Brad Christy

Guys,

So, I'm considering a prop offered to me by a fellow OSO member. I am curious what the real difference is, specific to my boat.

PowerQuest 280 (single step), 496HO/M1 Procharger/Whipple stage 2 tune. I am currently running a stock Bravo1 28P. It planes well and rides nice with a top speed around 76 right at 5000RPM. I have noticed that I have to trim it out further than I think is appropriate to reach that RPM, and usually end up dancing a line between top end and porpoising. It seems like the boat would like less stern lift at WOT. The FS is supposed to provide that, but that should increase planing time, too. Just wondering what others' observations have been.

Thanks. Brad.
(937)545-8991

Knot 4 Me

From Teague's site:

With the introduction of the four-blade Bravo FS, bass, multispecies, bay boat, and center-console applications have realized much quicker planing compared to three-blade propellers. In addition, the Bravo FS provides a much smoother ride by improving the angle of attack. By switching to a Bravo FS, the engine can be raised as much as an inch, getting the most performance of any engine application and improving the driving experience. For some stepped hulls, the Bravo FS offers more bow lift than the Rev 4, improving ride quality because the boat rides on the steps correctly.

We’ve added four new models, ranging from 34-inch to 37-inch in pitch and designed specifically for our 4.6L V8 300R FourStroke outboards with the right-hand rotation: 1.75:1 gear ratio Sport Master gearcase.

• Compared to a three-blade propeller, the shortened barrel of the four-blade Bravo FS provides the same impressive bow lift, with a slight degree of added stern lift.
• In light to medium chop, the Bravo FS offers a smoother ride.
• In rough conditions, four blades improve the angle of attack with the motor trimmed in. This means the boat can stay on plane at lower speeds.
• Greatly improved hole shot and midrange fuel economy
• Four blades allow for higher running heights and improved efficiency over a three-blade thanks to less drag from the gearcase in the water.

smokediver

BBlades labbed a Bravo 1 for me and removed half of the diffuser ring , much like an fs. It really squats the stern down and very little trim is needed. I have a non stepped 24 degree hull for reference.

kornegle

I tried about 5 props on my 2400 Checkmate / 300R combo. One was a 24P Bravo FS and another was a 26P Bravo 1. The engine was not quite broken in well yet, and then the Bravo FS ran around 73 mph @ 6350 rpm with 9.5% slip. The 26P Bravo ran 70 mph @ 5800 rpm with 13.4% slip. What surprised me the most was that the 26P actually planed just as fast or a bit faster than the 24P FS prop. The 24P was very good coming on the plane but the 26P with the diffuser was slightly better even with more pitch. There was less chine walking trimmed out at WOT with the 26P Bravo. The FS did lift the bow better, or perhaps I should say I used more trim to lift the bow with the 26P Bravo. I think if I had a 24P Bravo 1 at the time, it would have run within 1 mph of the FS but that is just a guess. Today I have 130 hr on the engine and it turns that 24P Bravo FS to the soft limiter at 6450 rpm, and it turns a 24P ProMax to 6350 - 6400 rpm @ 76 mph. Not sure your heavier boat with a more powerful sterndrive would react the same, but I think less diffuser length will be less drag and slightly faster.

im MartinB

Transom lift speeds up time to plane. Transom lift creates more wet bow area which leads to reduced top speeds. Quick solution to reduce time to plane is a bag full of hundred dollar bills.

25Orion

I’ve found the lack of the diffuser actually allows more natural bow lift, where the diffused props help lift the stern, at same time faster plane.

For the OP I’d suggest trying a Bravo 26, or possibly have your existing 28p labbed down to a 27p leaving full diameter and diffuser. If it runs better but you still feel the need is than suggest as a second alternative to trim approximately half the diffuser.

Brad Christy

25Orion,

I'm actually planning on going the other way. My hope is to secure a second 28P and have my current prop repaired (slight tip deformation from an unfortunate shallow water incident since my original posting), labbed and pitched UP to 29. Labbing is supposed to garner a couple hundred RPM, and an increase in pitch reduces RPM. The hope being that the give-n-take will result in a better top end without any loss in performance elsewhere or any increase in RPM.

I have also come to the conclusion that my thinking on stern lift has been backward. The RPM is coming up while trimming due to reducing the blade engagement with the oncoming water, and an INCREASE in stern lift would actually aid in reducing porpoise, faster planing, etc...

Thanks. Brad.

25Orion

well you’re original post spoke of over trimming, if you’re over trimming to gain RPM, you’re just creating slip not propulsion.

Brad Christy

25Orion,

While I wholly agree with that, I can also watch the GPS climb as the RPM increases. My hope is to get a bit more top end without sacrificing the rest of the RPM range. If I could get a bit more stern lift, I can trim it out to get there without the porpoising.

Two points of note:

1) We recently got to really wind the boat out in near perfect conditions: Coolish, dry weather, “flat” water with about a 6” consistent wind chop. We saw 78MPH at ~51-5200 RPM. According to BBlades’ prop slip calculator, that represents <15% slip.

2) The “OSO member” I spoke about wasn’t a member at all, but someone who’d gleaned my ph# from my posts and was trying to scam me. Which is why I don’t include it in my posts anymore. FWIW….

Thanks. Brad.

Gimme Fuel

Brad,

FWIW I trimmed the diffuser on my 30p Bravo I's that ore on my 380 PQ, as everything I have done to reduce stern lift has been a positive gain on my boat, however not so much with the diffuser removal. Boat won't get on plane without extreme measures and just blows props out as boat begins to level out. When I did get on plane, props had a lot of slip and lost 5-6 mph. Just had diffusers welded back on.

With the high x-dimension that these hulls have, I don't think it will work for you either.