Prop causing boat to vibrate?

[Kalani 938]

I was just curious if a beat up prop can cause a boat to vibrate when running? I have a Tahoe with a 4.3L V6 Mercruiser and the owner that had the boat before me must have gotten into something b/c the prop seems to be flat edged on one blade and pretty chipped on the other two blades.

 

[mthieme]

Re: Prop causing boat to vibrate?

Yes, a bad prop can cause vibration.

 

[steelespike]

Re: Prop causing boat to vibrate?

Bad prop can also cause premature problems with the gearcase.

 

[Kalani 938]

Re: Prop causing boat to vibrate?

What other things may cause the vibrations?

 

[gcboat]

Re: Prop causing boat to vibrate?

In your case it appears to be all prop problem. However, if you want to do a redneck check on systems pull your prop, hook up the muffs, put it in gear and run it up to 3,500 rpm's or so - no more. If there is anything else out of whack there's a good chance you'll find it. My suggestion is just to pull out the VISA and buy a new prop.

 

[steelespike]

Re: Prop causing boat to vibrate?

What other things may cause the vibrations?

a bent prop shaft, bad iniversals,broken motor mount,a dead cylinder,damaged drive shaft,bad motor coupler.

 

[NelsonQ]

Re: Prop causing boat to vibrate?

a bent prop shaft, bad iniversals,broken motor mount,a dead cylinder,damaged drive shaft,bad motor coupler.

Hopefully its just a out of balance prop, as steelespike said, you could have worse issues.

 

[Kalani 938]

Re: Prop causing boat to vibrate?

That would really be bad if it had worse issues considering I just bought the boat. I know it's possible since it is a used boat, but that would really suck. What are muffs? I'm pretty new to this so try to understand LOL. Are those the things that you hook up to the water hose so you can run it out of water? How do you know what pitch your prop is? Does it say it on it somewhere? I looked at some 4 blade stainless steel props online that were about $275. How much is about average for a new prop? Here is the link, tell me if this would be a decent prop to purchase? It says that this 4 blade prop reduces vibration tremendously. How does this work?

http://hillmarine.com/MercruiserAlphaProps.html

 

[SeaKaye12]

Re: Prop causing boat to vibrate?

You can also take your current prop to a prop repair shop and have it re-worked. (Unless it's too badly damaged...)

This would be a less expensive solution to your immediate problem...and would also allow you some time to research what replacement prop would be best for the way you plan to use the boat.
You will get a lot of opinions here if you give the experts some data: Your boat's weight, engine size; altitude of typical use; WOT RPM with your present prop; if you're primarily looking for the best hole-shot or speed etc...

Your prop should have it's pitch stamped into the metal somewhere.

I wouldn't run it the way it is. Vibration is not good for some very expensive parts.

Chuck

 

[nlain]

Re: Prop causing boat to vibrate?

What you describe on this prop it has to be out of balance and out of balance will cause vibration. The flat spotted blade and the nicked blades will all have different pressures on them in the water which would cause a vibration, another imbalance problem. Take it to a prop shop and get them to repair it. A Merc prop will have the part number and the pitch stamped in the prop housing between the blades.

If you decide to replace the prop there is no better place than Iboats to buy from, you can also check on their exchange program, you buy one prop,try it and if it is not right they exchange it for a different one.

 

[Kalani 938]

Re: Prop causing boat to vibrate?

I think I am just going to replace my 3 blade prop with a new 4 blade prop. I found a good price on this one.

http://hillmarine.com/MercruiserAlphaProps.html

Would this prop do okay or would I need to go a different route? Also, since I am new to this I am going to ask a possibly dumb question! The number that is on my prop reads like this : 48-78120-A40-19P
I take it that the pitch is 19, but what do the other numbers mean? Will I need to buy a hub kit when replacing the prop? Thanks so much for all of the great info guys, I really appreciate it

 

[Kalani 938]

Re: Prop causing boat to vibrate?

Can any of you guys help me out with this purchase? I want to order a new prop, but don't know anything about it so I don't want to make the wrong purchase decision. Thanks in advance for any info

 

[jaxnjil]

Re: Prop causing boat to vibrate?

not knowing what you have, is going to be a crap shoot. your number could mean its a 19 pitch but???????? it should have a clear stamped number and show both dia., and pitch
14.5x19 or something like that
i'v had real good luck and service here at i-boats. till your sure what you have, i'd be carefull ordering

http://boatpropellers.iboats.com/

 

[nlain]

Re: Prop causing boat to vibrate?

That part number looks just like the one on my original Merc prop, 48-78124-A40-23P, mine is 14X23, also if you take your number to this website it will cross to a Turning Point prop. I am not sure on the diameter of your prop, Merc shows 14 and 14 1/2 diameter props with 19 pitch.

http://www.marineengine.com/parts/prop/part_number_prop.html

You will want to check the pricing here on Iboats, I don't think you will beat their prices.

 

[180shabah]

Re: Prop causing boat to vibrate?

You seem to be deadset on a 4 blade SS prop, but what are you trying to accomplish with the change?
It may not be worth the money. nlain gave a link that cross refs turning point props, their hustler is an awsome prop less than half the cost of Stainless. however, until you know exactly what you need from a prop, we can't help you much.

Car analogy:
I got a 17" wheel(it is not a rim), what tire should I put on it?...

 

[Randybeall]

Re: Prop causing boat to vibrate?

With the identification such a problem I would have to suggest taking the prop to a prop repair service and have it identified. They can also tell you whether or not it could be repaired and how much. I agree with the idea of not buying the wrong prop, testing is the only way to get it right. Iboat does offer an exchange purchase program on some props, check that out.

 

[Kalani 938]

Re: Prop causing boat to vibrate?

The reason I wanted to go to a 4 blade SS prop is b/c I wakeboard and I've heard that the 4 blade prop gives you more holeshot and a quicker plane which would be ideal for wakeboarding. I checked the prop again and the numbers I put before were the only numbers that are on the prop. I did notice that two of the 3 blades are flatspotted and the fin below the prop seems to be a littel tweaked to the right. I am about to do the test on it and take the prop off and see if it still vibrates as bad.

 

[BillP]

Re: Prop causing boat to vibrate?

Can any of you guys help me out with this purchase? I want to order a new prop, but don't know anything about it so I don't want to make the wrong purchase decision. Thanks in advance for any info

The best advice I can give you is buy a prop from a dealer who will take it back if it doesn't work. There is only one major retail store chain I'm aware of who guarantees satisfaction on props...and they have 400+ stores.

bp

 

[Kalani 938]

Re: Prop causing boat to vibrate?

Well I did the check without the old prop on the boat and the vibration was definitely less. Why does it sound so much different when you start your boat without the prop on it? How do you know if the place will take the prop back if it doens't work?