5 ms·

So, they are saving 14% and expect to multiply that by 1.5 by having an additional wing. Is there any prospect of getting near 100%? Naively 15 wings would get

by ajb 3y ago

So, they are saving 14% and expect to multiply that by 1.5 by having an additional wing. Is there any prospect of getting near 100%? Naively 15 wings would get there. From the image maybe 7 would fit on this ship without a redesign. Once it's proven, will it gradually evolve to taking more and more of the energy requirements? Obviously I realize there has to be some fuel in case the vessel would be becalmed, but apart from that, what are the limits?

ilkke 3y ago
Why stop there? Add more than 15 sails and you could be generating fuel!
- wolrah 3y ago
  > Why stop there? Add more than 15 sails and you could be generating fuel! AFAIK there are a few companies that have been adding electric drive systems to sailboats that actually do work this way, not only can it be used to maneuver around when the wind is uncooperative but it can generate power when the wind is good, basically acting as a "hybrid" of sorts where hypothetically given enough battery storage and maybe some solar it could be possible to never have to plug in or run a combustion generator.
- wolverine876 3y ago
  Why not put a windmill on the ship and generate electricity, turn the screw, and drive the ship? Not as efficient?
  - willcipriano 3y ago
    If it works what prevented ancient people from building windmill ships?
    - dotps1 3y ago
      likely lots of moving parts with a less-than-ideal place to be conducting regular repairs
      - willcipriano 3y ago
        My guess is it's a "equal and opposite reaction" sort of thing.
jtbayly 3y ago
You can fit that many, maybe, but most of them won’t be able to effectively harness the wind as the other sails will interfere.
- ajb 3y ago
  Yeah, was wondering about that. Once you have to start extending the deck or mounting them on tugs the trade doesn't seem likely to be favourable.
akira2501 3y ago
They're saving 12%, on the best days. The average is 3.8%. What's not covered in the article is the weight of the devices and the amount of cargo that must be removed from the load to support them. Without that you can't project forward at all. And even so, you're never going to get to 100%. Cargo ships need electricity to keep cargo refrigerated. They need to be anchored for long periods of time. They need to navigate harbors and other channels.
- ordu 3y ago
  > They're saving 12%, on the best days. The average is 3.8%. According to the article it is 12 tons/day on the best days and 3.3 ton/day average. 14% average with 37% max for reduction of greenhouse gases emissions.
- ajb 3y ago
  Where are you getting these figures? They aren't the same as the ones in the article.
nradov 3y ago
100% of what? In principle with favorable winds a large merchant ship could cross an entire ocean using sail power, but it would be very slow. Due to capital expenses, crew wages, and customer demands that wouldn't be economically viable. Even with "slow steaming" to save on fuel, merchant ships on long crossings are generally cruising at least 13 knots. There's no way to consistently hit such a high speed on a large vessel with any practical sail rig.
dghlsakjg 3y ago
> Is there any prospect of getting near 100%? A sailboat. The word you are looking for is a sailboat. Sailing cargo vessels have a number of issues with economics, which is why we stopped using them 75 years ago. There are some people using them in limited capacities, but for the most part we can't replace our global shipping with them. Speed is one. Even the fastest sailing cargo ships, which carried very limited cargo averaged 15ish knots on favourable routes. Modern motor cargo can travel at 20+ knots on almost any route. Even the largest metal hulled sailing ships that lasted until the 1950s carried an order of magnitude less cargo than a small container ship today. And take more crew to handle. The other issue is that sailing to windward is still not solved by this, and just from looking at the design, I would guess that it actually decreases fuel efficiency on any route that requires you to go into wind. The other problem with stacking more of these onto a ship is that you have to counterbalance both the weight and the lateral forces. Sailboats do this with a keel. Adding a keel to a large bulker like these is expensive, and will limit the ports you can visit due to draught, which will already be limited by the enormous sail keeping you from transiting under bridges.
- brianwawok 3y ago
  Cargoships would gladly go slower if they burn less oil. In fact they generally opertate nowhere near their top speed for this very reason.
  - dghlsakjg 3y ago
    Yes, but slow-steaming for efficiency on a cargo ship is ~18 knots, which is still above the upper speed of the fastest sustained speed of sail cargo vessels. You can slow further for efficiency, but you hit a tipping point pretty soon where you end up costing yourself more in time than you save in fuel. Realistically, a sail cargo ship is going to move along at a rate less than 10 knots. And of course this is all on a route with favorable winds. If the winds are against you, all bets are off. The same is true of these wingsails, there are limited routes where they will be efficient. Anything going up-wind is actually going to be a loss.
- gravescale 3y ago

by ajb 3y ago

ilkke 3y ago

Why stop there? Add more than 15 sails and you could be generating fuel!

wolrah 3y ago
> Why stop there? Add more than 15 sails and you could be generating fuel! AFAIK there are a few companies that have been adding electric drive systems to sailboats that actually do work this way, not only can it be used to maneuver around when the wind is uncooperative but it can generate power when the wind is good, basically acting as a "hybrid" of sorts where hypothetically given enough battery storage and maybe some solar it could be possible to never have to plug in or run a combustion generator.
wolverine876 3y ago
Why not put a windmill on the ship and generate electricity, turn the screw, and drive the ship? Not as efficient?
- willcipriano 3y ago
  If it works what prevented ancient people from building windmill ships?
  - dotps1 3y ago
    likely lots of moving parts with a less-than-ideal place to be conducting regular repairs
    - willcipriano 3y ago
      My guess is it's a "equal and opposite reaction" sort of thing.

jtbayly 3y ago

You can fit that many, maybe, but most of them won’t be able to effectively harness the wind as the other sails will interfere.

ajb 3y ago
Yeah, was wondering about that. Once you have to start extending the deck or mounting them on tugs the trade doesn't seem likely to be favourable.

akira2501 3y ago

They're saving 12%, on the best days. The average is 3.8%. What's not covered in the article is the weight of the devices and the amount of cargo that must be removed from the load to support them. Without that you can't project forward at all. And even so, you're never going to get to 100%. Cargo ships need electricity to keep cargo refrigerated. They need to be anchored for long periods of time. They need to navigate harbors and other channels.

ordu 3y ago
> They're saving 12%, on the best days. The average is 3.8%. According to the article it is 12 tons/day on the best days and 3.3 ton/day average. 14% average with 37% max for reduction of greenhouse gases emissions.
ajb 3y ago
Where are you getting these figures? They aren't the same as the ones in the article.

nradov 3y ago

100% of what? In principle with favorable winds a large merchant ship could cross an entire ocean using sail power, but it would be very slow. Due to capital expenses, crew wages, and customer demands that wouldn't be economically viable. Even with "slow steaming" to save on fuel, merchant ships on long crossings are generally cruising at least 13 knots. There's no way to consistently hit such a high speed on a large vessel with any practical sail rig.

dghlsakjg 3y ago

> Is there any prospect of getting near 100%? A sailboat. The word you are looking for is a sailboat. Sailing cargo vessels have a number of issues with economics, which is why we stopped using them 75 years ago. There are some people using them in limited capacities, but for the most part we can't replace our global shipping with them. Speed is one. Even the fastest sailing cargo ships, which carried very limited cargo averaged 15ish knots on favourable routes. Modern motor cargo can travel at 20+ knots on almost any route. Even the largest metal hulled sailing ships that lasted until the 1950s carried an order of magnitude less cargo than a small container ship today. And take more crew to handle. The other issue is that sailing to windward is still not solved by this, and just from looking at the design, I would guess that it actually decreases fuel efficiency on any route that requires you to go into wind. The other problem with stacking more of these onto a ship is that you have to counterbalance both the weight and the lateral forces. Sailboats do this with a keel. Adding a keel to a large bulker like these is expensive, and will limit the ports you can visit due to draught, which will already be limited by the enormous sail keeping you from transiting under bridges.

brianwawok 3y ago
Cargoships would gladly go slower if they burn less oil. In fact they generally opertate nowhere near their top speed for this very reason.
- dghlsakjg 3y ago
  Yes, but slow-steaming for efficiency on a cargo ship is ~18 knots, which is still above the upper speed of the fastest sustained speed of sail cargo vessels. You can slow further for efficiency, but you hit a tipping point pretty soon where you end up costing yourself more in time than you save in fuel. Realistically, a sail cargo ship is going to move along at a rate less than 10 knots. And of course this is all on a route with favorable winds. If the winds are against you, all bets are off. The same is true of these wingsails, there are limited routes where they will be efficient. Anything going up-wind is actually going to be a loss.
gravescale 3y ago