I'm looking for a new prop for my repowered Islander, but also a bit of an education on prop setup as I'm new to the offshore scene.

The boat currently has the Bravo Mirage 23p that worked with the stock 454 Magnum that was not running when I purchased the boat. A 502/500hp motor is going in its place. From what I've seen on comparable boats is a Bravo 1 24p is a common choice for this setup. What are the advantages/disadvantages of a 3 blade prop to a 4 blade unit?

1996 Baja Islander w/Bravo 1 drive, weighs 4400lbs, and occasionally used as a tow boat for wake boards/tubes but a fair amount of open bay ocean as well.

Thanks in advance!

That weight is real dry I believe...

Yep, I got that from the factory spec sheet. They probably even wiped the dew off the boat before hitting the scales.

Took it out this weekend with the new 502/502hp 23p Mirage Plus prop, and got 48mph on iPhone GPS at an indicated 4800rpm. Does that sound about right?

I need to check the carb linkage to make show the secondaries are opening completely as that seems a bit meek to me.

But one issue seemed to be the prop tends to suck a lot of air. Normal? Can that be tuned out?

Sounds like excessive slip to me.... I cruise at 50MPH @ 3,500rpm in my 26ZX Donzi with a 26P Bravo 1 prop...... My 502 is not stock but I would try a 24P Bravo 1 with your setup...... Make sure you are trimmed properly but it sure sounds like that prop is not working at all for you......

Yea, I thought of stepping up to a 24p as this is the stock prop on the 454mag that came out of the boat. I was surprised to see only 4800rpm on the tach, but as I was writing the previous post I remembered that this is a new setup and I better check that I'm getting full throttle.

Would a lower pitch prop tend to slip more? It blows out on any turn sharper than 50 yards regardless of the trim position.

you are getting very high slip around 31% you should be around 15%. I am surprised that your rpms were not higher, or even hitting the limiter it you had one. I dont know your speed before but you should conservatively add 6mph with the 500hp. i would try a 4 blade 26P bravo 1, it will hook up alot better.

Wow - 31%!

I did check the throttle throw and the secondaries are opening, and it has a Holley red fuel pump at 67gph at 5psi or 97gph free flow so that should be enough.

I was expecting to jump up to at least a 24 or 25p. It's weird that it won't swing a 23p beyond an indicated 4800.

rev limiter set low? tach not showing true reading? how did it run with the 454? speed, rpm? any other changes to boat?

I never ran the boat with the 454 as it came from the previous owner with a limping 496 truck motor. No rev limiter that I know of on the HEI ignition. The gauges do act kinda funny as if the dash panel isn't grounded well as the some of the switches "pop" through the stereo system, and if I turn the blower switch on it turns off the stereo all together so I know that I have to straighten out some of the previous monkey's work. What is the best way to verify the tach is working correctly? I don't mean to turn this tread into a troubleshoot thread as I do have one already going here.

What does 31% slip indicate? Not enough pitch?