You might want to check an actual boat. If you put Infusion hulls on backwards they cant inward instead of outward. I wouldn't call that symmetrical. I think the boat uses four hull molds too.

I would check with ISAF that they think that implicitly referenced rules are enforceable.

I'm fine with making rule say that the hulls shall be symmetrical. But, the rule shouldn't be implied. It should be explicit and clearly articulated. The AC72 rule (written by Pete Melvin) does a good job wording this by defining areas of the hull shells that shall be symmetrical and areas that can be symmetrical.

Rules that are implied or require knowledge of the rule's intentions are bad rules. Good rule clearly define what is and what is not legal. A good rule has well defined terms and must have a way to test if the rule is followed.

A lot of this is made difficult because F18 uses closed class rules instead of open class rules. In a closed class the ERS say, "anything not specifically permitted by the class rules is prohibited." So, the rules have to say "specifically" if symmetric hulls and/or asymmetric hulls are permitted. So, the rules need to be thorough enough to describe everything on the boat. The rules are not at that point.