Someone recommended an A-cat via PM. I like that idea but could only afford one if I built it myself. Even then it would be stretch (in many ways probably).
I had a good laught out of this one !
That 9.15 mtr mast is not cartoppable by a loooooong stretch. Sure the boat is light enough to be placed on top of a car but the police will have a ball with that mast sticking out 3 meters on either side. Not too mention you'll be hooking every lamppost in corners of the road or picking off cyclist and truck drivers. You will be sweaping the road with that mast on top of your car !
Additionally the platform (nearly always glued together and therefor can't be disassembled) is still 5.49 mtr long and 2.3 mtr wide. That is quite a large object on top of your car !
I think the other criteriums you stated were "... take the kids out when its calm. It also needs to be low budget ..."
Humm !
Being in the Netherlands myself I can tell you the Police has gotten really strict with enforcing the rules in the last couple of years. Even with a trailer for your boat there is a high risk of getting a ticket these days. Quite a few buddies of mine have gotten one when trailering to and from an event. I wouldn't risk carrying something like an A-cat on my roof with the way things stand now.
Wouter