Propeller selection

[Andre girouard]

Hi.I need propeller recommendations for 3 different boats.First i need a prop for a k&b 3.5cc outboard (stock, un modified) on a 30" wood tunnel hull. Second a prop for a 30" deep vee using a 3.5cc inboard( .21dynamite car engine with a tuned pipe).Im interested in sport boating only, 30% nitro will be the maximum .And third im building a scale boat (a patrol boat, similar to a vietnam river patrol boat, 1/10 scale).Fiberglass hull, wood superstructure.It will be powered by a 4 cycle trimmer engine converted to rc marine use (watercooled ).My performance requirements are simple, that it operates in a scale like manner , that it is able to get up on plane at full throttle.
I already checked the balance point and it is proper with the motor and fuel tank(with fuel) in place.I Will be using octura props, they are the easiest for me to get.I already have an octura 1475 on my gas powered deep vee, would this be suitable.Dimensions for the patrol boat are 50" x 19".Thank you

 

[Wasted wages]

Other than the tunnel hull, how are the other boats set up on the drive systems?

Sub surface ?
Surface drive ?

It's going to make a difference on prop selection..

 

[Andre girouard]

Both the deep vee and the patrol boat will have sub surface drive.Im using octura strudder set up.Thanks

 

[Kez]

For the 3.5 inboard and outboard, I would start with an X440. If by subsurface drive you mean the prop is completely below the water when the boat is up on plane, I would go smaller, like X438

 

[shoboat]

Andre,

I would try an Octura X-437/3 on both the 21-Tunnel and 21-Mono.
On the patrol boat a X-467 or X-470.

Happy Holidays,

Mark Sholund