Some prop advise needed

[denlou]

I have a 16' Wellcraft Airslot w/hull weight of 1060 lbs. powered by a 1986 Johnson 150, j150tlcdc.
Total weight with 2 aboard should be abt. 1800 lbs.
Existing prop is omc 389924, 14 1/2 x 19.
The motor is mounted 2 holes up putting the cav plate 1" up from the hull bottom.

The motor will turn 5800 at near full trim, if I trim up any further the boat starts getting squirrely (sp?).
The boat performs very well and the top speed (my wag mid 50s) I'm happy with.

I know I need to step up in pitch to something like 14 1/2 x 21 but here's my dilemma.
With the motor turning up to 5800 the rev limit on the power packs is also 5800 so how do I know if that increase in pitch will be enough to keep me at or abt. the 5500 rpm redline ?

The new prop will be aluminum ($) whereas the existing is stainless and I'm thinking abt. the Solas Amita, any better recomendations ?

Thanks in advance
Dennis

 

[Robbabob]

Re: Some prop advise needed

denlou,

Hard to know you're not actually hitting that rev limiter with more throttle to go. Going with the higher pitch is the right direction, but also realize the AL is usually less efficient and may increase rpm without any benefit.

Just asking... Is that the rated HP for the boat? Seems you may need to go to a 23P. Is testing an option?

Good luck!

 

[denlou]

Re: Some prop advise needed

I'm just a wee bit over on the rating.
I was thinking about testing but figured I'd be locked in to what props they carry and of course higher $.

 

[Robbabob]

Re: Some prop advise needed

Might assume you have a little more throttle left than the 5800 you're rev limiter is hitting. I would tend to be more comfortable with a 3-4" pitch increase. Trouble is, your speed will increase; higher than safe.... but you're already over the HP rating so you're at risk as it is.