Scott3:
NZ boat makers have a habit often advertise their boats as having ligher towing weights than are realistic.
That probably used to be a worse problem than it is now - before they increased the limit for override brakes from 2 to 2.5 tonnes.
The other parts of that requirement is for having two same-length safety chains crossed over if 2 - 2.5 tonnes. If the trailer comes off the hitch, then the draw bar is supposed to not hit the ground and should stay centred. Fine in theory, but will depend on tow bar height and fixing points for the chain. I've never had that checked at WOF time.
Over 2.5 tonnes requires breakaway / electric brakes.
