Ships are refitted for purpose all the time. Just how much JC1 needs refitting to operate F-35Bs is unknown. US LHAs had some refitting such as better non-skid in some deck areas along with secure comms & spaces suitable for secure F-35B briefings and such like. IF the Spanish purchase some F-35Bs (that is certainly their intention today) then in due course we may find out more about what needs to be done to an LHD. Meanwhile here are JC1 & Mistral side be side at Toulon recently.
http://www.defensa.com/espana/sh60f-...o-tropas-nh901
As Commander of the Aircraft Fleet I would love to see the LHD Juan Carlos I operating with the F-35B
Julio Maíz Sanz September 14, 2017
For the Commander of the Fleet of Aircraft of the Spanish Navy, the captain of the ship Jose Luis Nieto Fernandez, the only substitute of the AV8B + capable of operating in naval platforms like the LHD Juan Carlos I is the F-35B. In the second part of this interview we discuss the replacement of the Harrier and the future needs of FLOAN in order to adapt to the new scenarios
Q: With respect to the Harriers, is it planned to modernize or implement their equipment and / or armaments in order to increase their capabilities? How long will they be operational? Is the F-35 the only possible substitute?
A: The AV8B + aircraft of the Ninth Squadron embarked on the LHD Juan Carlos I are a fundamental element of the naval power projection capacity. As we all know, the program to support this aircraft is multinational between the countries that operate the Harrier (Spain, Italy and the United States) and both the United States Navy and the Italian Navy will gradually replace the AV8B + with the F35 Joint Strike Fighter, although to this day it is not defined yet when the definitive fall of the Harrier will occur, everything seems to indicate that it will not be before 2030.
What is clear is that the only substitute of the AV8B + capable of operating on naval platforms such as the Juan Carlos I LHD is the F-35B that has short take-off and vertical takeoff capability, so the Navy considers it an option to maintain a robust projection capability of naval power. As Commander of the Aircraft Flotilla and pilot of AV8B + I would love to see our LHD Juan Carlos I operating with F-35B of the Aircraft Flotilla...."