Another prop question johnson90 1986

[cat5cable]

Hi all i have read a lot about props but i am still confused, so i have a johnson vro v4 90hp year 86 on a osprey 5.6 metre rib it also has trim tabs fitted, i have 2 props 14x13b and 13 1/4 x 17 the first one is plastic second is aluminium, so what does the b mean?? also what prop would give me the best top speed at the moment rib has the 13 1/4 x 17 and this gives us about 28knots at 5300rpm but she will rev to 6500 but boat stays at same speed and you can hear the engine rev out.

Thanks
tim

 

[kynolan2183]

Re: Another prop question johnson90 1986

The b means that it is cupped more than likely.
The 17 pitch prop might not be cupped and you are venting to the surface when your RPMs go up.

In other words the increase in speed to the prop has caused a tiny hole in the water, like the whirlpool formed in the crapper and the prop has less to grab and push the boat. RPMs go up but speed drops or stays the same.

If you can't trim it you might need to lower the motor or get a steel prop that has 2Xcupping and that is designed to come out of the water a little.
I think the bass guys call it a cleaver?

Try trimming down a little when you get up to the 6500 rpm.
This is not uncommon, my bass boat does it if I trim her up to high.

A boat is like a woman, no matter how much money you throw at her she will still find something else to complain about.

Kyle

 

[cat5cable]

Re: Another prop question johnson90 1986

Thanks i will try that sunday, is the 14x13b prop slower or better for holeshots
tim

 

[JB]

Re: Another prop question johnson90 1986

Prop questions belong in the Prop Forum. Going there.

 

[kynolan2183]

Re: Another prop question johnson90 1986

Correct the plastic prop will be for hole shots.
But a steel prop at the higher pitch of your aluminum will give you the hole shot of the smaller pitch.

Kyle