Bravo III XR prop-set
 

Is the new 4-blade forward/3-blade aft lab finished prop-set for the new Bravo III XR drive designed to aid in lifting the bow or the stern? I have a porpoising problem with my current boat equipped with a Bravo III and a 26" prop-set and wonder what effect the new XR props would have on the boat. Thanks!

Re: Bravo III XR prop-set
 

My understanding is that they are producing new props and there will be a new 4B for the front propeller. They are also polish finished with the same prop shaft, the standard.

Julie

Re: Bravo III XR prop-set
 

Yup, I saw a set at the Miami show where the debuted the drive. I was told the drive and new props were designed for heavy performance cruisers that can have big HP like Formula's 400 SS. Julie, any guess on how these props would perform on a single engine, runabout style boat?

Re: Bravo III XR prop-set
 

Not without the specifics. I haven't seen the drive or the props. I am sure in a little time we will start seeing them out there. If you really want some good information I would call Mercury direct as they will have more experience than any of us.

Julie

Re: Bravo III XR prop-set
 

Will do. Thanks! By the way, do you do many Bravo III prop sets? If I keep the set I have, I'd like to get them thinned, balanced and polished and maybe have some cup added. Boat is a 2004 260 Chaparral SSi with the 496 MAG, Bravo III, 26" props, running 52 MPH GPS turning 4,800 RPM. I'd like to get a little more top end out of it if possible without sacrificing cruise efficiency.

Re: Bravo III XR prop-set
 

Yes, we do work B III props. Unfortunately cruise speed and top end are two different goals at two dfferent ends of the torque band of your motor. But we should work towards the happy medium.

Julie

Re: Bravo III XR prop-set
 

Does the new prop-set for the Bravo III XR fit older Bravo III's?

Re: Bravo III XR prop-set
 

I think I heard they would not, but that's not reliable info. I'd like to know the truth as well.

My Searay is heavy and if it'll help get better speed, or better anything without any sacrifice, I'm in, at the right price. :D

In the first season of having a new motor, I'm starting to see some "issues" with my virgin 30p's. I planned on having them labbed once I got a few hours and knew what she does and needs, but at about 45 hours, I have burns on each of the 3 blades on the rear prop. One blade is pretty bad, but I think will be eliminated with labbing. I'm just concerned about why I'm burning holes in this thick clunky rear prop.

Sorry to hi-jack, but below is a pic of the prop and then a close up of the same blade which is the one that's the worst.

Oh, and to show how bad out of true BIII props are, each burn is very different in shape and severity.

Re: Bravo III XR prop-set
 

Is there any cup in the trailing edge of the propeller? Thoses are indeed cavitation burns. You should really determine what is causing them, or I am afraid that the life expectancy of your props wil be drastically reduced.

Julie

Re: Bravo III XR prop-set
 

Julie,

There's no cup at all. They are box stock standard 30's. On another site, this subject came up because others, going from memory, all with stock smaller boats, but big blocks had the burns as well. However, at least 2 of them were labbed and polished (vs. satin finish) and the burn was more of a discoloration. Mine's obviously much more than a discoloration. Also, it seems to be an issue with higher pitched props, like 28's and up.

Could it be from just being way out of true and unbalanced (as most BIII's props are) and being under a heavier load at higher RPM's at a higher trim level? When I noticed it at the degree it is now, it was after a trip where I ran harder than normal and for longer than normal so I'm leaning towards this being from higher RPM's to WOT. This is a Searay 240 Sundeck (deck boat style) that weighs close to 6000# on the water running a 540cid so I don't have any reference points with an applicationn like this. It's kind of a sick and twisted application. :D

Re: Bravo III XR prop-set
 

I was told by the Merc rep at the Miami show that the new props will indeed fit the older Bravo III's.

Re: Bravo III XR prop-set
 

I was wondering when the questions would start coming in?

This was one of the last projects we were working on before I left Mercury Racing. I won't write a book about them but I will give you a little info to clear some questions up.

First, yes they will fit on the old shafts.

Second, Sea Ray Jim, your experience is the sole reason for the development of these new props. Gravitation burn on the B3's whether they had cup or not was a real problem. It started to become more and more evident when B3's started to get coupled to Merc Racing engines. Thunderbird products had a standing order for replacements.

Polished finishes, which they have, do tend to harden the surface and should aid in the prevention of the burns. It looks nice too but does nothing to aid in performance.

The geometry is completely different from the current B3's.

As far as a 4 blade forward prop, let's just say it came along for the ride.

BBLADES will also tweak Bravo 3 propellers. We did quite a few at Merc Racing while I was there. The cupped or the "L" versions tended to show the best results.

They were supposed to be available a year ago........oh well. Some of the processes are out of house and can take more time to QC.

Expect to pay $800-$1000 a piece.

Re: Bravo III XR prop-set
 

Brett,

What would you suggest for props that are already starting to burn like mine? Will properly labbing them eliminate or reduce the burning or is there something in particular that needs to be done to them?

I'm trying to ask questions of Merc. but so far, the only contact I've had luck with in the past, is getting nothing. Same of another "prop" guy who's know as a BIII expert. He's not a member or sponsor here though.

Re: Bravo III XR prop-set
 

There really isn't anything you can do to your props. Sorry.

The only people to talk to about that situation at Merc are either retired, living in heaven, or gone, like me. The rest won't be very receptive to this situation. That's why the new props are being released. I tried to explain it in my last response without getting into the politics.

TO MAKE THIS CLEAR, there isn't anything wrong with the original propellers as far as performance!! They work well. The only down fall is..........if your hydrodynamics create burn on these props, they will continue to do so.

I'm not sure what you are exactly looking for? You should run those props as long as you can and then invest in the new technology. Sorry for giving you the harsh reality.

Re: Bravo III XR prop-set
 

Thanks Brett,

I was just wondering if there was something that might help it. I need to get them labbed and wondered if when the blades thinned, balanced and cup added if it would mitigate the issue. Sounds like the only way to know is to try it.

I'll keep looking out for the new tech. props, and in the meantime, have mine labbed keep looking for used replacements on eBay. :D

Re: Bravo III XR prop-set
 

We will be happy to help you.

Give us a call and we can discuss your options.

Re: Bravo III XR prop-set
 

What's the latest news on these B III props?

Re: Bravo III XR prop-set
 

Bump for grins

Re: Bravo III XR prop-set
 

I firmly believe those prop burns are from the props not being timed correctly.

Jim

Re: Bravo III XR prop-set
 

What is timed correctly?

Re: Bravo III XR prop-set
 

As a blade from the forward prop crosses the top, the rear blade should be installed so that a blade from it crosses the bottom.

Like this...

http://www.teamcrownline.com/albums/...82fe11e752.jpg

Re: Bravo III XR prop-set
 

Yup, that is the correct timing. Merc really never stated in the owner's manuals to time the Bravo III props in this manner but they did indicate to time the old Blackhawk props in this manner. Same timing should apply. Jim knows how to time the props so that is not the reason for the prop burn.

Re: Bravo III XR prop-set
 

Knot's got my back. LOL :D

I was actualy able to prove that timing therory out when I first splashed it in the spring with the new motor. I was getting a definate "splat, splat" sound when trimmed out running at or newar WOT and I could feel it was loosing bite.

I checked and found the props one spline off from being at the clover leaf pattern like Clay posted. I reinstalled and it eliminated the "splat splat" and made a difference I could feel. That was within the first few hours and it's got about 45 on it now.

There are 2-3 others that I know with applications (they are bone stock, but big blocks) that are turning 28-30p props at 4800-5200 engine RPM wiht 2:1 gears, so turning the props in the 2500 RPM range and approaching the 60 MPH range, that have the same burns. One has labbed props.

I think it obviously has to do with the hydrodynamics once the props get past 2000 RPM, speeds are raching the 60 MPH range and maybe more pronounced with the higher pitches.

I've seen Clay's props which are also 30's, but his were labbed with significant cup and I don't believe he ever had any problem and he was definetly spinning them up there and at speeds in the range of 10 MPH higher.

One difference besides being labbed/cupped and having 1.81:1 gears was a nosecone.

I think the hydrodynamics of the BIII just fall apart once you start getting closer to 2300-2400 RPM and reach certain speeds (60 + MPH??) which is why the nosecone works.

Just a therory, but based one the few common threads between similar applications.

(pssst. are you listening Merc.? I'm an ideal candidate for a BIII XR (with the new props) case study. :D )

In the mean time, I have a cav. burned prop with a small stress crack I'm almost certain I'll need to give a proper burial to, so I'm looking for Plan B. ;)

BRAVO III XR Props
 

Here's the reply from Mercury Marine re: application of new XR props on older Bravo IIIs..

Yes the Bravo 3 XR props will fit a standard Bravo 3 sterndrive. As a general rule the odd pitched numbered Bravo 3 XR props run similar engine rpm to the next higher pitch even numbered Bravo 3 props. For example the Bravo 3 XR 27 pitch matches rpm of a Bravo 3 28 pitch.

To find out the size of the original props that were placed on your boat / engine package you will need to contact the boat manufacture. I do not know how well the Bravo 3 XR props will perform on your product vs. the regular Bravo 3 props.


Best regards,

Jo-Ann Lawson
Consumer Service Specialist
MerCruiser Customer Service

I used to work in the service capacity in 1993 at main line Mercury. Answers can be semi canned.

Let me know if you have any specific questions.

B

For what it's worth, I'm digging up this old thread again. :angry-smiley-038:

I just discovered that the standard BIII props have finally been redesigned and are shipping from Merc now.

As far as I can tell, the new standard BIII prop is of course, a 4 blade front and 3 blade rear as the XR's are, but no cup and are the standard matte finish. Pitch should closely match old style BIII pitch unlike the XR which in addition to the extra blade, is cupped. i.e. current 28 pitch would be replaced with a new style standard BIII of the same 28 pitch or with 27 pitch XR's. In my case I don't have any choice but go from the 3/3 30's to a 4/3 28. I've been messing with this for a few years now but now, I'm now armed with dyno results to pin down max RPM better.

With my assortment of burned, cracked, stock, and now dinged 30 pitch BIII's, I'm either to pick out the 2 best out of mine and have them worked and hope for the best, or try the new style, or better yet, XR's. The new style standard 28 pitch BIII's are popping up for sale pretty cheap $500-$800 where the XR's are rare. I'm taking it down to Full Throttle Marine outside Austin this weekend for a little TLC including to address my now skegless BIII. I always imagined :hitit: meant something different! :mad:

I really want to get this done and right this year which means I'll probably end up selling. Seems that's the way things go, get a boat tuned and running perfect just in time to sell. :drink:

The $64k question is, has anyone at this point done any testing or have any experience with replacing their old style with the new standard or the XR props?

When going to XR's go down 1" of pitch if you are in the bottom half of the recomended rpm range for your engine.

4X3 sets have a touch better mid range. Personally I like the performance of the 3X3 with cup added to suit the boat. Thet tend to have the better top end and the cruise increases.

Brett

Thanks Brett. I've really been wanting to try the XR's without buying a set for full pop but they just aren't very common. The new standard 4/3 is surprisingly easy to find for pretty cheap. I'm just afraid the extra blade just won't make enough difference over a 3/3 set like I've been running. The only comparison I have is running a box stock cupped 30 on the rear with a labbed front and the difference was pretty significant. I didn't need to go full trim to carry the boat higher and it just felt like it bit harder.

We'll see. The boat is with FTM right now so once I get it back, if I haven't found something else to try I may give you a call again, and have you work a set of 3/3 30's over for me.

Let me know, we have done a ton of adjustments and Labs on the 3x3.

Brett

Brett, I'll likely be calling you within the next week. Between your comments and the discussion you and I had a couple years ago and comments from others who have switched to either XR or the new 4/3 BIII's, I think having a set of mine worked is the best bet.

I just got off the phone with Bob and I didn't realize he was using you now too. I know others that sing your praises but to hear Bob's comments and what some of his customers has said is pretty impressive. :D As soon as I find a good time to head down to pick it up, my boat will be ready so I have work to do! :drink:

Thanks!

Let me know when they are coming. Also, we will have to go over the current numbers and goals with a fine tooth comb again.

Talk to you soon.

Brett

Don't give up on me. Boat's back and the props are in the garage ready to be packed. I've had a sick kiddo home this week so I'm behind, but the boat's nice and cleaned up! :drink:

NP we'll work together when your ready.

Brett

I haven't been able to catch you by phone but the props are on the way. Email sent as well.

Have a great weekend.

Got it, we'll watch for them.

Brett

Well how did they perform? I've read this thread with great interest, because I have a B3 with 28's and am looking to step up to 30's and was wondering how well the labbed props worked out for you.

Wow, this thread is a blast from the past. I ended up sending my propset to Brett back in the spring of 2006 and he worked his magic on them. They still look and perform great after 260 hours. Interesting info on the standard 4 x 3 sets that are available now.

Jim,
Did you get your props back? I'm in the process of getting some 30p props on my boat and was wondering how well you like the labbed props, and how well they performed.

Sorry, I haven't kept up with this thread and just today got a notice that it had been replied to.

Yes, I did get them back. I haven't had it out as much as I'd like but as far as the work done, they're great. It's really the first real attempt to get my boat dialed in so it's not perfect but I'm still very surprised at the improvements. The only thing I'm fighting is that I had a few hundred RPM I was missing at the top end and it was a ?? whether the first round would get that ROM, maintain the same RPM or lose a little more. So far, it looks like I may have lost 100-200 RPM but everywhere else from idle up actually improved.

So planing is still great (normal load, 4-5 seconds maybe) and even smoother and I actually gained a little cruise speed. However, although it looks like I may have lost a little RPM, WOT speed appears to be about the same.

Once I get more time with them I'll decide if getting what maybe 300-500 RPM on top, is worth what I may trade off. It appears I'm kind of in between pitch with this one and might have done better starting with 28's and going up. When first built, it hit the rev limiter at 5600 with stock 28's in ideal conditions.

I came across some BIII XR's in 28p that I almost grabbed just to try them, which may have been a good application but we'll see. It's performing great and does everything I need plus more and this year is running overall better than ever as I got rid of a few minor gremlins so I'm just trying to get on the water and enjoy it.

If you're going up to 30's, I assume you are under propped with 28's or have added power and can spin a bigger pitch?

That's interesting that the WOT stayed the same or lost and they were labbed..