The boat and engine were packaged together from new so pretty sure it's the correct prop.
Thinking back the inflatable keel might have been a little off centre, didn't think that would have a detrimental effect but after reading these posts maybe that could have been to blame.
As for weight distribution, we had 2 blokes near the back and 2 women on the front bench so I think it should have been fairly even.
The rubber hub slipping could be a posibility, definately worth wipping off the prop to have a look me thinks.
The doel fins could be worth considering if I don't manage to sort it, I'd rather not drill the anti-ventilation plate on a nearly new engine though, bit of a last resort really.
Thanks for all the input guys