Chine Walk and Prop Effects?
 

Was talking to the mfg of my 30' triple steped V hull twin (turning in) about the severe chine walk we experience above 70 and he stated the problem was a lack of "matched" props. He maintained that the variance in the Bravo 1 factory props was enough to cause this condition. We are not talking Labbing the props, just making them the same.

THis doesn't sound right. Any comments? I would like to be as informed as I can when I talk to him again.

Re: Chine Walk and Prop Effects?
 

Is this a new boat that was delivered from the dealer with these props? How do the props compare? Are they identical from the factory, or is one a Mirage and the other Mirage Plus? I'm not buying into props on a 30ft chine walker at just 70 MPH. Something is wrong unless you are trimming out way to much. Need more info!

Re: Chine Walk and Prop Effects?
 

Yes, these are both Bravo 28p 4Blades that were on the boat when new. Have had this prob since new and no, trimming out is not the problem necessarily. I have adjusted the trim many times and the problem still exists at speed unless I trim it down so far that it starts to Bow Steer (BAD!).

Re: Chine Walk and Prop Effects?
 

Can you give us a little more information.

year, make and model of boat.
engine specs.( HP and Peak HP RPM)
drive type and ratio
WOT RPM and MPH (gps)

Julie

Re: Chine Walk and Prop Effects?
 

I would start by switching the props and turning them out.

What kind of boat???? Maybe someone else with the same model will chime in.

Re: Chine Walk and Prop Effects?
 

I purposely kept Advantage out of this because they are working with me, I just think their info is wrong but am open to learning. That being said...

2004 Advantage Victory ( open bow); twin 496ho's w/ 1.5 b1X drives; I don't think I have ever gotten true WOT cause of the walk but at 4800-4900 I have gps of 77.8. Have tried the props out but this boat seems to need the bow lift of turning them inward. in either case, it walks.

Have spoken to one other owner of a similar boat (seen in Powerboat) and he said tabs were his only answer to the walking.

Re: Chine Walk and Prop Effects?
 

Do you have tabs on the boat now?

Re: Chine Walk and Prop Effects?
 

No, that's where I'm heading but honestly want to try full hydraulic steering first. I have the Hyd assist now.

Re: Chine Walk and Prop Effects?
 

Sorry I misread. I read Bravo's and was thinking Mirage :(

Re: Chine Walk and Prop Effects?
 

You might want to consider doing both

Re: Chine Walk and Prop Effects?
 

Ahh Yes, but speed costs money - I'm still trying to figure out how fast I can go :-)

Re: Chine Walk and Prop Effects?
 

OK, so do props have much influence in the cause or cure of chine walking????

Re: Chine Walk and Prop Effects?
 

I would think the lack of full hydraulic steering has more influence.

Re: Chine Walk and Prop Effects?
 

There are many reasons why a boat chine walks. One of them is an improper prop selection. Keep in mind props are only one cause of chine walk. There are many, hull design, wrong pitch prop, improper drive height, steering type, etc.

I would agree that your boat needs full hydraulic steering. The lack of full hydraulic steering may not be the cause of the chine walking but it sure isn't helping the chine walk.

Your performance numbers don't seem to work, 4800 rpm @ 77.8 mph works out to a 5% slip. Very unlikely for your boat.

I don't think the chine walk is caused by the props not being matched. Stock Bravo's typically have the rake angle within 1-2 degrees which shouldn't make much difference in the lifting characteristics of the boat.

Matt

Re: Chine Walk and Prop Effects?
 

I don't like this at all...

Re: Chine Walk and Prop Effects?
 

I don't know anything about Advantage boats, except this: I was at a Marina talking to them about superchargers and there was an almost-new 30 foot Advantage there with HOs, may even have been an open bow, and they were working on it, and said that the owner was not at all happy with the way the boat was performing - don't remember any more particulars - I noticed about two months later that the boat was for sale. Does anyone on the Advantage section have the same boat that could help you out? Maybe its the design of the hull. Good luck.

Re: Chine Walk and Prop Effects?
 

Julie, I may have misquoted my rpm/mph in a prior post cause Im at work w/o my numbers in front of me. I have calc'd the numbers before and am at 11% slip at nearly WOT.

Re: Chine Walk and Prop Effects?
 

Just a thought... Are the drives properly aligned, I'm thinking of "toe in/toe out".

That could perhaps also cause the chine walk :rolleyes:

Re: Chine Walk and Prop Effects?
 

LHC,
I have a 23 Wellcraft Nova with a ZZ502/502, no tabs. At 60+,- on gps the boat would start to walk, even in a 6 to 8 inch chop. Sometimes would get scary in 1's and 2's.

I contacted Matt and Julie at Throttle Up. Sent them my Mirage 25 Plus along with hull weight, dead rise, X dimension info, and photos of the drive and transom. TU labbed/tweaked the prop. Top speed is 73 on gps. The prop work done by TU got rid of the walk completely...it's gone. Boat handles completely different. Very solid.

Prop work may or may not cure your problem as our boats are very different. But given the cost of the prop work, it might be the least expensive fix to try 1st.

Good luck - Bill

BTW...thanks Julie and Matt :o)

Re: Chine Walk and Prop Effects?
 

T_W, I have moved the toe in around to find only a little difference in speed but nothing in the way of mitigating the walk.

Kidnova, thanks for the personal info. I am going to add the full Hyd steering first then work the props again. I had them "matched" recently and it seems to be a little better, but not gone.

Good thing I like to "Tinker"

Re: Chine Walk and Prop Effects?
 

Like others have said, props more than likely aren't the problem and not sure if steering will entirely take care of the problem, but will sturdy up any outdrive play, which might cut walking down a bit. I really think tabs are the answer.