What causes Porpoising

[htillman]

Thanks, this little boat was fun putting together.
The hull sides were sprayed with Imron. I am going to paint the bottom with Signature Finish dark blue. I removed the prop and had to re-rig the engine; the cables (controls, fuel and oil) were kinked when the motor was originally installed. During this process I bulk head mounted the hydraulic steering cables, replaced the water pump and tuned the engine. She really runs much better now with the prop and engine work. Found out this engine only had 85 hours.
There is a big difference (ride, storage, etc) between the 20 and 23. I really miss the 23 and have been looking for another one. Just not sure what model?