props

[pW2]

I seem to have lost my graph for prop sizing and they ain´t got libraries in Spain so can some kind person tell me what size prop I need for 40hp at 1500rpm (at prop) expected speed 9-10 knots. and has anybody any idea of the axial and radial loads such a prop develops? The Boat weighs 5 tonsish.
Also can one still get that auto variable pitch job that was available some years ago? Is it any good?
Ta
W

 

[cliff]

Cannot compute - insufficient data!
Need LWL, hull type, weight of boat max dia of prop you can swing. etc

Variable pitch prop here
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"Artificial intelligence is no match for natural stupidity"

 

[pW2]

It never used to be so difficult, just like life!
She´s a cat 40ft weighs 5000Kgish prop diametre can be whatever but I thought the diameter was controled by the Hp of the engine and the pitch by the revs and speed, no?

 

[davidbains]

Is it just the one central engine on the cat, or have you got 2 * 40HP!!

 

[Evadne]

Have you tried the Javaprop calculator?
here ?

 

[cliff]

I suggest you contact some of the prop suppliers rather than the forums - at least then you have some comeback if they supply the wrong sized prop.
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"Artificial intelligence is no match for natural stupidity"

 

[ShipsWoofy]

Propeller calculator from Castle Marine

Enter hull type as semi displacement! That is how he did it for me when I was sat in his office.