Wacked a Log - Questions '99 MC Sportstar

[TheBird]

Hey Ballers,

Texas has not been kind with heat and lack of rain. We are a foot down and suddenly things you would never touch are prepared to create a bad day.

 

I wacked a submerged log, did a number on my Acme prop but was able to get it fixed up and ready for another day. Got the prop re-installed but hearing a difference in the engine. I try to think take pride in my attentiveness to boat and car noise that differs from the normal. The engine sounds different and there appears to be a harder/larger? wake being thrown on typical pass lengths. Not a lot of vibration, where someone jumping into the boat, probably wouldn't notice but it does have a slight buzz at take off speed. Shaft looks straight on inspection by eye with not tilt or favor to one side on entry into the hull, strut, rudder, fins looks straight as well.

 

Should also mention that the RPM rates are the same as they were pre whack and top speeds seem to be the same.

 

Just wanting to get some thoughts before I call out the technician, $100 service call and "Break Out Another Thousand"

 

Best of luck, chase buoys and not stumps,

 

Bird

Edited August 28, 2023 by TheBird

[Ski_Dad]

I'm not a big fan of fixing CNC props - i would at least try another known good prop to see if it's just the prop and then buy new one for your main prop.

[MDB1056]

Did the engine immediately stop when the log was hit? Agree with above to first try another prop as easiest step 1. If the same, chance shaft or strut was slightly affected and not seen with naked eye.   

[TheBird]

6 minutes ago, Ski_Dad said:

I'm not a big fan of fixing CNC props - i would at least try another known good prop to see if it's just the prop and then buy new one for your main prop.

I have an old brass 4 blade that came with the boat, I will maybe give that one a try over the upcoming long weekend. What's the thoughts on the CNC re-work and what has made you fellas not a big fan?

[scoke]

Been there and done that. Had an Acme 422 that we bent the tip on. Sent it to Acme for a rework as we ran it on a 196 with the 343 motor and zero off.

 

That boat was never the same with that prop and the prop was never the same. You could sense something was "off" or otherwise. I called Acme and they admitted that the prop will never be the same as it is. It's laser cut and the tips and cup of those props is laser thin.

Heck, I think a high hour acme prop does not feel the same as a brand new one. 

 

I had a 99 Sportstar for 3 years. Hell of an awesome boat. If I'm in your shoes, i'm putting an OJ or another equivalent prop on it and testing that.

What color is your boat? I see your in Texas, where did the boat come out of?

 

Edited August 28, 2023 by scoke

[BraceMaker]

Looking straight isn't really good enough very small run out issues will thrum badly.

It also sort of sucks because there isn't an easy way to mount a dial indicator (nothing magnetic under the boat) but if you have a decently sized C-Clamp you can clamp a dial indicator to the strut.  I usually pull the prop and measure behind the strut just in front of the prop, again in front of the strut and then a final time inside the boat boat where you can typically reach if you have a mag base stuck to the transmission.

Or if you have a set of rollers obviously taking the shaft out is best.

I bet your shaft has a bend in it and that bend is sometimes inside the boat.

 

 

[TheBird]

43 minutes ago, scoke said:

Been there and done that. Had an Acme 422 that we bent the tip on. Sent it to Acme for a rework as we ran it on a 196 with the 343 motor and zero off.

 

That boat was never the same with that prop and the prop was never the same. You could sense something was "off" or otherwise. I called Acme and they admitted that the prop will never be the same as it is. It's laser cut and the tips and cup of those props is laser thin.

Heck, I think a high hour acme prop does not feel the same as a brand new one. 

 

I had a 99 Sportstar for 3 years. Hell of an awesome boat. If I'm in your shoes, i'm putting an OJ or another equivalent prop on it and testing that.

What color is your boat? I see your in Texas, where did the boat come out of?

 

Exactly what I am feeling. Frustrating to get a prop, whack it, and it’s got that noticeable “what’s wrong”. Suppose that’s what I should have expected. 
 

The boat is red and white and came out of Texas as well. Got hold of it last year. 

[LeonL]

I just don't think you can repair a CNC prop.  It was computer machined and you can't do that over.

[jpwhit]

The slalom course at my lake house is very shallow at one end. So I damage props now and then. I’ve probably been through 4 props in the last 4 years. I’ve had 3 of those repaired by OJ for free when buying a new prop. They are never like new and I only use them while waiting for a new one to arrive. I sent one of the rebuilt one back to OJ to see if they could make it better. And it improved some, but still not like a new one. 

My theory is that the reworking process changes the tensile strength of the metal. Typically one blade takes the bulk of the damage, so gets the most rework. That causes that blade to flex differently under heavy load than the other blades. The reason I think it’s related to blade flex, is because the reworked prop feel the worst under heavy acceleration. My best reworked props feel fine running at speed without a skier. But they don’t feel good under load. 

[Bufootin]

High probability that your strut and shaft are toast it you hit that log at speed.  You can remove the shaft and have a machine shop check it.  Tolerance is .003 out of round so very tight tolerance.

[RichardDoane]

Unbolt the shaft coupling from engine and see if the alignment has changed. If the strut/shaft has moved you’ll see it in the fit of the loosened coupler. Might take a feeler gauge to tell. 

Edited September 1, 2023 by RichardDoane
Typo

[teammalibu]

Edited September 5, 2023 by teammalibu

[S1Pitts]

@teammalibu That picture is amazing. Was it a 3 or 4 blade prop? Almost art.

[ETskier]

Aluminum outboard prop maybe?

[Hockdog]

That should polish out