Prop Tip Damage
 

Guys,

A couple weekends ago, the wife and I were out on our not-so-favorite lake, Caesar Creek, which is an overgrown mud puddle that suits the purpose when we have a day to work with. As it happens, I haven’t really figured out how to get a reliable reading out of my depth finder, and I wandered a bit too close to the bank (I guess) in a no wake area I wouldn’t have thought I really needed to worry about it. I felt the prop chewing on something, so I turned away from the bank, tapped reverse and got away from whatever it was. After backing out a ways, I shut it off, raised the outdrive all the way up, reached down and felt the prop for damage. Not feeling any, we went about our way. After clearing the no wake zone, I brought it up on plane, then leaned into it. This is the fastest I’ve seen this boat run. We were tickling 78MPH at about 51-5200RPM. Previously, the highest I’ve seen the tach was just north of 5000, which put us at 76, maaaaybe 77.

After getting the boat back on the trailer, I visually inspected the prop, finding this:


https://cimg1.ibsrv.net/gimg/www.off...271ca36f3.jpeg
https://cimg3.ibsrv.net/gimg/www.off...44dfdd525.jpeg
https://cimg4.ibsrv.net/gimg/www.off...151e54ed6.jpeg
https://cimg5.ibsrv.net/gimg/www.off...d6e602193.jpeg

Two of the prop tips (1 and 3, so to speak) are flared out, ever so slightly, with no cup at that transition area between leading edge and trailing edge.

This last weekend, we were out and I was able to squeeze 5400 out of it (Whipple stage 2 tune, 5450 rev limit), but we were weighed down a bit more than normal, with some friends’ cooler in our cuddy, along with ours (they were in another boat at the moment), and I didn’t stay in it long enough to wring out the GPS. No other handling behavior changes that I can pick up on.

Am I nuts to think the elimination of that cup right at the tips loosened up the prop just enough to let it spool up that much?

Thanks. Brad.

Not the recommend way of tuning your prop but it seemed to work! LOL.

Prop 'tuning' is Black Magic, and you may have introduced JUST enough of a variable to do the trick!

Did you take a gps position of Speed Rock so some of us can have it do some magic for us too ? Lol.

Yep, my prop tips are slightly massaged over on purpose. Got a couple hundred more R's out of them. George did the work. Cool Breeze Marine, Osage Beach MO

SB,

I did not. But I know "about" exactly where it is. If anybody wants to give it a whirl, I can point you right to it. :angry-smiley-038::ernaehrung004:

Thanks. Brad.

Helmhurst,

This is what I was wondering. It makes sense, but the gurus might already know it or know better. Not that I stand to "teach" Brett, or George, or anybody else in the industry, how to tune props, but, if I've happened across a tuning feature that my boat likes, why not propose a more controlled application of it when/if sending a prop off to someone for tuning?

As I said... Prior to, I could put the throttle on the firewall, trim the drive out as far as I wanted to risk it, and all I'd get was 5K RPM. That's it. Now I'm seeing 5400 if I trim it out far enough, which isn't anywhere near where I've had it trimmed out to in the past. Something changed, and the prop tips are all I can think of. The funny thing is, it's just the two opposing blades that were dinged. The other two, while they've got some "burrs" on the non-working edge, they are not deformed in any way (that I can tell).

It's just weird. And I'm hoping someone can honestly tell me, "Oh, yeah. I've seen that before".....

Thanks. Brad.

So the question is, are you going to leave it that way?

would be interesting to have the props scanned on a CMM and see how far off the blades are to one another :)

About 15 years ago I hit a submerged wing dam on the Mississippi river. Without checking the prop yet, I run the boat up to WOT to check the prop and it was literally 2-3 mph faster than usual. Like you, the boat felt quit a bit looser, but ran great. When we pulled the boat out, I could not believe how badly the prop was chunked up! Should have never fixed it! Its a Bravo 1 prop and I never did try anything else except a B3 drive for a couple of years. The B3 was definitely looser but no faster. I am thinking a REV 4 is what I should be trying. Bottom line is that I completely believe ya Brad!