The answer is in the F18 class rules. Oooops, it doesn't sound like a development class indeed.

"PART II – REQUIREMENTS AND LIMITATIONS
The intention of these Class rules is to ensure that the boats are as alike as possible in all aspects affecting performance as F18 is a Measurement Controlled Class. The crew and the boat shall comply with the rules in Part II when racing. In case of conflict Section C shall prevail.
The rules in Part II are closed class rules where anything not specifically permitted by the Class rules is prohibited. Certification control and equipment inspection shall be carried out in accordance with the ERS except where varied in this Part.