Bravo 3 prop selsction

[Offthepath]

I have a new to me 2006 Crownline 240 EX with the 350 MPI and Bravo 3. Its a pretty heavy boat with a dry weight of 5k. Generally we use the boat between 3700 ASL to 6000 ASL. I am looking for a prop that will give us a little better spectrum of performance across the elevation uses. I feel the boat should plane faster, and getting some more cruise and WOT MPH would be nice.

Currently, it has a 22p prop and all the testing as been done between 3700-4500ASL. Cruise at 3500rpm is 27MPH and WOT is 4900 at 42mph.

I am looking at Hill's 4x4, a Mercruiser OEM 4x3 or possible sending the existing prop off to someplace like Bblads. Bblads claims they can get some decent performance gains out of the factory 3x3 props.

Does anyone have experience with these three props? I'm leaning towards the Hill, but based on what I read you loose top end and I dont feel like the boat is very fast to start with, but a better cruise speed would be great.

 

[alldodge]

Assuming a 2.0 drive your slip is 17% with the current prop. Having Brett at bblades thin and lab the prop can reduce some drag, but being right at optimum rpms there isn't much to work with. Lab (polish) the prop makes the blades thinner (less drag) but also makes then easier to crack (less metal). If slip goes down, rpms in most cases also is reduced.

If you go 4x4 it would mean 20 pitc.

More blades more drag
More blades more lift
Cupping a prop gives it more bite going forward, and less going in reverse

Have not tried 4x3 (Merc xr) but have tried hill 4x4

The XR props are done in odd numbers so you could go with 21, which would get you out of the hole quicker, but that is a maybe. The 4 blades in the front is more drag.

The extra lift may help but can also cause proposing, all depends how the boat reacts. My guess is with only making 42 mph this may not be an issue, but just guessing

Good think with hill is they will go back n forth letting you change props, and only cost is for you to send the props back, they pay hip to you.

You can buy the hill props from Brett, but he changes a 15% restock

 

[Scott06]

I am looking for a prop that will give us a little better spectrum of performance across the elevation uses. I feel the boat should plane faster, and getting some more cruise and WOT MPH would be nice.

I'm leaning towards the Hill, but based on what I read you loose top end and I dont feel like the boat is very fast to start with, but a better cruise speed would be great. [/QUOTE]

youre not going to get both better acceleration AND higher top speed unless you put a bigger engine in. Go down in pitch / get the 4x4 set up and you'll get better acceleration and likely lower planing speed. Prop up in pitch you might get a little more top end and lower WOT rpm, but acceleration will suffer.

 

[Offthepath]

I guess I should add, the drive is a 2.2 ratio.

Any idea on how much top end I'd likely loose going with the hill 4x4s? Would the 4x3 split the difference, better acceleration while not killing top end?

 

[alldodge]

With a 2.2 drive
WOT is 9.5% slip and is good for the hull

At 3500 rpm 27 mph your at 18.5% slip so the hull isn't up on full plane. I'm guessing but your best cruise may be closer to 3800 and maybe 32mph. If you get 32 at 3800 then slip is down to 12%

Again more blades more drag, but going to a 20 4x4 will keep it about the same, but may help with cruise. In most cases you can find a used set of 3-blade 20's and have them cupped

Otherwise call Hill and talk to them, they will work with

 

[Offthepath]

Getting up on plane and hole shot is what I'd like to improve the most. Would staying with the prop I have and adding trim tabs help noticeably while still keeping the top end speed the same?

Thanks

 

[alldodge]

Tabs will get you up easier and in most cases are a welcome addition.

IMO

PRO
Planing is somewhat easier
Levels the boat while on plane
People don't have to be moved around so much to keep level
Can be used to lower bow for increased visibility
Can stay on plane at slower speed

CON
They add resistance, and at lower speeds motor will work harder
With insufficient power they should not be placed full down to take off
Top speed can be achieved only by bringing them full up
Can be damaged if not full up when trailering or on boat lift

 

[blamtro]

I bought the Hill Marine and had to use their exchange program. Started with B3 factory 26p, first tried Hill 24p, then needed to trade for Hill 22p. Super happy with them.