Prop question

[Helmsman]

Carver 33 SS 2006 with Crusader 6.0 MPI engines and ZF63 transmissions.

We had a touch and go. Afterwards, we were getting a vibration at about 2100 RPM’s in the starboard engine. A friend of mine pulled the starboard prop. I got the prop repaired. The boat ran fine after that. However, I only got it up to about 2700 rpm’s.

(I have removed one of the props before (can’t remember which) chasing down an RPM problem which turned out to be water in the fuel filter).

Later in the fall, we hit something under the water on an extended trip up the Tennessee last fall, and I noticed a (new) vibration at about 3100 rpm’s. I stopped at a marina, they pulled the boat, gave the props a once over, put the boat back in the water, and then told me both props looked good. Back in the water, the issue still existed.

So, I bought a set of new props from Delta (Michigan Wheels) 22 x 22 that are the exact replacements. I looked for used, but couldn’t find any. This spring, I had a diver replace the old props with the new props. The ride is a whole lot worse now, with vibration from 2100 to 2400 rpm’s. The vibration is bad enough that the power cable locker is rattling louder than the engines. You can feel the vibration in your arms and legs and the steering wheel. there is a vibration at lower rpm’s. It smooths out after about 2500 rpm’s. I did not check while underway to determine which side was making the vibration.

So, I took the old props to the repair shop. This shop is highly thought of and repairs props around the southeast. The guy running it started the business when he was 19 (now 62) and has seen just about everything. He also scans the props with what I assume to be is a propscan device. Sure enough the RH prop is bent. He and the diver both told me that the starboard prop is the RH prop.

So, One of my questions is this. I have a picture of the prop from either the first time the prop came off (fuel issue- could have been starboard or port) or the second time it came off (starboard prop repair last fall). The picture clearly shows that it is the left hand prop. Can anyone tell me whether the starboard is the RH prop or the LH prop? What happens if the props are reversed? Does the boat go in reverse when you put it in forward? we are putting the props back on Tuesday or Wednesday of this week and I would like to have an independent answer to the question prior to doing so.

I Had spoken with a top mechanic on the lake here who advised these steps.

Pull the new and replace with the old after the prop repair shop gets them “perfect”. Use new keys. he said that you should always use new keys. That will happen this week.

If that doesn’t fix the issue, then replace the cutlass bearings (Anyone know if there are one or two on each side? I am thinking there may also be one where the shaft goes through the floor along with the one further astern just behind the prop)

If that doesn’t fix it, repair/replace or check alignment on the shaft(s).

If I still have a problem, it may be the transmission is the problem.

Does this sound like a reasonable approach?

Any help would certainly be appreciated.

[Midnightsun]

If the props were installed backward you would go the opposite direction you are trying to go so they were on correctly. He said the prop was bent so definitely a cause for vibration for sure. I would start there and not worry unless the vibration problem persists.

[bud37]

I can only add....did anyone check the shafts for true at any point in this ?

Your mechanic is right about the new key, also lapping/fitting the prop on is advised for a proper fit by the prop makers. That step may not be possible with a diver.....you can always ask I guess.

[Helmsman]

Source of the post I can only add....did anyone check the shafts for true at any point in this ?

Your mechanic is right about the new key, also lapping/fitting the prop on is advised for a proper fit by the prop makers. That step may not be possible with a diver.....you can always ask I guess.

No, the shafts have not been checked for true. That will come if I have to get it pulled. The mechanic advised the steps to take. How is a shaft checked for true?

What is lapping/fitting?

[Viper]

Source of the post I can only add....did anyone check the shafts for true at any point in this ?

+1
You're beating yourself around the bush and probably spending more money than needed with repeated service calls if nobody checked the rest of the running gear after she was grounded. That means, dialing the shafts, ensuring the struts are still straight and aligned, ensuring the rudders are straight, condition of strut bearings, etc. These are musts after a grounding. If all they did was check the props, then you have to question competency. The slightest bend in a strut will put the engine alignment out, bad strut bearings and bent shaft will cause the shaft to wobble. Not only will this cause vibration but it will have detrimental effects on your transmission.

A poor running engine can cause a vibration, chances are though that you'd hear the effects of that in transmission chatter at lower rpm. Not that the chatter doesn't exist at higher rpm, it's just way more difficult to hear with the increased engine noise. As rpm increases, the harmonics change and could result in a smoother tranny operation. The same holds true for a bad alignment or running gear...no vibration in a certain rpm range but very noticeable in others. I think given you had a grounding, the running gear is where you want to focus on.

Starboard side should be the RH prop.

[Helmsman]

Source of the post

Source of the post I can only add....did anyone check the shafts for true at any point in this ?

+1
You're beating yourself around the bush and probably spending more money than needed with repeated service calls if nobody checked the rest of the running gear after she was grounded. That means, dialing the shafts, ensuring the struts are still straight and aligned, ensuring the rudders are straight, condition of strut bearings, etc. These are musts after a grounding. If all they did was check the props, then you have to question competency. The slightest bend in a strut will put the engine alignment out, bad strut bearings and bent shaft will cause the shaft to wobble. Not only will this cause vibration but it will have detrimental effects on your transmission.

A poor running engine can cause a vibration, chances are though that you'd hear the effects of that in transmission chatter at lower rpm. Not that the chatter doesn't exist at higher rpm, it's just way more difficult to hear with the increased engine noise. As rpm increases, the harmonics change and could result in a smoother tranny operation. The same holds true for a bad alignment or running gear...no vibration in a certain rpm range but very noticeable in others. I think given you had a grounding, the running gear is where you want to focus on.

Starboard side should be the RH prop.

Thanks, Viper. I will go through the process. The problem is that the marina I had the boat pulled at one lake north of here last year held the boat for two months, and really didn’t address the issue. The only one on this lake screwed up replacing shaft seals two years ago after a 4 month delay in addressing it. They got it right finally, but the service was terrible.

The mechanic I am talking to is highly respected here. He was planning to come up last Tuesday to help diagnose the issue and was the one who suggested the course of action. Unfortunately, he was a no show and I never received a call back from him.

I am very aware that I am throwing money away at this point. But, I am stuck with going through the process as he laid out, with or without his help. I will need to take the boat in to get it addressed. My first step will be to get the old props back on, because there was a huge difference in the vibration with the new props on.

With the old props I had a “beating” sound at 3100 rpm’s. With the new props there was vibration all the way up to 2400 with the worst at 2000 to 2400 rpm’s and as stated

I am assuming the new props were bent in shipping, never checked in the first place, or the diver screwed up the install. He didn’t use a new key on the starboard, and said the port was missing its key which he replaced (though he acknowledged he may have lost it in the water). He stated that the port was extremely tight to get on. Raises questions with me.

After I replace the props this week, if I am still experiencing the vibration, I intend to call both yards, see which one can do the work, and when they can do it (based upon previous experiences numerous commitments will be made and not followed through) and pay the piper.

After that, I will probably get out of big boating because I have learned through this, the inverter install, and several smaller projects, unless you become an expert in boat mechanics, you are putting yourself at risk by using the available help on these lakes. This will be another season gone, so I have effectively been able to use the boat 2 out of 4 seasons. It is a shame but it is what it is.

With the number of large boats around here, it is surprising how poor the service is.

[bud37]

I am assuming the new props were bent in shipping, never checked in the first place, or the diver screwed up the install. He didn’t use a new key on the starboard, and said the port was missing its key which he replaced (though he acknowledged he may have lost it in the water). He stated that the port was extremely tight to get on. Raises questions with me.

Yep , that is a red flag......here is a link to the fitting process.... new props should be fitted properly the first time.....


https://marinehowto.com/lap-fitting-a-propeller/

[Helmsman]

Source of the post I am assuming the new props were bent in shipping, never checked in the first place, or the diver screwed up the install. He didn’t use a new key on the starboard, and said the port was missing its key which he replaced (though he acknowledged he may have lost it in the water). He stated that the port was extremely tight to get on. Raises questions with me.

Yep , that is a red flag......here is a link to the fitting process.... new props should be fitted properly the first time.....


https://marinehowto.com/lap-fitting-a-propeller/

Thanks Bud. I will watch when I get back in.

[Helmsman]

Source of the post I am assuming the new props were bent in shipping, never checked in the first place, or the diver screwed up the install. He didn’t use a new key on the starboard, and said the port was missing its key which he replaced (though he acknowledged he may have lost it in the water). He stated that the port was extremely tight to get on. Raises questions with me.

Yep , that is a red flag......here is a link to the fitting process.... new props should be fitted properly the first time.....


https://marinehowto.com/lap-fitting-a-propeller/

Interesting discussion. I never considered the shaft to prop mating. Certainly might be the problem with the new props. I should get the old ones back tomorrow and will get them back on by Friday, hopefully.

[Viper]

It's a must under some circumstances. The scary thing is how few techs even know they're supposed to do it at all.