Prop Help please BBlades
 

I have a 22' 454/330 bravo 1 drive and I am spinning too much RPM. It is a deep drive boat. I started with a 22p Bravo 1 and was getting out of the hole great and getting about 54mph top end spinning 5000rpm. I went to a 23p Mirage plus (vents in) and got 57mph at 5000. I m trying to get down into the suggested WOT range of 4600-4700 and pick up top end. I was thinking about trying a 25p mirage but I lost a good bit out of the hole by going to the 23 mirage from the bravo and I dont want to kill it completely. Would I be able to run a smaller dia. prop like a laser in the 25p?

Thanks

Are your numbers gps? If your drive is 1.5 you should be in the 65mph area if your running 5k rpms on hte 23p m+ and 62ish for 22 p b1 Otherwise your getting a lot of slip!!

I would try a 24p b1 next or your rpm gauge is off??

Yes they are GPS numbers. I hve a non mag 454 so I think 5000 is running to high and not making power. I was thinking about a 24p hyro 4 blade. I am trying to get the rpm down to about 4700-4800.

and the Tach seems right, she is screaming at 5000.

If I went with the 24p bravo would I lose a lot of top end and cruise over a mirage+?

The 24 Bravo 1 should give you the better cruise speeds. Labbing the Bravo 1 tends to be a 2-4 mph gain.
Your slip % does seem to be high. Is your gear ratio 1.5:1?
Labbing the 25 M+ will give it planing times similar to the 23 M+ stock.

I do like the M+ on your hull since Mariahs are a little heavy and you do have a 454 which can overpower the smaller blade area of the Laser 2. However, we do have some Laser 2's for testing if you would like to try one.

Brett

Would the 24 bravo bring me down into my WOT 4700 rpm range and maybe pick up some MPH? Do you test bravos or something like a hydro? I am not to familiar with the Mariah hull, it seems I need more bow lift apposed to stern since it's a deep drive boat.

You sure you aren't trimming the drive up too much. My advice would be to start with the cav plate level with the hull and go to WOT. Watch the gps and rpms as you bump the trim in small increments noting the gps and tach as you increase trim until the boat slows down and rpm keeps increasing. At that point you are just over trimmed so go back to the previous drive trim and do your testing at that point.

22% slip is high for a deep drive. I do not believe that a 330 hp motor will pull to 5000 rpm at nominal 10-14% slip on your boat so you may be trimming too much.

Thanks, Thunder I'll give that a shot. I trim until I feel the sliip and then tap back down. Its starnge to me because I never had a deep drive boat before, my trim indicator says I am just under the half line but when I am at the top trailer position the prop is not even close to breaking the water when sitting. My Formula the props were up and out of the water all the way up. I don't rooster tail at all either, don't know if that helps.

Update, I repowered the boat with a 454 Mag MPI fresh rebuild. I took it out and I seem to be really out running the 23 M+. Iwas thinking of maybe going to a 25p M+ but wasnt sure about getting on plane. I was also interested in a 26p Bravo 1, any suggestions.

The Revolution 4 is smaller in dia. than the B1 and have more bow lift. I would try that in a 25" if your 23" M+ is way too small with the 454MAG. Otherwise a 23". What are your numbers with the mag? Remember, the B1 is actually lower in true pitch, i.e. 24" is more like a 23"-23½".

Let's test some propellers.
Call us and we can set it up.

Brett

Thanks Brett, what is a good contact number for you and time to call?

The number in my signature is the best number.

Call anytime.

Brett

@Razor, sorry I didn't see your question in the post. numbers are as follows.

the engine is a 454 MAG mpi gen 6 from a 2007 baja.
My boat is a 22' (21' 10") mariah cuddy.

with the M+ I am turning 5050-5100rpm with a bit of throttle left and speed O said 60ish.

wasnt sure about the hole shot because I always ease it up on place. The Bravo drive seems to be a very deep set drive. when it is all the way up in trailer while in the water the prop is still submerged.

No worries.

As others here, i'm a bit puzzled about your prop slip if your drive sits deep. Have you measured where the prop shaft centerline, trimmed neutral, is perpendicular to the bottom of the boat? How is the condition of your current prop? Dings, bent blades ect. Is the boat bottom clean? No old flaking paint, deep scratches ect. Are your drive 1.5 gear or 1.65? With 1.5 your slip is somewhat high, even for a heavy boat + you say your drive is deep. I would follow Brett on this one. The M+ would be a very good choice, but so will the Rev4. Wether or not your drive is a 1.5 and your prop and bottom is in good condition, I would start with a M+ and a Rev4 in 25" to get some good baseline numbers with new clean props. And when testing, try the LaserII. If it can hook up, it'll be fast.

Brett. As you might have noticed from my earlier post's, I like the Vensura for this size and power of boat. How do you think a Vensura would work on this aplication. I've found it to fit in nicely between the M+ and LaserII. Usually faster than the M+ and sometimes as fast or faster than the LaserII, but with bite similar to the M+, better on occasion. Just a thought.

Carry on:drink:

the bottom is in good shape, no bottom paint or flaking. I am not sure if I need more stern lift to get the deep drive up or what.

prop is a brand new Mirage +