Goodbye U-Turning Supertankers as World’s Ship Fuel Is Upgraded

One of the more lucrative opportunities in global commodities markets is about to get a little bit trickier.

What might best be described as detour trades—ships switching destinations to profit from higher cargo prices—will become more challenging to execute in 15 months’ time because of changes to the kinds of fuel vessels must burn, according to several industry analysts and a former engineer for A.P. Moller-Maersk A/S.

The deviations, often delivering outsize profits to traders, will become tougher for two reasons. The first is that fuel for the shipments currently looks like it will cost a lot more than ...