Propeller reconditioning

C

Carvervirgin

Member
Member
Joined
Jan 4, 2012
RO Number
32836
Messages
323
My Carver motor yacht is 12 years old and I am the 3rd owner. As far as I can tell the props have never been reconditioned. They do not show any blemishes or obvious issues and the boat is solid and without concerning vibrations under way. When should you have the props reconditioned? How do I know it is time?
 
As Mr. Houseboater notes, the propellers will let you know when its time.

Its not an age issue and you likely have the boat out each year and someone would notice if you've buggered them up.
 
If you are able to reach WOT and have no vibrations don't do anything.
Rob
 
There are more issues with misaligned or out of tune props that just shaking or RPMs. If you are wondering if your props need some tuning take them to a PropScan center along with the specs for your boat including current WOT, engine and trans specs. They will put your props on the computer and tell you if tuning will achieve any performance improvements.... and the scan is free. My Carver didn't have any vibrations or other indicators until I installed a Floscan fuel monitor and saw that one engine was burning fuel at a rate much higher than the other. Propscan found one prop pitched more aggressively that the other and corrected it.
 
John,
As an FYI when I bought my boat the props were dinged up. I sent them to a prop scan place in NH. Shipping was 40 buck or so each way, and the scan and repair was a little over a thousand bucks.
I would not worry about it if you are not seeing any problems.
Also, that same year I hit a rock in smugglers harbor, 500 bucks down the drain in a second. I did not send it back, instead had a welder in Alburg repair it for not much money. I could not tell the difference in performance.
 
In this case I have to disagree with the dont fix it folks. Propscan testing and adjustment can make a big difference in speed and economy,testing is free. In my case there were no symptoms yet tuning the blades to proper curve across the entire blade added 1.5 mpg at wot and decreased load at cruise. On trawlers or slow boats it may not matter but somehow efficient props should improve any boat.

Have them tested and see what the report says.
 
Mikeh has it right! Props on my tolly did not show any vibration but I could not get up to correct wide open throttle. Propscan did the analysis for free and suggested a reduction in pitch along with a balance of pitch. Worked wonders for performance of vessel and paid fof itself in 2 seasons savings in gas irrespective of reduction/balance of load on engines.
 
You would be surprised at how p!ss poor some props come new out of the box. DAMHIK. My prop shop said it is not uncommon. In my case, properly tuned props more than paid for the tuning in a couple of seasons via fuel savings.
 
"There are more issues with misaligned or out of tune props that just shaking or RPMs. If you are wondering if your props need some tuning take them to a PropScan center along with the specs for your boat including current WOT, engine and trans specs. They will put your props on the computer and tell you if tuning will achieve any performance improvements.... and the scan is free. My Carver didn't have any vibrations or other indicators until I installed a Floscan fuel monitor and saw that one engine was burning fuel at a rate much higher than the other. Propscan found one prop pitched more aggressively that the other and corrected it."

Well sai adn I agree with Mike completely.
And once you have the props, engines and hull sorted out the way you want it is a good idea to 'benchark' that so you have good data for future comparison.
We use a simple list that shows temp, speed, rpm's, turbo boost, pyro temps, etc a a few common cruising rpm's for each engine. Also by taking a few simple digital photos of the dash we have a visual of what we should expect in a couple of weeks, months or years when our memories fail (or in my case minutes).
That way when you are concerned about the hull, a prop strike, or anything else affecting performance you have a simple place to go back to and see what if anything may be amiss.

Hope this helps
 
I was clueless as to what went into making and choosing a prop. The following book was recommended to me by RO's here.

=============================
The Propeller Handbook: The Complete Reference for Choosing, Installing, and Understanding Boat Propellers by Dave Gerr.

=============================

It gives all the info necessary to provide a prop shop for the best results. I provided it to mine and was very pleased.

I don't know if the prop shop owner used my info, the book, or developed the following on his own. It doesn't really matter. I don't recall this information sheet being on his site when I had my props done.

I have no affiliation with this company other than being a satisfied customer.

http://www.wildcatprops.com/zf-sizing.html

HTH
 
I was talking to a guy from Airmarine by Midway airport about my boat and me wanting to buy a cheap set of get-home props.

He suggested I tune my engines, go out and run the boat at cruise and wot, and record tach readings and mph.

They have a program they plug it all into after researching the boat, and then determine if the props are correct to begin with (he did say Carver did a pretty good job, but you never know). They would scan the props for free. I could then fix the props to the correct pitch.

But then he suggested that I do all the above, but use the original props for my get-home props, since Michigan now has a new type of prop, a DQX that is designed to get me further at rpm. They can show me what my fuel savings would be by installing the DQX. He claims they pay for themselves over prop-scan and adjusting.

How much is true, who knows?
 
Alignments and propulsion issues can be costly so, as long as there is no bad vibration or even noticeable vibration it is blissful to lay back and enjoy. Sometimes you're lucky, sometimes you're not. I worked with a friend in that business for years and I can't tell you how bad many of the OEM installations were. Some major boat brands (won't mention names) had chronic issues. I have relocated struts and shaft logs and sometimes even add pillow blocks with bearings. There was even a new 63 footer that needed an engine adjustment (and many other things). The adjustment slots on the mounts were maxed in opposite directions, they needed to be taken off and completely re-machined.

Mikee, Mike, and Smitty's advice is best place to start. PropScan and laser were barely off the drawing board when I was doing this. By the way, ignoring these issues may eventually damage other major components (transmissions). When you insert a straight shaft in near perfect alignment, it should slide out through the struts under its own weight (prior to connecting it of course).

"You would be surprised at how p!ss poor some props come new out of the box."

That was and probably still is true. We never installed a prop right out of the box.
 
I would highly recommend you purchase the book I mentioned. How big are your current props? Are they the right size? Is there proper clearance to avoid vibration caused by the prop being too close to the hull if you go to the DQX? The DQX minimum size is 17 inches.

The more you know going into the operation, the happier you will be with the results.
 
You haven't mentioned whether apparent boat & engine performance has declined for any reason since new and whether the upper 1/2 of the mfgr's WOT RPM range spec is readily attainable.

As it's been widely reported that some props may be out of marked specs right out of the box, it makes sense to get the props scanned by a PropScan shop for free with no obligation to service them so you would know for sure with a (also free) printed graphical and comparative data sheet for your boat records just how close they presently are to what you assumed they were(claimed specs), to the generally-accepted affordable "ISO 1" spec., and will reveal if they are presently a MATCHED set for minimum vibration & so one engine isn't unnecessarily constantly shouldering a bit more of the loads the other one loafs that bit.

And your records would then have a document showing your benchmark for comparison to condition revealed by future scans. The scan shop would also keep a computer file copy of the scans ,so if one happened to destroy a prop on a rock a new prop could be ordered over the phone that would be tuned to perfectly match the original (if single) or set-match remaining prop (if twins). No need to take other part of the set in to get matched.

Personally, I enjoy taking my I/B props over to RI to get them prop-scanned each year as I watch and discuss the clear results with the very friendly & helpful prop service master there. That way if I notice any discrepency in boat performance, I have a much better way of weighing the props likely influence on that. If you can be there to watch the scan & discuss , I highly recommend that over sending them .

I always keep in mind that it is unlikely ( certainly in this area )that boats that are well used each year will have their props escape some running contact with flotsam or ubiquitous pot buoys , etc. and noticed or not that just may have affected the prop specs with no obvious visual clues.

I'd also note that , as opposed to the Prop-Scan shops, the MRI scan system prop shop I once took my props to charged a hefty fee upfront for just the pre-scan so I don't go there any more.

I appreciated having this scan info and applying it to my benefit, but many people rarely have the scans or service done unless they have a bad grounding or other impact that more obviously requires service. Personal preference.
 
Sandy brings up very good points. I'll add to them that the element (water) itself is going to cause wear and tear. In my case, not enough to warrant annual tuning, but every three years at the most.
 
Thanks for all the thought and feedback. Some of the info needed to do the job right would have to be obtained and logged once she is back in the water. I will probably have to wait until Spring 2014 and get the performance info this summer. Unless of course there is some obvious issue that arises or strikes the props. Let's hope not!
 
You must log in or register to reply here.
Back
Top