"Sweet Spot" for engine RPM

[Hogfighter]

I have a Hunter 430 with a Volvo Penta 50 hp and MaxProp 3-bladed. The max RPM that I can achieve is around 2,800. I'm wondering what speed/RPM everyone is getting with their 430s. At 2,000 RPM I'm getting 6.8 knots. What do you cruise at (RPM wise), and what speed does that give you? Additionally, if anyone has the charts on RPM/fuel consumption for this engine, I will think highly of you. Thanks!

 

[Alan]

Are you sure about the pitch setting on the prop? The correct pitch setting is critical to achieving maximum RPM's and HP rating. The wrong pitch can be destructive to the prop.

 

[Rich Stidger]

I have a V-P MD22L-B 50hp in my 1997 h40.5. It may be the same engine that you have in your 430.

The MD22L-B has a WOT rating of 3000 rpm and I can drive at 8.2kt at that WOT setting with a clean bottom, calm seas, and no headwind.

I normally cruise at 2400-2500 rpm and my boat speed is about 7.4kt.

Attached is page two of the MD22L spec sheet that shows a fuel consumption curve.

 

[Hogfighter]

Thanks, Rich! I have been hesitant to go much above 2,000 RPMs, but after hearing from you and looking at those charts, I'm much more inclined to cruise around 2,300. Much appreciated.

 

[Rich Stidger]

Remember that diesels love to work. The recommended cruising speed is at 80% load. This is not 80% of WOT. The Volvo East Coast Tech rep told me that I could run at 2600 rpm 24/7, and that was his recommendation.

He also recommended that I run at WOT for 10 minutes each time I went out. The reason was two-fold. First to confirm that the engine and drive system was actually capable of achieving WOT so that if needed it would perform. ( Engine OK, prop clean, etc...) Second was to clean out any deposits that were accumulating. I do this once per weekend cruise or once per week.