Boat won’t plane out

[Merc45hp]

I have a 14 foot tri hull bass master I bought a 45 hp merc mariner from a pontoon it runs great but it won’t plane out I have even added a jack plate with a 8 inch drop after adding it with it dropped about 4 inches it will get about 1/4 planes out does anyone have any ideas

 

[mr 88]

Coming off a pontoon boat my guess is your prop is under pitched or for some odd reason over pitched , depends on what your getting for max rpms right now. Next up would be your way underpowered depending on what your max HP label says. What motor was on it when you bought her ? You could have a waterlogged hull or too much weight in the stern . Hard to say without more info.