I see that the engine has doel fins added to it. This suggests that it was thought to be slow to plane by whoever had them fitted. Could be that the engine is undersized for the hull, or that the weight of the engine made the hull stern heavy. What is the max hp for this hull? It should say on the hull plate - take a look when you go for the sea trial.
Personally I've always though that doel fins are a bit of a bodge to fix undesirable characteristics that should have been engineered out properly, either by design or by fitting trim tabs/better weight distribution etc. I feel that if doel fins are truly worthwhile they would come fitted from the factory. Just my 2 pence worth though.