Exactly. If the charterer has to pay less fuel for your ship because you put a kite on it, surely they will choose your ship over others? Is there no competition in this market or why does fundamental market principles seemingly not apply?

It's one extra level of indirection. In the housing market, landlords do sometimes pay for upgrades to their rental properties, but they are less likely to do so than owner-occupiers.

Additionally if the ship owner was also the operator, they could benefit from some vertical integration, training their crew on the new technology.

If the effect of the kites on prices becomes large enough or the technology becomes standard, expect widespread adoption, but it's a reasonable claim that the existing market structure slows rollout when it's only marginally profitable.

> In the housing market, landlords do sometimes pay for upgrades to their rental properties, but they are less likely to do so than owner-occupiers.

Is that a fair companrison? An owner occupier will often over capitalise because they desire something or have a lifestyle benifit beyond money. A rental owner wil look at dollars in/out. With the ships, its all coming down to a spreadsheet of cost vs benifit for both owner and hirer.

I guess the point is that these systems have to be retrofitted to existing ships. The ship owners don't see the benefit - it costs them to do the modification - and the ship renters don't see the benefit, because ultimately the owner passes on the modification costs to the renter, displacing the fuel cost savings.

Whats needed is for regulation to come in and say 'ships that have these systems pay less to dock in port' or whatever. But, the technology has to be proven to reduce costs and carbon footprint - so someone needs to make an investment to prove this works before governments will get behind it.

I think this was replaced with Rotor Sails (which have indeed been installed on Maersk ships): https://en.wikipedia.org/wiki/Rotor_ship

I guess a complication is that you need to know how to operate the kite. And there is the risk that kites get broken or go missing.

there is an initial cost of the sky sail that is amortized over many journeys