pull. I know nothing about sail physics, but this claim is in the OP.
Since port stays are very costly, you won't deploy this for anything shorter than a transatlantic voyage anyways. So the double-wide setup seems less of an issue.
Their sail might provide some lift, true, but they also apply rotation and shearing forces around the (double) container like a lever.
See here [0]: "The MAIB’s preliminary assessment found that [the ship]’s violent pitching and ploughing into the heavy seas resulted in a rapid loss of speed and heading control, which exposed the deck cargo to green sea forces capable of overwhelming the maximum loading of the container securing arrangements... corrosion to the vessel’s deck cargo securing arrangements may have contributed to the scale of the loss."
Or here [1]: "At 0800, the ship sailed from Xiamen with 6,466 containers on board... At about 1000, the bosun and four deck crew mustered at the forward end of the weather deck and began a post-departure inspection of the deck cargo securing arrangements... they checked that the manual twistlocks, connecting the first tier of containers to the hatch covers, were locked, and ensured that the container lashing rods were correctly tensioned. With over 12,000 twistlocks and 3000 lashings to inspect, the checks continued all day"
[0]:https://www.gov.uk/maib-reports/loss-of-34-containers-overbo...
[1]: https://www.gov.uk/maib-reports/loss-of-cargo-containers-ove...
I think they must have said they stay put is under weight and the lashings just keep them from slipping? Who knows, I'm definitely wrong here.
Love how this idea has energized HN.
Our design evolved out of a routing/performance analysis software that we run on historical weather data. Angle of attack and trip cost-benefit varies per lane. In general transpacific and transatlantic have amazing winds, with other routes performing well but not at well.
We've done the excel-level analyses on container loads and wing buckling forces. It all checks out. There is a combined-load case at 15deg of roll with heavy containers and heavy winds that's zero-margin, but as you said we can reef when required. Reefing will likely be single-digit minutes, but we can also feather (0 angle of attack) much more quickly.
1) what size container ship are you targeting?
2) how many container sails are needed in an array to achieve 20% fuel cost reduction?
3) what scale of retrofitting is required to install this onto existing fleets?
4) what sort of training is required for existing staff to properly trim the sails / will this impact headcount requirements per ship?
2.We will need 15 sails to save 20% fuel on a 4000 TEU vessel travelling transpacific or transatlantic.
3.We will install an override panel on the bridge of the ship, a lidar system to sense wind gusts and some extra lashings will be tied from the sail’s container to the containers below it – that’s it! None of those additions will require permanent changes to the ship.
4.No extra staff will be needed, our sails will be controlled autonomously. However, the captain will be given controls in the bridge if they ever want to force the sails to retract.
Why steel? Durability I assume? Have you modeled using a textile?
Do you have load sensors throughout the wing? Anemometors?
How active is the trimming? Is it just a single axis of rotation or do you have the ability to adjust the leech and luff shape? If so do you have the ability to adjust both the leeward and windward skins? Or just the windward? 2mm steel seems like it has a decent amount of play at that scale? Have you built any bigger scale models with steel? Feels to me like iteration time would take a significant hit playing with steel instead of cloth?
As consistent as these ships are with their speed under motor, the apparent wind will be all over the place. Could see apparent from 50+ on the nose to 5 knots from dead astern. Do you intend to have a fixed set of optimal wind velocities and trim settings? Or want to make something that is usable and automatic in anything but the most violent of breezes?
How much of the bill-of-materials is custom and how much is off-the-shelf type components and structural bits? Any custom composite parts or fairly off the shelf steel tubing, bar, and such?
Also are you hiring?
For load sensors, we're thinking strain gauges and pressure sensors to measure wing surface pressure and use that for live feedback. Anemometers might be mounted on the top of the wing, but more likely we'll use a master anemometer at the bridge to send info to the entire array.
For the wing shape, we're currently looking at a symmetric airfoil with fixed ribs inside for strength, so not able to actively change the camber, but we are looking at the ability to do wing warping to change the overall shape of the wing. We are still working to get our first data from on the water, so no good answers on the trim other than we want to make this as automatic and turnkey for the ship master as possible. We're quite early in the design still, though, so don't yet know where the limits of the technology are. Likewise, no answers on BOM and sourcing for you. However, we do plan to start hiring after our seed raise, so feel free to contact us through our website!
I'd imagine the last 1-2 generations of America's Cup boats would have a lot to glean in terms of wing sail camber changes and how they operate. Pretty neat to watch how they use flaps vertically, but there's a lot of hydraulics and carbon at play there as well.
Maybe the competition is these guys? (Inflatable sails) https://www.michelin.com/en/press-releases/michelin-continue...
And something a bit more conventional off the bow when winds are favorable? https://skysails-marine.com/
On top of that, higher altitudes wind Jane more power potential than the ones used by sails, ask kytesurfers !
Despite the switch from wings back to "normal sails" In my view, this latest generation of America's Cup is especially awesome from a follower's perspective for two distinct reasons.
1. The rule is similar to last gen, a foiling 75 foot monohull. A number of the initial engineering work and sorta figuring out how to design and build the various systems has already been done, a team wanting to join in on the fun doesn't have to reinvent the wheel with everything unless they believe they can have an edge by doing so. There are old boats for sale as well as a 40-foot model for training the athletes on their controls.
2. There's a centralized repository for reconnaissance. Meaning, every team, and some of the media have access to sailing, launching, and training footage of every team. What has for over a century required each team employ their own multi-national team of spies to surveil each competitor. It was unnecessarily costly and the fans get the added benefit of being to watch much more of each team's boats as their systems morph throughout the design process. I have a friend on the recon team and as well have been exposed through a yt channel, "Mozzy Sails"[1], who does a great assessment on the various teams systems developments.
If you're a fan of F1 for the engineering bits, you'll likely feel right at home following some of the America's Cup coverage. Even the technical documents like the Class Rule and super interesting to me. [2]
[1] https://www.youtube.com/channel/UCK0h2Yj6jcyeXGeITonYnOA [2] https://www.americascup.com/files/m5498_AC75-Class-Rule-v20....
Hope you the best and any if there's chance you need a hand in Barcelona, I'd drop everything for a shot to work on a campaign.
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> For load sensors, we're thinking strain gauges and pressure sensors
"We're looking"? "We're thinking"? Considering your demo video was a guy showing off folded printer paper secured with duct tape, and a gauzy fabric built around an off-the-shelf tape measure....
How far along are you? Sounds like you're nowhere even near a prototype, let alone a beta design. I know every company has gone through a design phase and a (sometimes lengthy) build up... but you don't usually see them start the PR hype train before they've even got a CGI demo or a model that isn't made out of scrap. What is it that makes you a real company, and not just some guy who got real excited about an idea he had last week?
And YC would be betting that their experience counts for something beyond just a random person with a weekly idea:
"We are hardware engineers with over two decades of experience between us, working at Tesla, SpaceX, JPL, Relativity, and some startups."
The experience you listed read more like name-dropping PR to sell this whole thing to other investors down the line.
Will there be a keel or any other foils to help create lift to not just get blown sideways?
To me this seems like solar roofs on electric cars. An obviously good idea that doesn’t really have a meaningful benefit.
The various supplemental sail technologies being tried to improve merchant shipping fuel efficiency are mostly only effective going downwind. They have to make serious design compromises compared to a dedicated sailing rig in order to meet cost and space constraints. But with the cost of fossil fuels expected to continue increasing (eventually including perhaps some sort of carbon tax or emissions cap) even a minor increase in efficiency is worth pursuing.
My guess is that some sort of deployable kite sail will eventually win out instead of this wingsail concept. We'll probably start to see that integrated into new ship designs as the cost is pretty low and the equipment occupies a fairly small volume at the bow.
This is a very cool, very hard idea to execute - i shudder to think at the kind of testing, reliability and certification you need to ensure a foldable ten-storey building is safe around human crew in gale force winds. It's a moon shot, and sometimes these take you on the Moon.
Nitpick: you seem to have a typo under "Safe": it says "safely and secularly" which I'm fairly sure should be "securely".
Godspeed!
Yes, I am fishing for ideas!
https://www.realclearscience.com/quick_and_clear_science/201...
I thought this was a fun article: https://www.elidourado.com/p/cargo-airships
https://www.businessinsider.com/foldable-shipping-containers...
That's yet another idea that people often think of when people wonder about improvements for container shipping. The container shipping company I worked for studied it every few years. There's various reason why it hasn't been done. It's not just the container or the container vessel. It would be good to reach out to the right people and see what the problems were that prevented this from being used. It wasn't about making a container collapsible, it was stuff surrounding that.
There are sometimes some really nice cost saving projects that were pretty innovative. Plus maybe also easy if someone thought of it. But often it required a bit more knowledge to think of than "add sails" or "collapsible container".
One fun thing what a few shipping companies many years ago is to take existing vessels and make them bigger. So really cutting various parts of the steel and adding more (e.g. height). An random Google example (use retrofit as search term): https://gcaptain.com/upgrades-to-famous-maersk-e-class-to-bo...
Innovation is coming, but the labor unions are apprehensive. We have literally heard them say that they don't fear automation and innovation, but "put a steering wheel on it." That's such a short sided perspective and if it doesn't change soon, we're going to see a very crippled industry being outsourced by international companies.
For example, there is market for shipping containers along the West Coast. Most of the inter-US shipping goes by rail but sea would make sense for some of it. Small container ships would be perfect and locally built would make sense.
Ships for the US Navy (including the Military Sealift Command) are also built in the US. So, shipbuilding hasn't stopped, but the US's comparative advantage is not really in shipbuilding.
https://en.wikipedia.org/wiki/Fuel_oil#Health_impacts
https://www.cruiselawnews.com/2010/05/articles/pollution/rea...
https://www.imo.org/en/MediaCentre/PressBriefings/pages/03-1...
Also, there's something about the animations in your demo video that reminds me of a Dahir Insaat video.
Also, hahaha, just looked up Dahir Insaat, thank you I guess?!
1: https://www.rivieramm.com/news-content-hub/sea-cargo-ro-ro-w...
This feels like something that the govt should be subsidizing through grants.
Also, what is the maintenance like on these? When I was in the Navy we had huge crews to conduct routine maintenance but on cargo ships, there tend to be small numbers.
Love this - what a cool idea!
Container vessels are designed to sail at a very specific draught. The bulbous bows on most container vessels are fine tuned hydrodynamic shapes that impact ths wave patterns that ships generate. Sailing at a different draught because you're adding ballast will greatly decrease fuel efficiency. Additionally any added draught also increases the amount of water you have to displace, so again decreasing fuel efficiency.
Further more, I highly doubt regulations would permiss this. I'd have to dive in IMO statues to verify, but imagine because of any event the rolling moment from the sails decreases in a short amount of time. Now the vessel has the same instability that you initially tried to offset, just caused by your own ballast.
I'd be interested to hear what your thoughts are on these issues. Non the less, very interesting ideas
https://alsum.co/wp-content/uploads/2021/04/Perdida-de-conte...
Look at a purpose-built sailship from the age of sail in a north Atlantic storm. It is a rough ride.
https://www.youtube.com/watch?v=Y7RABaByP_8
Another attempt in a similar fashion is the Oceanbird concept by Wallenius Wilhelmsen, but that means building the vessel from the ground to handle the forces and that over-head loading and unloading is not possible, thus the aim at RO-RO ships.
https://www.theoceanbird.com/
With one vessel already ordered:
https://www.walleniuswilhelmsen.com/news-and-insights/highli...
Personally, as a commercial sailor and software engineer, this container approach screams of VCs throwing money at commercial shipping without understanding the industry. Profit margins are non-existent and are already hugely optimized with possibilities for specialized solutions. This wing sail will have to compete with synthetic fuels without increasing the cost due to crewing requirements.
Oceanbird is awesome! The trouble is that overhauling the entire industry with new-built ships would take too long to make a meaningful climate impact, and be extremely expensive (not to mention that their approach only works for ro-ros).
Synthetic fuels will compete with aviation for the green hydrogen supply (needed to make methanol/ammonia/green hydrocarbons) and are expected to cost 2-3x what current fuels cost. This net makes our fuel cost savings case even stronger.
Industry insiders generally already know that there's really no good cost-saving decarbonization solution, and that decarbonizing fast is a hair-on-fire problem for owner/operators. The barriers standing in the way of most wind-assist devices are: poor ROI, shipyard availability for retrofits, risk to shipwoner (capital upfront), and that they don't package on containerships. We solve all these problems by using a large, efficient wing and depending on the container load path. There are technical problems to solve, but the fundamental physics works.
Have you actually talked to anyone in the cargo ship industry about your idea?
If the sail is pulling, the container below would see a remaining uneven load from above. Is there a limit to this? Loading/unloading an unbalaned container sounds like a problem, but is it, while sitting on the ship?
A small to medium vessel fully loaded is like 150.000 tons. 10% of that is 15000 tons, imagine the force that needs to be transferred to the structure of the ship in a place where it was not designed to handle that force.
I worked in the container shipping industry. It doesn't sound like this person ever talked to anyone in the industry. It's not like "add a sail" hasn't been thought off loads of times before. I've seen a few times where people spend 6 months to run a project where they never talked to a person with experience. Then that project would eventually fail. Circumstances and restrictions sometimes change over time, so trying to solve the same thing every few years is a good thing. But "sail in a container", ehh..
The typical problem with containers is non-standard or unsecured cargo pressing against the side walls, which are indeed very weak.
Shipping is responsible for like 2% of emissions. A 5-10-20% reduction on a small number of vessels for a small number of voyages is not gonna make a dent.
You would fold these down rather than trying to ride out a swell with them up. They go out of they way to clarify how easily these can be furled and unfurled.
Being fair, this is really broad and doesn't mean much at all.
Just like a jetliner wing that can be folded up. On the plus side, jetliners regularly hit speeds relative to the air that are ten times as fast
They claim a save of 400kW per sail, with a boat cruising at 22kts. Let's do some math:
- 400kW is 400e6 J/s, or 400e6 N.m/s
- 22kts is 11.31m/s
So the forward force must be 400e6/11.31 = 3.5e7N, so around 3500 metric tons of force for a single sail. And with a relative wind coming from the front usually, this means the side force will be much bigger than that.
I am calling this BS
(Assuming a fuel price of $550 per metric ton, the cost of fuel for a trip from China to USA would be around $1,485,000 (2,700 metric tons * $550))