From an International perspective sailnumbers can be managed by a National Association in any way it wishes. All we require internationally is that each boat should carry its country designator, USA, GBR, AUS etc.

Many classes are now following the numbering principle that, I believe, started with windsurfing, where the number 'belongs' to the helmsman/owner irrespective of the boat and therefore the boat requires a separate hull identifier. With serial numbers/registration numbers required by various Authorities this should not be a problem. The important thing will be to ensure that these ID numbers appear on the F16 measurement certificate.