Sabre 34 prop size?

[HOBO-S34]

I have a Sabre 34 with a Westerbeke 30B engine. My cruising speed at 2700 RPM is max 5 knots. I can get a little more speed if I up the rev's to 3000 plus (only did that as a test). I think I am under proped. Any suggestion for a three bladed prop size. Boat is relatively new to me and I do not know the prop size.
Mike

[Laidback]

Originally Posted by HOBO-S34

I have a Sabre 34 with a Westerbeke 30B engine. My cruising speed at 2700 RPM is max 5 knots. I can get a little more speed if I up the rev's to 3000 plus (only did that as a test). I think I am under proped. Any suggestion for a three bladed prop size. Boat is relatively new to me and I do not know the prop size.
Mike

Hello Mike,
The Hull Speed on the boat is 7.12 knots with clean hull and excellent conditions under sail
The engine produces max torque at 2,021 RPM - and 19 HP.
For best consumption/speed/sound - around 1,800 RPM.
Max rated RPM on that engine is 3500 = 27 Hp
Your cruising speed is 5 knots at 2,700 RPM (+/- 22HP)

Before, buying a new prop with different diameter or pitch.
Dive and check the prop and hull for fouling. It they are clean, measure the diameter - can't measure pitch easily under water.
The Sabre 34 may have a user group who can advise on the size/pitch they have found best suits the engine and the gearbox's reduction ratio.