92 Chris craft Concept 258 prop sizing

[porscheguy]

Maryland. Just south of Annapolis.

 

[Mnormand55]

porscheguy hey man was able to swap that 4 blade out for a 21p mirage plus, picked up 4mph accorss the board at cruise and wot, i plan on picking up a 19p mirage plus to try aswell would get me more top end maybe, @ wot right now with the 21P i am 4700rpm, and would be curious to see the 19p and what it would do.. i belive you were on to somthing

 

[porscheguy]

Glad to hear you had such good luck with it. They really are good props.

 

[QBhoy]

Hi

just Reading all of this and all the way through was thinking you need a big diameter heavy swinging 3 blade like a mirage + 21” or even better a tempest plus 21”. Only just started to get to know the tempest. What a prop it is for heavy boats like this. So much lift it’s not real. Big enough diameter to keep the cruising rpm down (as in it behaves like a 2” pitch higher laser) but also able to keep a heavy hull up in there air the higher rpms too. Great prop. But a heavy bugger.
I might have thought your boat might see around early 50’s gps all being well and propped good enough ?
if she is a 1.5 ratio...then forget the 21” mirage and tempest. They be too big I’d think ?? Lesser ratio...yeah. 21” mirage or tempest all day !!

 

[QBhoy]

porscheguy hey man was able to swap that 4 blade out for a 21p mirage plus, picked up 4mph accorss the board at cruise and wot, i plan on picking up a 19p mirage plus to try aswell would get me more top end maybe, @ wot right now with the 21P i am 4700rpm, and would be curious to see the 19p and what it would do.. i belive you were on to somthing

Just saw this bit. I’d say that you are almost perfect at that ? Would that not put you right about almost perfect at those rpm ? The 19” would maybe see you gain about 300 rpm or so. Are you rated to about 4800 with that older version of the 454 mayne ?

 

[Mnormand55]

It's actually. 94 gen V 454 4600 to 5000

 

[Mnormand55]

But Yeh would like to try or have a 19p for loaded runs and to see top end of it would change mph wise with that 300 rpm