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Comment by kkoste | Hacker News Reader

But does the overall cost of these 'WindWings' recoup over the lifetime of cargo ship. Including the fact that they can now carry less cargo per trip. And the trip might take longer due to 'route optimizations'. Insurance is probably also going to be higher now that you have giant sails on top of the ships that makes it both more expensive but also i suspect less safe in rough seas(even when folded).

I feel that is the only true measure otherwise cargo ship builders are not inclined to build more of these.

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> But does the overall cost of these 'WindWings' recoup over the lifetime of cargo ship.

Well... 1 ton of bunker fuel costs about 650 dollars, so you're looking at 7.5k saved each day, or 150k per trip (assuming an average of 20 days at sea). Cargo ships have ridiculous life expectancies measured in decades, so it's very likely to make a significant dent.

[1] https://www.statista.com/statistics/1109263/monthly-vlsfo-bu...

Cargo ships cost $100 million or thereabout, and operate for at least 30 years. Estimating that about 1/3'rd of that is time where these would be useful, this would save about $27 million and the savings grow with inflation, so that's no small change.

> savings grow with inflation

Wat?

If you're saving a $1 in fuel today, then in ten years doing the same thing you'll save more than $1 because fuel will cost more.

I'm not sure it's a useful characterization, since inflation affects everything, but it's not wrong.

Cargo ships have ridiculous life expectancies measured in decades, so it's very likely to make a significant dent.

Note that 12 tons/day was the best case, the average was 3 tons, so that's more like $2000/day or around $400K/year assuming the ship is at sea 200 days/year.

Anything on a ship with moving parts has significant maintenance costs, so it'd be nice if they had a ballpark figure of the installation/maintenance costs as well as expected lifetime of the system.

And what happens in a serious storm? It looks like these can be rotated but not folded down flat, so what happens in unpredictable winds during a storm?

They do fold flat [1]. [1] https://youtu.be/AB7cLkSVmJA

Oh that's cool, in the photo in the article they looked too tall to lay flat without interfering with each other.

3.3 tons of fuel per day adds up to a lot of extra cargo that isn't fuel.

A lot of these ships carry upwards of 150000 tons of cargo. Not sure if an extra 60-70 tons (assuming a 20 day trip) of cargo would be very meaningful. A quick google suggests that would only be 2 or 3 additional shipping containers.

You don't need to compare to the size of the ship, you need to compare to the size / mass / cost of the sails.

There’s also the cost of the fuel. Can’t be cheap.

I guess the question is how much space would the sails take.

The fuel is around the bottom hull of the ship. It provides good stability to the ship. As you use fuel you'll often take on sea water as ballast to regain the lost stability and to maintain your draft.

These are not simple machines.

That is because of the difference in mass over the voyage, the less delta in your fuel math the less of a problem it is. Also, nothing prevents you from doing exactly this with a smaller amount of fuel. Last I checked dense liquids continue to be dense liquids and will flow to the lowest point.

Do they use separate tanks or does the water go into empty fuel tanks?

Seawater is initially filtered and goes into ballast tanks that have very special yearly inspection and cleaning procedures. If you just go into a chamber that has been empty/full of seawater for a couple months you can drop dead because of CO2 buildup (or some rusting processes that eat up oxygen). Credit to sailor(s) who post about things like that on hejto.pl.

It's even more fun with clean water tanks (painting and cleaning, specific concentration of chlorine for a day plus taking samples and eventually more chlorine before flushing).

Might be slightly inaccurate as I'm writing from memory.

> If you just go into a chamber that has been empty/full of seawater for a couple months you can drop dead because of CO2 buildup (or some rusting processes that eat up oxygen)

And deadly hydrogen sulfide. "Hydrogen Sulphide can be found in tank sediment as a result of decomposing sea life which may enter the tank[.]"

https://www.imca-int.com/safety-events/crew-member-fainted-a...

Can confirm that sea water corrodes everything. I used to live on an island and we joked that it even corroded plastic. In practise it was the UV that killed all plastic, while the sea water ate all the metals, including stainless steel.

Bold words from a nanomachine hivemind that thinks 21% corrosive oxygen is normal. :p

The first climate catastrophe :-D or as Bob Ross would put it, a happy little accident.

That's approximately two Honda Civics.

The calculation is perverted by the free externalities of dumping carbon in the atmosphere, a very expensive discount. I know it's not news, but it perverts economic decisions.

The problem is that while that has no dollar value attached, the companies dont care.

It would be good if there was some global carbon tax that required equivilent carbon biomass be grown from scratch to offset emmisions. Said biomass could the be processed and stored.

Its not really a tax, its taking responsibility for the waste you produce.

Same goes for plastics. If a plastic is used in manufacturing in a way that means its going to get thrown oit eventually then that company should be responsible for collecting that amount of that said plastic from garbage and storing it long term.

This would hopefully drive people to the most efficient solutions. Some fossil fues and plastics would still be used but their negitive effects would be offset by the collection and storage process.

Right, that's what I mean by externalities.

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