Help With Troubleshooting from all You Professionals

[dlochner]

Today I could only manage 1.5-2knts in forward while running at 2200-2500RPM. Barely enough headway to overcome the prevailing wind.
I have a 3-bladed Indigo aftermarket prop (see attached photo). As for your comment on the prop "up against the strut" Last summer's haul out the prop was "up against the strut" I "attempted" to position it where it should have been before the engine replacement. If it isn't, the prop can't be more than 2-3mm from it's intended location.
I expected PropWash from past experience in this boat, there was a lot and feedback in the tiller due to it.
View attachment 237168

Judging from the photo, the prop is too far aft. There is a section of the prop shaft without paint, I assume that is where the old prop was set. The hub on the new prop appears to be shorter.

What is the prop's pitch? How tight is the prop's fit to the shaft? Is the key installed, is it the right size? Where did you buy the prop?

If the prop's pitch is too flat, it will not develop enough thrust. This would also explain the reduced prop walk being experienced.

If the blade area is too small, it will not develop enough thrust.

If the prop is too far from a bearing it will whip, the end of the shaft will describe a circle rather rotate around the center of the shaft. The shaft is not rotating around its centerline axis.

 

[jssailem]

I tried to compile the list of statements about this problem. (see attached).

1. Position of Prop.
   • I believe the prop should be positioned one to two inches from the cutlass bearing on the strut. This is to allow water to flow through the cutlass bearing, cooling it.
2. Prop Fouling
   • Two primary types of fouling occur on props. Marine Biofouling (i.e. Barnacles, weed/algae growth) and Entanglement (i.e. dock lines, fishing lines)

Trying to identify the problem, Prop Fouling is the hope for solving the problem.

When reviewing the posts, missing from the discussion regarding prop fouling is billowing black smoke when the engine is showing 2500-3000 RPMS which is identified in the discussion. Marine biofouling causes friction on the prop blades as the engine is trying to spin the prop. This friction causes lugging, forcing the engine to labor. As more fuel is added to get the desired movement through the water, unburnt fuel is expelled as black smoke. There will be a dramatic increase in drag. The prop blade may deform, generating vibration and an imbalance in the shaft. These symptoms are not identified in the discussion. It may still be a factor or the cause.

Thinking about what else can fit the symptoms:

• a lack of prop wash,
• 2500-3000 RPMs production
• lack of thrust (movement through the water)
• no evidence of lugging

The only thing that comes to mind would be damage to the prop (i.e. a missing blade from the prop). This would account for the above symptoms.

To resolve the mystery, you might use an underwater camera or have someone dive under and inspect the boat.

 

[Night Watch]

I tried to compile the list of statements about this problem. (see attached).

1. Position of Prop.
   • I believe the prop should be positioned one to two inches from the cutlass bearing on the strut. This is to allow water to flow through the cutlass bearing, cooling it.
2. Prop Fouling
   • Two primary types of fouling occur on props. Marine Biofouling (i.e. Barnacles, weed/algae growth) and Entanglement (i.e. dock lines, fishing lines)

Trying to identify the problem, Prop Fouling is the hope for solving the problem.

When reviewing the posts, missing from the discussion regarding prop fouling is billowing black smoke when the engine is showing 2500-3000 RPMS which is identified in the discussion. Marine biofouling causes friction on the prop blades as the engine is trying to spin the prop. This friction causes lugging, forcing the engine to labor. As more fuel is added to get the desired movement through the water, unburnt fuel is expelled as black smoke. There will be a dramatic increase in drag. The prop blade may deform, generating vibration and an imbalance in the shaft. These symptoms are not identified in the discussion. It may still be a factor or the cause.

Thinking about what else can fit the symptoms:

• a lack of prop wash,
• 2500-3000 RPMs production
• lack of thrust (movement through the water)
• no evidence of lugging

The only thing that comes to mind would be damage to the prop (i.e. a missing blade from the prop). This would account for the above symptoms.

To resolve the mystery, you might use an underwater camera or have someone dive under and inspect the boat.

Spot on analysis!
No visible black smoke from the exhaust, no engine lugging, no vibration that would lead me to believe I have an "out of balance" condition.
The more opinions I get the more likely it's fouling that's causing my problem.

Like you say, today I am taking my Inspection endoscope down to the marina and attaching it to a long pole to see if I can get a picture of my prop. If I do, I'll post what I find. As for what the prop looked like at last summer's haul out, please see the attached photo.

 

[Night Watch]

After reviewing my picture from last summer's haul out, I don't believe I pulled the prop up against the skeg/cutlass bearing. But todays endoscope picture will tell the story and if it is up against the skeg, then that's half the story.

 

[Night Watch]

I did contact my diver/cleaner for his attention to the problem. Getting back to the simplest answer, that its fouling, I've failed to mention it could also be from too much growth on the hull (even though I have it cleaned bi-monthly, maybe bio-buildup is playing a role) since last I sailed.

 

[jssailem]

If so, a good wash and a refreshed bottom paint job may fix the issue.

 

[dlochner]

Spot on analysis!
No visible black smoke from the exhaust, no engine lugging, no vibration that would lead me to believe I have an "out of balance" condition.
The more opinions I get the more likely it's fouling that's causing my problem.

Like you say, today I am taking my Inspection endoscope down to the marina and attaching it to a long pole to see if I can get a picture of my prop. If I do, I'll post what I find. As for what the prop looked like at last summer's haul out, please see the attached photo.

View attachment 237186

So, the photo posted on #11 is not a photo of the prop on your boat. That was misleading.

When overloaded diesel engines will billow black exhaust, gasoline engines do not. Gas engines will lug as anyone who learned to drive a standard shift car learned.

Where did you get that prop, it looks like it is on backwards. Usually the straight edge of the blade faces forward. In your photo the straight edge is facing aft.

I think the problem is the prop itself, either a poor design, the wrong pitch, or undersized blades.

 

[jssailem]

It has been my experience to see black smoke and or sooty water and even the smell of unburnt gasoline when an outboard or an inboard water exhaust gasoline marine engine is overloaded and lugging due to a prop fouled by marine biofouling.

Exhaust smoke, be it gasoline or diesel, is a good indicator of problems. Here is a link that may help you with diagnosing your engine health.
8171-boat-engine-smoking

 

[Davidasailor26]

Where did you get that prop, it looks like it is on backwards. Usually the straight edge of the blade faces forward. In your photo the straight edge is facing aft.

I’m not so sure. Looks like mine has the straighter edge facing aft too.

 

[dlochner]

I’m not so sure. Looks like mine has the straighter edge facing aft too.
View attachment 237191

Is the transmission in forward or reverse? On my Maxprop in reverse the the straight edge is forward, in reverse it is aft. I'm guessing the Flexofold is similar.

 

[Davidasailor26]

Is the transmission in forward or reverse? On my Maxprop in reverse the the straight edge is forward, in reverse it is aft. I'm guessing the Flexofold is similar.

On the flexofold the blades fold inward, with the tips folding into streamline with the shaft. They don’t change orientation in forward or reverse.

 

[Night Watch]

So I went down to the boat and got a picture of the prop as it is today.
Also while scanning the underside of the boat it's obvious the real reason for the sluggish performance is the keel is covered in way too much biomass. So, that's the issue, needs a thorough cleaning which I thought it was getting.

 

[jssailem]

Great to get the factual knowledge. Do you now think your engine and prop are doing what they should, and the problem of slow through water speed was due to the hull condition?

I know you were testing the new engine performance, I suspect the hull condition might have become evident if you had attempted sailing.

The picture of the prop suggests there is the design 1-2 inch gap between the prop and the strut/Cutlass bearing. The prop appears to have a bit of slime, but is barnacle free. The slime might just fluff off if you take the boat out and give here a good run. Maybe beers at Port Hudson.

 

[Night Watch]

Great to get the factual knowledge. Do you now think your engine and prop are doing what they should, and the problem of slow through water speed was due to the hull condition?

I know you were testing the new engine performance, I suspect the hull condition might have become evident if you had attempted sailing.

The picture of the prop suggests there is the design 1-2 inch gap between the prop and the strut/Cutlass bearing. The prop appears to have a bit of slime, but is barnacle free. The slime might just fluff off if you take the boat out and give here a good run. Maybe beers at Port Hudson.

Yes, I think my problem is the profile drag from the biomass. The dive/bottom cleaner is coming tomorrow, so, the JWM race around Protection Island scheduled for this Saturday is on the schedule.
All of this "worry" comes about from all of the Over-Winter maintenance, new engine, new water muffler, new exhaust hose, heat exchanger ect..... plus the boat has never had this much biomass hanging off of it since I've owned and I got to second guessing my skills.

 

[Ward H]

but I'm sure the previous owner would have purchased the correct prop for the boat. But I could be wrong.

Trust but verify! I've heard @jssailem say that several times. But you do have experience with the prop so hopefully all you need is a cleaner hull and prop.
Thanks for the additional information.
Looking to hearing what you find with the endoscope.

 

[Night Watch]

Trust but verify! I've heard @jssailem say that several times. But you do have experience with the prop so hopefully all you need is a cleaner hull and prop.
Thanks for the additional information.
Looking to hearing what you find with the endoscope.

See post #35

 

[Tally Ho]

If your boat has a Max-prop (or any other feathering prop), and it was disassembled for any reason (servicing in the off-season for example), it could have been reassembled incorrectly. I did this on my new MaxProp when I first got it. Played around with it in my basement over the winter…did not realize I messed it up somehow. Launched in the spring and at WOT could barely get the boat moving. Ni happen to have taken some photos before launch and I sent them to Fred at MaxProp. He said…”well, I don’t know what you did to it, but the blades are backwards”.

I had to do a short haul and rebuilt the prop on my tailgate while the yard guys went to lunch.

Made a video so I would NEVER DO THAT AGAIN!

 

[dlochner]

I'm sure the previous owner would have purchased the correct prop for the boat.

Never make this assumption about anything on a boat. There are many misguided prior owners out there.

 

[JBP-PA]

No one has asked, did you get a new transmission with your new engine? Did the gear ratio change?

 

[Night Watch]

No one has asked, did you get a new transmission with your new engine? Did the gear ratio change?

My engine is a direct drive atomic 4. This version does not have a transmission in the normal sense.