prop pitch

I just bought my first inboard I have always had outboards. The boat that i bought was a cruiser cut down and made a workboat it has a 318 chry gas 4 barrell engine it is 34ft 10 ft beam it is a wood boat, dont know the rpms the guy did not have a tach in it I am giong to put one in it. I have the boat in dry dock now the prop is 15 -12. I could only get 11-12 knots out of it. Would a higher pitch get me any more speed or would it kill the engine.I can not put a taller prop because of room. It has a 1-1 trans.If the prop wont help other than putting a bigger engine in it, is there anything else I could do to pick up a few extra knotts

 

Pitch Calculation

Dear ems
Please kindly fill the '' propeller sizing form '' on www.erispropellers.com .I will calculate the pitch and reply you immediately .

 

You are limited because of propeller space. You need more propeller surface area, which in your case, can only be obtained with additional Blades. Also the 1 :1 trans necessitates a very low pitch which is less efficient.

Either a 4 or Preferably a 5 blade, 15 x 9 or less pitch should get you a few more knots with your present setup. I suspect your current pitch (12) is already choking the motor and lack of blade area is causing huge slippage.