Propeller reconditioning

[Roland Gendreau]

I have an m25xp and the standard 3 blade fixed prop.   I don't have any particular problem with vibration or performance with the prop.   However I was wondering whether it is worth having the prop reconditioned as it is 26 years old.   I don't see any noticeable deformity of the prop blades or any significant dings or worn areas.  In searching thru the message board and wiki, I don't find a lot of discussion on the topic.  So those who have had their props reconditioned, please let me  know what your experience; was there a noticeable reduction in vibration or increase in performance?

Thanks

[scgunner]

     Roland,

        When it comes to props there's no such thing as an insignificant ding. If it's 26yo it's not a bad idea to take it to a prop shop and get it tuned up. They might even be able to put a little more twist into it to improve performance if that's what you're after.

[Breakin Away]

Thanks for starting this thread, as I was going to do the same in a couple of days. I've had my boat for 2.5 years and never pulled the prop. I don't know how long PO left it on without pulling. I borrowed a puller from AutoZone's free loaner program. After 3 days of cranking, tapping, penetrating lube, heating the hub, applying ice cubes to the shaft, I finally got it off this morning. Obviously I'm now looking for suggestions about anti-seize compounds for the future.

I'm in exactly the same situation regarding reconditioning. Condition seems fine, but I'd like to have it checked out professionally just to be sure there are no signs of corrosion problems, etc. I'd love to have recommendations for good prop shops. Near Philadelphia would be nice, but I could go down to DelMarVA or Annapolis if needed.

The prop was clean when I bought the boat, and the yard put on a coat of Pettit "Prop Coat Barnacle Barrier", and I've cleaned and sanded smooth each year, then re-applied another coat. The sanding was thorough (all oxides removed, down to a very smooth gray surface), but was not done all the way to bare metal (since this stuff REALLY bonds strongly to the metal and is hard to remove). Its antifouling performance has gotten a bit worse each year, with about a hundred barnacles at the end of last season (typically near the hub and on the shaft, not as much on the blades). I'm not sure if it's just the water conditions were worse or the fact that I didn't remove it the paint all the way between re-applications.

Bottom line, I'm ready to try something else to reduce hard growth. I have friends who swear by PropSpeed, but at $300 for 200 ml it's a bit rich. I'd be interested in hearing of lower cost alternatives and/or suggestions of prop shops who could do the application. Maybe if they buy the PropSpeed (or alternate material) in bulk and do several props at a time, they might be able to do it for less than $300 including labor.

I'm open to suggestions, since this is a bit more complicated than the outboard props that I've dealt with in the past.

[mark_53]

$300 for a product that doesn't do the job sounds like a waste of time and money to me.  How long do you keep the boat in the water?  Salt or fresh?  How long does it sit unused?  My experience in brackish water has been the longer the prop has not been moved, the more barnacles will collect.  I use no prop coat. Boat was in the water from June through October with no barnacles.  Maybe start the engine to spin the prop at least once a week.  Another option could be another marina.

Oh, and as far as reconditioning goes, I would suspect if your already doing hull speed, you won't see much if any performance increase.

[Breakin Away]

I guess I need to be more clear.

$300 for a product that doesn't do the job sounds like a waste of time and money to me.

Yes, it would. But I never said that. Barnacle Barrier ($30) was OK at first, but not as good lately. This could be due to environmental factors or my improper application. PropSpeed is a different product that has gotten very good reviews from my friends.

How long do you keep the boat in the water?  Salt or fresh?  How long does it sit unused?  My experience in brackish water has been the longer the prop has not been moved, the more barnacles will collect.  I use no prop coat. Boat was in the water from June through October with no barnacles.  Maybe start the engine to spin the prop at least once a week.  Another option could be another marina.

Oh, and as far as reconditioning goes, I would suspect if your already doing hull speed, you won't see much if any performance increase.

My location is in my signature. Brackish water, salinity level varies with rainfall. In the water April-October, on the hard off-season. We've had extremes of drought and floods in the past two years which have caused salinity fluctuations. Due to work and travel I'm away for 6 days at a time, sometimes two weeks. I do spin the prop in the slip if I can't go out.

My bottom paint has been 100% effective at preventing hard growth.

My request for advice has nothing to do with trying to exceed hull speed, which I get to fine. It's only about having a maintenance-free prop that doesn't corrode or load down the engine unnecessarily due to hard growth. It's also about maybe leaving the boat in through the winter at some point in the future, which is why I'd like to do a little better than I am now. I'm open to suggestions.

[Breakin Away]

I just learned about a very new product that claims similar performance to PropSpeed at much lower cost:

http://www.propglide.com/

Searching this site yields no hits. I'd appreciate any comments people here might have.

[Ron Hill]

Guys : I wrote a Mainsheet tech note article explaining why you should take your prop to a shop that uses "Prop Scan".

I also wrote an article pointing out that Catalina installed engines of 21, 23, 30 and 35 HP.  However, Catalina always installed the same 3 bladed prop of 15" x 9" pitch!!!!!!  Most owners with the M25XP engine re-pitched to 10".

I re-engine to a M25XPB and a 3 bladed 11" pitch prop and was very happy. If there had been enough room I would have re-engine to a M35BC engine with a repitched 3 bladed 15"x 12" prop!!

So you be the judge.

A few thoughts

[Breakin Away]

Guys : I wrote a Mainsheet tech note article explaining why you should take your prop to a shop that uses "Prop Scan".

I also wrote an article pointing out that Catalina installed engines of 21, 23, 30 and 35 HP.  However, Catalina always installed the same 3 bladed prop of 15" x 9" pitch!!!!!!  Most owners with the M25XP engine re-pitched to 10".

I re-engine to a M25XPB and a 3 bladed 11" pitch prop and was very happy. If there had been enough room I would have re-engine to a M35BC engine with a 3 bladed 9"x 12" prop!!

So you be the judge.

A few thoughts

Hi Ron, thanks for your comments. Too bad I'm on the hard, because if in the water I'd go out and test my RPMs at full throttle, since I think that's the ultimate test for whether re-pitching is needed. I'll keep that in mind for next season.

But I am a little puzzled why a M35BC engine should have only a 9" diameter prop. Did I misread something?

[Ron Hill]

Breaking : In a number of articles, I wrote (and confirmed by Jerry Douglas) that it is the builder of the hull that determines the diameter of the prop - so the prop does not cause "buffeting" against the hull.

I'm no engine Guru, but I can't believe that an engine that has over 70% more HP needs the same (low torque) pitched prop as the same smaller HP engine!!   

Hope that answers your question. 

A few thoughts

[Breakin Away]

Breaking : In a number of articles, I wrote (and confirmed by Jerry Douglas) that it is the builder of the hull that determines the diameter of the prop - so the prop does not cause "buffeting" against the hull.

I'm no engine Guru, but I can't believe that an engine that has over 70% more HP needs the same (low torque) pitched prop as the same smaller HP engine!!   

Hope that answers your question. 

A few thoughts

I fully agree, but you seemed to be suggesting that a M35B motor should result in reducing the prop diameter from 15" to 9". Either I misread it, or you have a typo.

My other unrelated comment was not addressing prop diameter. It was addressing pitch adjustment of a prop of the manufacturer's selected diameter. The procedure I always heard was to run at full throttle and compare to engine spec, then adjust pitch if out of spec. Obviously certain specialized needs could justify higher or lower pitch, but care should then be taken to ensure you're not under-revving at idle or over-revving at full throttle.

[Ron Hill]

Breaking : I set my low idle @ 1000rpm (why shake your teeth out? and you also get better output from the alternator) I usually cruise @ 80% power about 2400rpm.

Sorry for the 9" typo   

What is MOST important is that you take your prop to a shop that has PROP SCAN!

As Stu usually says "It's your boat" and Ron adds - "It's your prop"!!

A few thoughts

[Roland Gendreau]

Ron

Finding the article you wrote on why I should go to a shop with Prop Scan will take some digging.
To save some digging, can you just tell me why and about how much does it cost?

I found the Prop Scan website, but their dealer locator does not work.  Anyone know of a shop in Rhode Island?

Roland

[Breakin Away]

I found the Prop Scan website, but their dealer locator does not work.

I'm not sure that it doesn't work. It looks like they've lost a whole bunch of dealers, and that there are huge areas of the country with no coverage.

[Bill Shreeves]

Breakin'   I used a very good prop shop, Atlantis Propeller, just across the river from Philly in Cinnaminson, NJ. in 2017.  The owner, Ray was great to work with.  I got my new SS prop shaft from them.  Great to work with and I just dropped off a friends prop to be tuned up a couple of weeks ago.  I heard somewhere that they do the prop work for Cherubini which is very close to them.  BTW, they loan out their "real deal" prop pullers.

http://atlantisprop.com/

[Breakin Away]

...I also wrote an article pointing out that Catalina installed engines of 21, 23, 30 and 35 HP.  However, Catalina always installed the same 3 bladed prop of 15" x 9" pitch!!!!!!  Most owners with the M25XP engine re-pitched to 10"...

Hi Ron, thanks for your comments. Too bad I'm on the hard, because if in the water I'd go out and test my RPMs at full throttle, since I think that's the ultimate test for whether re-pitching is needed. I'll keep that in mind for next season...

Rather than wait for next season, I did a little research. I remembered that the maximum RPM was tested during the survey/sea trial when I bought the boat 3 years ago. (I have not gone anywhere near full throttle since, though I now realize that I should occasionally to knock off any carbon deposits.) I checked the survey report and he noted a maximum RPM of 3800. (I didn't know enough at the time to realize that it might be abnormally high)

The service manual does not say what the maximum RPM of the M35 should be, except that the horsepower is rated at 3000 RPM, and I assume most manufacturers rate their motors at the max recommended RPM. Then, after some more digging, I found a 2004 product brochure for Universal's B-series motors, that said made it clear:

Universal recommends a propeller that will allow the engine to turn 3000 RPM underway at full throttle

So it's pretty clear that my prop should be re-pitched to account for the higher power of the M35B motor, just as Ron suggested. I'll probably give Ray at Atlantis a call to discuss.

...or maybe it's time to think about a feathering/folding prop. Which brand do you guys like best? I want a design that also reverses effectively, since it's critical for dock maneuvering.