Prop Reconditioning, would you?

Had a soft grounding a few weeks back and did some minor damage to one prop, here are the diver's notes:


[FONT=&quot]"Port propeller felt grinded on the edges of each blade. And a few small dings. Starboard's propeller looks perfectly fine."[/FONT]
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[FONT=&quot]I'm not due for a haul and bottom job for at least a year, prop removal is $10.00 an inch plus the same for reinstall. I think my props are 19" in diameter. Prop shop said roughly $400 for the rebuild assuming damage is not too bad. So about $800 all in for one prop.
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[FONT=&quot]We have a long Bahamas trip planned for this summer, probably will put about 800 miles on the boat, some of it (usually about 20%) at "fast" cruise of 14 to 15 knots.[/FONT]
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[FONT=&quot]Boat is currently running smoothly, not having any issues but I know that I would gain some efficiency with a rebuild and Bahamas diesel is really expensive. $800 buys about 125 gallons of diesel over there.[/FONT]
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[FONT=&quot]If I don't do it now I will pull both props at the next haul out and have them done then.
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[FONT=&quot]Worth it?
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After the grounding, do you feel any difference in the boat (vibration, etc.)? Do you still make normal speed / RPM at WOT? And is your speed / rpm at cruise normal?

If all of that checks out normal, I'd wait until the next haulout. But if it's affecting boat performance, I wouldn't ignore it.

I slightly dinged a prop towards the end of this past season. Tweaked the trailing edge of one blade very slightly (hit a submerged piece of wood in reverse while docking). Damage was so slight I couldn't see it, and even sitting under the boat after haulout it took a few minutes of running my hands over the blades to find the damage.

In my case, I limped through the rest of the season (as we were only ~2 months from haulout and would have needed to short haul for prop work due to lack of diver availability). We were speed restricted to slow cruise though. At slow cruise, everything felt normal, speed vs RPM was normal, etc. But if I tried to get the boat up on plane, there was a serious growl (heard more than felt) from the starboard prop and the boat was noticeably slow (both in terms of speed vs RPM and in terms of speed and RPM at WOT). The damage was minor enough not to matter at low speed, but when you spun the prop fast enough and put it under enough load, it was a different story.

I’d do it now. You might not feel anything now, but later?

You don't want any problems in the Bahamas. Getting parts takes forever, and expensive. Do it now and get it behind you.

I would forget about what the diver said.

Would a prop rebuilding be a part of your normal preventative maintenance right now? If not, forget about it.

What are your spare props like? Might be a factor.

pete

Dougcole said:

Boat is currently running smoothly, not having any issues but I know that I would gain some efficiency with a rebuild and Bahamas diesel is really expensive. $800 buys about 125 gallons of diesel over there.

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If you've run it wide open without any issues, one has to wonder how bad it really is.

One of the things I really like about my boat cleaner here in FL, is that he takes before and after pictures with a GoPro camera. Tells me what I have left on the anodes and if I have a ding on the prop, how bad it is.

Please explain how you think your efficiency will improve unless your making a pitch change to both props.

Ted

In the Bahamas, the water is thin enough that there is a good chance of touching them again. Might be best to wait until you return, if you have no operational complaint now.

I’d do it now if for nothing else piece of mind which means sleeping better at night. I wouldn’t be hearing phantom noises or constantly checking for vibration. For $800?

I have not run it at WOT yet, we have a shorter trip planned for late March, I can try it then with plenty of time before our annual summer Bahamas trip to get it fixed if needed. I like the suggestion of trying it out at all speeds, thanks.


I spoke with two prop shops who quoted me the same price. One said he probably wouldn't worry about it, the other said he would do. The one who said he wouldn't worry about it said to do both props the other said just the damaged one.


I banged up my props before a gulf crossing about 10 years ago and couldn't get them repaired until we got home. Burned significantly more fuel on the crossing than I expected. Boat was slower for the same RPM, which is what I chalked it up to. But that was both props and they were way worse than this one.


Pics of the prop would be nice, but my diver doesn't do that. Getting a diver to come to the boat at all is a bit of a chore for me. I am way up the St. Lucie river and a lot of divers don't want to get in the water there due to the pollution from Lake O.

Go to your a shop that does scanning of the props. Then you have a record of what the props look like. We did the props on our last boat and it took out a noticeable amount of vibration. Each prop had one blade out of pitch.

I think its a no brainer. Get them done.

If you can run at WOT and meet rated rpms with no vibration then I don't see the point. The props are not going to fall off. Worst case you burn a little more fuel and if one prop has been thrown badly off pitch you may have to adjust rpms on the good prop. Not an issue.

Note you would have to be blocked for a few days so make sure you're not getting the price for a short haul sitting in the slings. Prop shops are usually backed up and quick turn arounds are rare.

Dougcole said:

I have not run it at WOT yet, we have a shorter trip planned for late March, I can try it then with plenty of time before our annual summer Bahamas trip to get it fixed if needed. I like the suggestion of trying it out at all speeds, thanks.


I spoke with two prop shops who quoted me the same price. One said he probably wouldn't worry about it, the other said he would do. The one who said he wouldn't worry about it said to do both props the other said just the damaged one.


I banged up my props before a gulf crossing about 10 years ago and couldn't get them repaired until we got home. Burned significantly more fuel on the crossing than I expected. Boat was slower for the same RPM, which is what I chalked it up to. But that was both props and they were way worse than this one.


Pics of the prop would be nice, but my diver doesn't do that. Getting a diver to come to the boat at all is a bit of a chore for me. I am way up the St. Lucie river and a lot of divers don't want to get in the water there due to the pollution from Lake O.

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If you are going to do it then I would absolutely get both done at the time. It is amazing how out of pitch a blade or two can be and you may not notice it. But I certainly did notice how much smoother the boat ran after the props were done. I did mine over the winter when the boat was in the barn. I don’t see any way that a diver could have got them off. It was all 2 guys could do to get them off when the boat was out of the water. We had to put a pipe on the long, long adjustable wrench and pull like crazy. And we had the ground to push against.

Larry M said:

I’d do it now if for nothing else piece of mind which means sleeping better at night. I wouldn’t be hearing phantom noises or constantly checking for vibration. For $800?

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Most prop shops will analyze it for $0 and provide a report / recommendations.
I'd do that so you know.
I had both primary & spare analyzed so I had base line data to compare future against. One nothing reqd. The spare (I knew) needed repair before putting into the spares inventory. I (the prop shop) has Baseline data for both now.

My feelings, long trip to an area where service is questionable to almost non existent.
FOr now the very least is test for vibration at full range of speeds. It may vibrate at specific revs but not all revs.

Several times over the years I had an almost invisible bend in a blade that I barely noticed untill it was laid on the flat bench and then it could be seen.

I got the prop repaired and oddly it made a noticeable difference in the vibration level by no longer being there.

Your diver can feel a rough edge? There also could be a blade bend in addition to the rough edges which he likely cannot detect.

Get it looked after.

Here are the scans of my previous boats props, before the reconditioning and after. Note the one blade on the left hand before.

I've found my boat to not be picky about props. Recently, I grounded one prop. It had a significant bend on one blade, curl your fingers over and you will get the idea. I put 75 hours on the prop after damage. I didn't find any difference in fuel consumption, vibration nor speed after the bottom bump.

I did get both tuned up at the first chance, because I experienced how easy it was to bump a prop. I was in a marked channel with a stated depth of 6 feet and I draw 3 feet.

I just returned from the Bahamas and I wouldn't plan on much happening over there. The Bahamas is a hot mess of very nice people with nothing to help you.

Mike

I once had my son in law snorkel under my boat to inspect the prop, I had "dinged" it. He is not a boater.

He reported that the water was murky and he couldn't really see but it felt like the prop was "folded" over.

I pulled the boat and found a small ding.

pete

You can dress the efge of the prop in the water with a file if needed. But you can't always see a tweak in the prop in the water. I hit a deadhead years ago and inspected it in the water with dive gear. Nothing visibke. But it felt "off", slight vibration. I hauled the boat at the first opportunity. As soon as it was out of the water I could see one blade was tweaked. I had it straightened at a prop shop.

Out of curiosity Doug, wouldn't your insurance policy cover this expense? Or maybe you have a high deductible but my policy will cover hauling after striking something and also repairing the damage.