[ian0]

Not really a disincentive, if the person paying the fuel could pay less it for it while using fleet X it would surely be a competitive advantage to the fleets owner. Perhaps the keyword in the quote is "untested", with a unwritten "why bother unless I have to / other owners do it".

[toss1]

Exactly. The key hurdle is getting the first ship fleet owner to invest in the technology. Once that's working, he'll have a competitive advantage offering renters lower fuel costs. He'll have some combination of higher booking rates or ability to charge higher prices, effectively splitting the gains