Fletcher 238 Prop Sizing

[CPD]

My friend has bought one of these fitted with a single Landrover 300TDI diesel (110BHP) and alpha 1 sterngear.

The engine will run at 2000rpm max at which point the exhaust is seen to be running red hot and boat speed approx 15kts.

The propeller is 14" x 19 pitch 4 blade.

Am I right in thinking that a reduced pitch prop might bring about more revs but less exhaust temp for approx the same boat speed ?.

Many thanks for all comments .

 

[BruceK]

It's basically correct but for performance a lot more complicated than that. That prop is suitable for 135 up to 300hp outboard so it's probably a bit too coarse for a 110 diesel especially if the alpha 1 is a 1:1.47 gear ratio. Knowing that gear ratio is probably the most important start in prop selection.

 

[BruceK]

Have a look at this chart.

https://www.generalpropeller.com/pdf/QS_Mercruiser.pdf

23 foot boat, anticipated speed 22-30 knts prop suggestion is around 14x15 3 bladed props.