Another Propeller Thread - Volvo Duo Props

[leonfoxyy]

Hi all, I have a pair of KAD44’s in a 32 foot sports cruiser and have different gear ratios to factory spec (1.95:1 vs the factory 1.68:1) therefore my props are turning slower for a given engine RPM.
I’m running (incorrectly I know) Michigan A7 props which are giving me about 26 knots cruise at 3000 RPM and 34 knots at WOT (3800 rpm).
It feels slightly under propped and I have some mild vibration around 2000 rpm following a tangled fishing net incident therefore I think I have a bent prop and its a good time to consider moving to the recommend stainless C series if I’m going to replace damaged props potentially.
My question is: would a C7 prop set give me a little more pitch compared to the A7 Alloy versions?

 

[Momac]

https://techzon.bg/wp-content/uploads/2020/03/Volvo_Penta_propeller_guide.pdf

Make your own judgement based on the prop guide .
But it does look like C7 would give you more pitch. Whether this would translate into satisfactory performance I would not like to say.

Has the boat been re-engined ? if so what engines did it have when new and what would its top speed have been ? Is it wise to seek greater speed than the hull might have been designed to safely sustain?

 

[leonfoxyy]

Many thanks for the reply. No not re-engined, just re-outdrived. The boat has a hull speed of circa 38-40 knots max and cruise around 30 knots.