Ok I did research
Marine diesel is 475 usd a ton spot on USGULF
most 70 meter plus motor yachts have 500,000 to 1,000,000 capacity fuel in liters
Gallon = 3.78 liters
Hence
If full tank made of empty
1000000/3,78=264,550
316 gallons marine diesel number 2 per ton
264550/316=837 tonnes of diesel number 2 at 474/ton
Equals 396,000 bucks
It is possible
That’s equatorial circumnavigation and then some range
Latest exchange rate has GBP 1.00 = 1.37 USD
So that 250,000 GBP to fill their bunkers is really only 342,500 USD. Not far off your figure.
Costs them a pile to fill up, but they don’t have to do it very often.
There’s a dude who sometimes stops to talk to one of my morning coffee pals. Drives a Lambo and an AMG. Kinda looks like what you think a pirate oughta. I don’t know him but he seems decent enough. He has an 86 ft... Sunseeker? Something like that. A few days ago he says “Oh, I bought another one. Somebody was eager to get out from under it and the deal was too good to pass up”.
Another of my coffee crew is looking to buy a blow up kayak. We are a tolerant bunch who don’t discriminate against the rich.
“Equals 396,000 bucks”
About 2-4 hours income to the super rich.