Adjusting prop pitch .. Doesit make a difference?

[CelebrityScandel]

In response to me you asked...

What is the meaning of this "range of maximum rpm"? Does it mean that any rpm within that range are OK?
For instance the manual of my MD2030D says maximum rpm 3200-3600 rpm. I can achieve (easily) 3500 rpm. Does the range "allows" me to use a stronger pitch propeller and achieve only 3300rpm with no problem?

Regarding "with no problem" you need to ask the engine manufacturer's representative.

For ourselves we have generally gone for lowest RPM in the range but that has been done through discussion between the engine supplier and the prop supplier and we have just taken the prop that was recommended out of that. It has always worked.

Frankly, I have no idea whatsoever why people try to get prop recommendations on forums or play around with the various calculators. A good prop builder will recommend a prop for free and stand by his recommendation, even for small sail boat props, through at least one rebuild should that prove necessary.

Our only reasons for going for the lower end of the rev range has not been for any other than ease of getting high generation rates from service alternators at low engine RPM's (when charging at anchor) without exceeding max alternator RPMs when at max engine RPM and for less engine noise at cruising speeds.

 

[charles_reed]

Phew!, I'm glad I've got a Brunton's Autoprop to do all that for me.

In fact there's some very careful analysis and complex equations in the Brunton calcs.

I had one of the earliest and was involved in some of the work.

Interestingly my change from 18bhp to 23bhp and an increase of 38% in torque was accommodated by the same prop - just.