Prop question

[Hokuao]

Hi,
I have a Pacific Seacraft 31 with a Yanmar 3YM30. I currently have a two blade fixed 16 inch prop on a 1 inch shaft that is in need of replacement. The yard manager told me I needed to find out what my boat’s max speed is before deciding on the new prop? Is that necessary and any prop suggestions would be greatly appreciated.
Thanks

[CarlF]

Putting a folding/feathering prop on will substantially improve your sailing speed while improving speed/fuel efficiency under power.

All of these prop companies will recommend a size and pitch if you fill out the form on their web site.

Max-Prop is an excellent choice:
https://www.pyiinc.com/max-prop.html

Another option is the fixed prop Campbell sailor prop. They too will recommend size and pitch
https://westbynorth.com/campbell-sailer/

In most cases it's best to call the prop company. It's likely they've fitted a prop to a Pacific Seacraft with your engine.

Yes these cost more but I've never known anyone who went to a folding or feathering prop who went back to fixed. You will typically gain 1/2kt or more in speed.

[Kijit]

We replaced the fixed blade prop on our boat with a Flexofold prop several years ago and are very happy with the performance. Their recommended size worked out fine.

https://www.flexofold.com/

[FPNC]

Below is the minimum data that a prop shop needs to run an accurate propeller calculation.

Vessel LWL
Vessel displacement while fully laden
Engine continuous rated HP
Engine continuous rated RPM
Transmission gear reduction
Maximum diameter propeller that will fit the vessel

[JimsCAL]

Do you know what the pitch is of your current prop? And what RPM does the engine run at when you have the engine at full throttle? Ideally the engine will be running at close to its rated RPM when running at full throttle.

Basically to order a prop you need to specify diameter, pitch, RH or LH, and shaft diameter.