Tech
This is how two contra-rotating propellers can make ships more energy efficient
By using two propellers that rotate in opposite directions, a ship can use less energy to move forward. New knowledge means that more ships can use the technology, including Hurtigruten’s Sea Zero project for its coastal cruise ships.
SINTEF has now designed and manufactured new measuring equipment for model testing of contra-rotating propellers. This could be good news for many large ships.
“We see that propulsion efficiency increases when we utilize some of the energy lost from the front propeller at the same time as the rear propeller gets better water flow. This can provide more than 10% better efficiency compared to conventional propellers,” says Øyvind Rabliås, a researcher at SINTEF.
Although contra-rotating propellers are not new, they are still rarely used on commercial ships. The reason has been their cost and more complicated design than traditional layouts. That may be changing now.
“Together with our research partners, we’ve spent a lot of time on understanding and developing solutions for this. Now we believe that the technology is mature and ready for wider use,” says Jahn Terje Johannessen. He is a senior hydrodynamicist at Brunvoll, a leading provider of propulsion and maneuvering systems.
Good test results
SINTEF’s new measurement system was developed when Hurtigruten decided to use contra-rotating propellers for its zero-emission cruise ship in the Sea Zero project. The goal is an emission-free Hurtigruten ship with a sustainable and circular solution by 2030.
Contra-rotating propellers have significantly better efficiency than today’s propeller systems.
“This design simply means that we need less energy to achieve the same speed compared to conventional propellers. Brunvoll’s design is also more efficient than the contra-rotating propellers that exist today,” says Gerry Larsson-Fedde, chief operating officer at Hurtigruten.
From drawing board to reality
A broad interdisciplinary team at SINTEF Ocean, from technicians and instrumentation engineers to design experts and researchers, has developed the new measuring equipment for model testing contra-rotating propellers. Together, they arrived at a solution that is well suited for self-propulsion tests.
Two dynamometers, which are instruments used to measure force in rotating systems, have also been developed.
“One version is suitable for integrating into ship models that are tested in the Towing Tank, meaning that it is built into the model, and the other version is used in open water tests and in cavitation tests,” says Rabliås.
The system has already tested Brunvoll’s propeller system for Hurtigruten. The results provided valuable insight into the system’s performance and helped identify the most efficient propulsion solution for further development.
“It was an added bonus for Brunvoll that the project is so versatile. We have a lot of different industrially relevant issues in our work to create a demonstrator,” says Johannessen.

Hurtigruten is also very pleased to have its ground-breaking ship tested.
“It’s fantastic for us that we can test all the parts of the Sea Zero design at such a professional and advanced laboratory as SINTEF has. Contra-rotating propellers are new to us, and they are not common on ships either. That’s why it is so important for us to be able to thoroughly test the ship design in the cavitation tunnel. Then we’ll know that it will work in practice,” says Larsson-Fedde.
Some challenges too
Propulsion efficiency is increased by recovering part of the energy loss from the front propeller and by better inflow to the rear propeller. That is why it is possible to achieve more than a 10% increase compared to conventional propellers. However, contra-rotating propellers require a complex shaft-in-shaft system.
“The design process is also more complicated than for conventional propellers, both because of complex flow phenomena and the larger number of parameters that need to be adjusted, compared to one propeller. This applies to both the diameter ratio and the propeller’s revolution ratio between the two propellers, for example,” says Rabliås.
It will be exciting to follow the developments in the future for Hurtigruten as well.
“The goal of Sea Zero is to design the world’s most energy-efficient ship, and in that quest we have to leave no stone unturned. The propulsion itself uses a lot of energy, and so contra-rotating propellers are very exciting for us to look at,” says Larsson-Fedde.
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Tech
6 Great After-Christmas Deals to Spend Your Gift Cards On
After-Christmas deals are an excellent way to redeem any gift cards or cash you got for Christmas. You can purchase something you actually want, and you can do it for less money than usual. I’ve scoured the Internet for truly good after-Christmas deals on the gear that we’ve hand-tested on the WIRED Reviews team. Many of these sales will end this weekend, so keep that in mind while you’re shopping. Find all the highlights below.
For more inspiration, check out some of our recently updated buying guides, including the Best Office Chairs, the Best Cheap Phones, and the Best Space Heaters.
WIRED Featured Deals:
Anker Laptop Power Bank for $88 ($47 off)
We love this beefy power bank. Its 25,000-mAh capacity is more than enough for fully charging your iPhone between 4 and 6 times, and it can deliver up to 165 watts to two devices meaning that you can charge your laptop, gaming console, or anything else you fancy. The built-in USB-C cable doubles as a carrying loop. There’s also a nifty display that’ll give you at-a-glance information on remaining battery, temperature, charging speeds, and more. It has pass-through charging support and only takes about two hours to fully recharge. This deal price matches what we saw on Black Friday.
Google Pixel 10 for $599 ($200 off)
There was an on-page coupon (PIXEL10) that had the best price we’ve tracked for any of the phones in the Google Pixel 10 lineup. That coupon is not available as of Saturday morning, but it may be back—clip it if you see it. This is still a good deal on the smartest Android phones you can buy, with fantastic cameras, snappy processors, gorgeous displays, and more AI integration than the average person needs. Check out our dedicated buying guide to figure out which Google Pixel 10 is right for you. If you’re in the market for an upgrade, now is a good time to buy considering that we’ve never seen any phone in this flagship lineup sell for less.
Bruvi BV-01 Brewer Bundle for $228 ($120 off)—Clip the Coupon
I’ve tested a lot of pod coffee makers, and the Bruvi BV-01 is my favorite. This deal price is the best we see outside of special events like Black Friday and Cyber Monday. The brewer is cute and looks great on a counter, with a large reservoir, an intuitive touchscreen display, and a built-in wastebin that collects used pods for you. The best part are the proprietary B-Pods, which are designed to biodegrade in a landfill. The bundle gets you the machine plus an assortment of bestselling coffee and espresso pods to get you started.
Fitbit Charge 6 for $100 ($60 off)
The Fitbit Charge 6 has been at the top of our fitness tracker buying guide since we first tested it. It’s attractive, affordable, accessible, and on sale for a match of the best deal we’ve seen. It’ll play well with iOS and Android, and it has a solid suite of features that’ll cover almost anyone’s needs—including skin temperature, heart rate readings, ECGs, activity and workout tracking, and more. The battery lasts for at least a week on a single charge. This deal comes with a six-month subscription to Fitbit Premium, which normally costs $10 per month.
Hydro Flask Standard Mouth Water Bottle for $30 ($10 off)
This budget-friendly deal gets you a steal on the best reusable water bottle. Hydro Flask bottles are durable, portable, and easy to cover in all the stickers you’ve been hoarding. The handle is flexible, the bottle is leakproof, and every component is dishwasher safe (though you may want to opt for hand-washing if you do end up plastering it in stickers). A few different colors are on sale at this price.
Beats Powerbeats Pro 2 for $200 ($50 off)
If hitting the gym is one of your New Year’s resolutions for 2026, the Beats Powerbeats Pro 2 are worth considering. They’re the best workout headphones we’ve tested thanks to their comfortable and ergonomic fit, noise cancelation, spatial audio, a heart rate monitor, and the fact that they play well with both iOS and Android phones. The sound is solid, the battery life is good, and they’re water-resistant. This deal price comes within $20 of the best we’ve seen. Every color—orange, lavender, grey, and black—is on sale.
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Tech
Hyperkin’s Competitor Upgrades the Xbox Controller by Copying Sony’s Design
The most immediately striking difference is that Hyperkin’s product swaps the typical Xbox approach of asymmetric thumbsticks for the PlayStation’s horizontal layout. It also separates the D-pad (it’s one piece inside the pad, but splits its cardinal directions so each appears to be its own button), while the ABXY face buttons are spaced slightly further apart. Where the DualSense’s touchpad would sit, we have the Xbox home, menu, view, and share buttons, all blended in rather smartly. An LED ring around the home button just about echoes the lights running the periphery of the DualSense’s touchpad, although it’s really more of an inversion of the regular Xbox controller, where the home button itself lights up.
The Competitor’s thumbsticks come equipped with thumbcaps that mirror the PS5’s, an outer ring with a convex central point, but a pair of Xbox-standard concave caps are included. These easily pop on and off, and can be mixed and matched, if you were so (strangely) inclined.
There are two areas where this departs from both the standard Xbox and PlayStation controllers in terms of inputs. The first is the presence of two programmable rear buttons, M1 and M2. By default, these duplicate the input of the A and B buttons, but holding down the Mode button between them lets you remap them. There are also physical button locks to prevent their use entirely. The other is that while the Competitor boasts a 3.5-mm headphone jack like Microsoft’s official pad, it adds a built-in audio mute button, hidden in the black between the thumbsticks—a nice little upgrade.
Oddly Familiar
In use, the Competitor feels … well, a lot like a PS5 pad. The slightly wider grip fits in the hand comfortably, all inputs are accessible, and those symmetrical thumbsticks sit nicely in reach for all but the smallest hands. A microtextured underside provides a solid grip that, when coupled with its 232-gram weight, makes the Competitor feel particularly suited to longer play periods. It’s all very familiar if you’re already a multiformat gamer, to the extent that it sometimes slightly threw my muscle memory off, reaching a thumb out to do a PlayStation touchpad function and finding only the Xbox system buttons.
Photograph: Matt Kamen
Tech
In Cryptoland, Memecoin Fever Gives Way to a Stablecoin Boom
When US president Donald Trump launched his own meme cryptocurrency on January 17, days before his return to the White House, I was halfway up a Swiss alp, attending a crypto conference in the town of St. Moritz.
Memecoins, which typically have no purpose beyond financial speculation, were having a moment. The previous year, millions of new memecoins had flooded the market; a few, like Fartcoin, had rocketed to billion-dollar valuations. Pump.Fun, a platform for launching and trading memecoins, had become one of the fastest-growing crypto launchpad businesses ever. Now, the soon-to-be president was getting in on the act.
Over lunch on the second day of the conference, beneath the ornate stucco ceiling and golden chandeliers of the venue’s dining hall, I located a table designated for a conversation about memecoins. Whereas other tables were half full, the memecoin workshop was oversubscribed; latecomers pulled up chairs to create two full rows.
The discussion was led by Nagendra Bharatula, founder of investment firm G-20 Group. Bharatula had recently coauthored a paper arguing that memecoins, despite their juvenile spirit, had a place in professional investors’ portfolios. In the six months prior, a basket of 25 “bluechip memecoins”—an oxymoron if ever there was one—had outperformed bitcoin by 150 percent, he pointed out. Some of the attendees murmured their approval.
Since then, the shine has come off the memecoin market. The paper value of Trump’s coin, which climbed to a peak of $14 billion two days after its launch, has cratered to roughly $1 billion. Hundreds of thousands of small investors lost their shirts. Pump.Fun’s daily revenue, a proxy for the overall appetite for memecoin trading, is barely more than a tenth of what it was in January. The memecoin gold rush has spawned a raft of litigation.
Next up: the stablecoin. If memecoins are symbolic of reckless abandon and unflinching profiteering in cryptoland, stablecoins are a symbol of the industry’s search for purpose and respectability. Designed to hold a steady $1 valuation, stablecoins are pitched by proponents as a faster and cheaper way to make everyday payments and international money transfers.
In a year in which the US has declared itself open for crypto business, where previously crypto firms feared regulatory backlash under the Biden administration, stablecoins have supplanted memecoins as the coin à la mode—and punctured the mainstream.
Though stablecoins have been around since 2014, they have predominantly been used by crypto traders as a safe harbor during bouts of market volatility, not by regular people. The concept has also faced resistance from regulators skeptical of a new form of money; Diem, a stablecoin venture incubated at Meta, famously shuttered in 2022 in the face of broad-based opposition.
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