How bad is my pitted propeller hurting my performance?

[mbhoag]

My prop is a Merc Vengence 13" 3 blade, 18P aluminum (I think) prop (see pics). Its on a 2001 Proline 19 Sport with a Merc 115 4-stroke. Im guessing whole boat, motor, and gear are about 2800 lbs.

Got it on the water today to see how it did at WOT, and top end was 28mph... fairly calm water... No idea of RPM as Tach does not work (new one on order).

I thought I should easily get 32-35 mph, and I am wondering how badly the pitting/corrosion on this prop is hurting me.
Should I replace with another aluminum or Stainless (assuming 13" 18P)

Thanks for the help!

 

[David Young]

Wait until you know what your full throttle RPM's are. You might have something else going on because i agree with you, your boat should do more than 28 mph. Is this a new to you boat?

 

[Sea Rider]

If you haven't tached that prop previously before tach went bad will never know if that prop suits best your boating requirements . Tach with new tach and go from there for a prop maximization to get the full wot revs for that engine as usually loaded.

Happy Boating

 

[mbhoag]

Yes, boat is new to me... this was first run at WOT to find out what problems I might have...
Only problems I have found are Tach (verifed that boat is charging, so rectifier is fine) and live well pump not working (makes noise, but no water pumping)
and then the speed issue / corroded prop

 

[jimmbo]

Vengeance is a Stainless prop. Yours looks like it is a victim of a serious corrosion problem, Galvanic perhaps

 

[mbhoag]

Holy crap batman! you are correct! Stainless prop underneath what appear to be a bunch of "calcium" deposits! Boat came from FL, but I was told it was freshwater only, obviously that is not true... will work with cleaning it with Lime away, toilet cleaner, and maybe muratic acid... will see what I find....

 

[82rude]

Ahh the ever popular never seen salt water fib.

 

[mbhoag]

So far I've tried lime away, toilet bowl cleaner, and for fun... fast orange paint stripper... there has to be something that will disolve the deposits on my prop!

Hints???

 

[jimmbo]

You mentioned earlier Muratic Acid. Both it and most industrial toilet bowl cleaners are Hydrochloric Acid, the TB cleaners just a 4:1 dilution. To me, it doesn't look like a Calcium build up, more like an aluminium plating with bits of other metals. Was this boat moored in the water in FL?

 

[mbhoag]

It originally came from FL to MN, but I was assured by the PO (although I did not really believe him) that it never saw salt water....I think he fibbed a bit...so I don't know if it was moored/docked in salt water, or just run in salt water....but either way it did its thing on this prop. I'm guessing it was docked more than run, as motor & hull are in great shape, but prop...well its seen better days.

 

[mbhoag]

No Title

Well, prop was soaked in a bucket of CLR for a couple hours, then I rinsed it off and back on the boat...
Then up to Minnesota for a week, and had some great results..
With 4 people on board (two adults & 2 kids), she ran at 31 mph, into the wind on choppy water.

Previous best was 28 with the dirty prop with 2 people..

CLR made a world of difference, plus it sounds better and engine does not seem to work as hard.

 

[jimmbo]

Cleaned up nicely. What rpms are you getting with this prop?

 

[Chris1956]

Gee, I never saw a SS prop with that kind of coating. I had a SS prop on my MerCruiser that I kept in the salt water all season in NJ, and never had more than a few barnacles. Maybe it was painted?

Glad you were able to fix it up....

 

[mbhoag]

Don't know RPM's yet, waiting on new Tach Adaptor Module to arrive, Original Tach and Regulator were bad and I replaced them, but Tach Adaptor was bad also...wasn't going to put off a week on the lake because tach didn't work

I did some reasearch on the calcium deposits on the prop, and apparently it is fairly common in parts of Florida, where the boat came from originally... it was new to me as well... when I bought it I thought it was a badly pitted aluminum prop, till someone pointed out that a Vengence is SS....