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cap'n chronic
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Discussion Starter #1
How does one go about removing a martec folding prop from the shaft?
im planning to send it out for a rebuild but I am wondering if the shaft itself should get any attention.
The old martec had excessive play (especially where the baldes pivot)to the point of a nasty vibration thru the boat when under load.
on a side note the cutlass bearing was replaced last spring and the prop strut was torqued down and sealed.
Other than this prop being old and wearing this way i have never had anything stuck in the prop or hit anything with it and neither has the previous owner, my father.
Is there any chance the prop shaft may have warped due to the play in the prop blades?
Acording to the build sheets for my boat the prop im removing is the one fitted to the boat from the factory.
Btw, boat is a c&c 33 mk1.
Thanks.
 

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I replaced my cutless bearing this spring. I tried a half dozen pullers, broke three and still couldn't get the prop off...heat...pbblaster...etc...all tried to no avail. Luckily it was a two blade and I cheated it out past my rudder with no room to spare. I took everything to a marine machine shop which straightened the shaft and balanced the shaft and prop as a rotating assembly. Given the cost, it probably would have been cheaper to go with a new shaft, but even though the prop looked good, who knows? What I do know is that the job is a PITA and it is worth spending the time and money to do it right the first time.

Regarding your Martec. I strongly suggest you contact them directly on proper removal. I checked their site, but there is precious little detail on it regarding removal and the installation instructions don't make sense to me as I don't have the prop in front of me.
 

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How does one go about removing a martec folding prop from the shaft?
1.- Remove the two cotter pins securing the pivot pin
2.- Slowly drive the pivot pin out from the "ears", making sure not to drop the blades as they come free
3.- Remove the two cotter pins securing the barrel nut
4.- Using a 4" long, 1/2"-drive socket extension, back the barrel nut off an inch or so, but do not remove
5.- Leaving the socket extension in place, fit a prop puller to the body of the prop. The socket extension will act as an extension of the shaft and the prop puller should be fitted over it.
6.- Once the body of the prop is loosened, remove the barrel nut
7.- Remove the body of the prop
 

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depending on access where you can view the shaft inside the boat, you can tell if the shaft is warped.

tie the boat up and put it in gear. go look at the shaft. wear no loose clothing, not even long sleeves, keep your hair up. get a flashlight and take a pencil and bring it up to touch the shaft. do this at one point on the shaft, then do it at another spot at a right angle to the first spot. move up and down the shaft. the pencil point should ride smoothly around without high or low spots. do this in a few places up and down the shaft. if the shaft is off kilter, you will notice it making you hand move.

another variation, which has to be done more carefully ( because the calipers can bind on the shaft), is to slide preset calipers halfway over the shaft. move the calipers up and down, back and forth. if the calipers should move side to side as the shaft spins, it's out of whack. you will know it.

this checks the shaft inside the boat. 90% of the time that is where the shaft has warped. of course, the few inches of shaft outside the bearing may be what is bent, but probably not.

good luck
 

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1.- Remove the two cotter pins securing the pivot pin
2.- Slowly drive the pivot pin out from the "ears", making sure not to drop the blades as they come free
3.- Remove the two cotter pins securing the barrel nut
4.- Using a 4" long, 1/2"-drive socket extension, back the barrel nut off an inch or so, but do not remove
5.- Leaving the socket extension in place, fit a prop puller to the body of the prop. The socket extension will act as an extension of the shaft and the prop puller should be fitted over it.
6.- Once the body of the prop is loosened, remove the barrel nut
7.- Remove the body of the prop

To this excellent post I would add..

If the puller "loads up" without any apparent release of the prop on the taper, use a moderate sized ball peen hammer to give the end of the tensioned puller a sharp rap. This will often "pop" the prop down the taper of the shaft. The loosened-but-left-on barrel nut will prevent the assembly from flying off the shaft at that point, though be prepared to catch the puller as it is released.
 

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I prefer Fast Bottoms use of a prop puller, as it's less likely to do damage, but I thought I would post Martec's guide from their website:

HOW TO DISASSEMBLE AND RETURN A FOLDING PROPELLER FOR RECONDITIONING



Reconditioning of your folding propeller will correct functioning problems with the unit—including opening and closing, and vibration.

Please note: that if after refurbishing the propeller you still experience functioning problems, these maybe related to wear and maintainance issues in some models of transmissions.

This service is necessary approx. every 5 to 10 years depending on, the enviroment that the prop lives in, amount/type of use, size of prop, and number of different operators.



DISASSEMBLY OF FOLDING PROPELLER

APPLIES TO


MARK II EXPLORER
MARK III ELIPTEC close blades together
remove the two cotter pins which hold the pivot pin in place to the hub (connecting blades to the hub).
Tap-out pivot pin & remove blades
Remove two cotter pins; from opposite sides of hub and each one extending through the hub into the shaft nut. Pinch ends of cotter together & pull from outer side of hub.


Use (socket) extension to reach shaft nut (recessed inside end of hub), then, turn nut counter-clockwise to loosen.
Do not remove nut entirely, as sometimes the hub (next step) may come flying-off the shaft with a lot of force. For this same reason, do not stand directly aft of the shaft, but rather, stand to one side.

Note: 3/8” extension fits 3/4” & 7/8” shaft, ½” extension fits a 1” and larger shaft sizes.

If you do not feel totally comfortable or competent in performing any of the following steps, and/or you do not have the appropriate tools/equipment, you should consult &/or hire a professional (boatyard, prop shop, etc...) to perform this service

It is important that you understand a propeller hub and shaft are machined tapers, which generate a tremendous amount of holding power.

Start by tapping the forward end of hub with a hammer and punch in order to separate the hub and shaft. Use caution when using this method, as prolonged hammering can damage the hub and shaft.

Please note, If not successfull after a few tries with the hammer and punch method, it will then be necessary to use a wheel-puller.

If at this point you have not had success with the removal of the hub from the shaft, we suggest that you consult a professional.

Look for “key” (bronze) as hub is removed; you will need it when re-mounting the hub on shaft.


RECONDITIONING
SERVICE Please send the following parts to Martec:
(1) pair of propeller blades
(1) hub (big piece which slides over shaft & attaches to blades)
(1) pivot pin (possible to re-use)
Please keep the shaft nut and key unless they are damaged and need replacement. These are not needed during re-conditioning, but are important for the re-installation. Martec will return the refurbished propeller with a new set of cotter pins.

Please include a brief note in the box with the propeller giving us your name, address, telephone number, and returndate. Also be sure to insure your package.

Most propellers are scheduled on a two to four week turn-around. However, if the circumstances warrant a quicker turnaround, we will make every effort to meet your particular schedule/launch date.

You may pay for the service by VISA, M/C, AM. EXPRESS or check if time permits.

Average cost is approximately $210.00 - $250.00 US + Shipping and Handling. Please note that the propeller size & metal condition mayl affect the average cost.



We are always happy to send you an estimate on any reconditioning work you may need. E-mail address: [email protected]





MARTEC Eng. Corp
2257 W.Gaylord St.
Long Beach , CA 90813 USA

Tel: (562) 435-4494 · Fax: (562) 435-7846
 

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If the puller "loads up" without any apparent release of the prop on the taper, use a moderate sized ball peen hammer to give the end of the tensioned puller a sharp rap. This will often "pop" the prop down the taper of the shaft.
Tension+vibration+persistence. There is no prop that cannot be removed using these three tenets. I have removed very few props that didn't require some aggressive pounding to the puller with a hammer.

The loosened-but-left-on barrel nut will prevent the assembly from flying off the shaft at that point, though be prepared to catch the puller as it is released.
A short lanyard from the puller to the shaft will relieve the user from having to deal with the puller as the prop comes free.
 

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cap'n chronic
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Discussion Starter #10
thanks for all the helpfull info.now i just need to wait until the temperature gets back into the positive so i can attempt all this.
i have portable oxy/acet torches i could bring up with me to heat the corrosion out of it.
 

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Removed my prop last Spring as per the Martec instructions. Had it refurbed etc and all the problems (vibrations etc ) disappeared. Likely don't have to say it but be careful with the torch. Heat takes temper out of the metal. Tension, vibration etc are safer!
Don - shivering in Halifax
 

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thanks for all the helpfull info.now i just need to wait until the temperature gets back into the positive so i can attempt all this.
i have portable oxy/acet torches i could bring up with me to heat the corrosion out of it.
Blue wrench fixes all,
Just burn it off and buy a new one...:D

Mark
 

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Same prop, same boat, same vibration

I joined this forum to ask this question: Like you, I have an Express 30 (hull#3). I'm the original owner, and my Eliptec prop has vibrated since first launch. Given that history I'm not confident that refurbishing the prop will fix my situation. What was your experience with vibration, and is it still vibe-free? Did you send it to Martec?
/Andy, RunawayExpress

Removed my prop last Spring as per the Martec instructions. Had it refurbed etc and all the problems (vibrations etc ) disappeared. Likely don't have to say it but be careful with the torch. Heat takes temper out of the metal. Tension, vibration etc are safer!
Don - shivering in Halifax
 

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Andy. Sent the prop to Martec for the rebuild. Works much much better to the degree there is no vibration now. Previous vibration was enough to be intolerable at mid and higher rpm.
Don
 

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Different vibes?

Thanks Don, I wonder if my problem is different. The vibration is only in forward gear, and it starts at low rpm, gets noticeable at about 1200 rpm and you cannot responsibly take it past 1500 because of the pounding, UNLESS, amid the pounding you catch it just right in a fraction of an instant of balance, and once caught you crank it up to 2000+. Then all is fine. Until you slow down. Sometimes I can't catch that instant of balance for 5-10 minutes. I've always considered this to be a failure of the blades to open in balance. Again, does this sound like the prop or the shaft, and since it's been a problem since original delivery of the boat, is it worth $200+ at Martec only to find out it's the shaft? Or the installation?
Andy
 

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This doesn't really sound like a half-open prop. The vibrations from that situation feels like it's trying to rip out the strut at under 1000 rpm.

In case it is something similar (binding and only partially open on one side) have you tried spinning the prop up in reverse just before putting it into forward gear? Our old martec used to only half-open half the time... this technique prevented that most of the time.
 

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My estimates for the rpm when the bumping and then pounding develops might be high. And it's there every time I increase from idle. Reverse gear doesn't have this behaviour, although reverse is always a bit rougher than smooth forward, because the blades aren't as fully open, right? However, spinning in reverse doesn't seem to help, but thanks for the suggestion. When I return to forward as rapidly as I think I can safely, the thumping is there. Conceptually I would think you'd have to actually move the boat in reverese to keep the blades open and then fling it into forward. Dramatic. So the only technique that works, albeit poorly and uncertainly, is to take it to an rpm in forward where the bumping is audible and listen closely for that half second of non-bumping when you can yank the rpm up. Once you're through and clear, all is fine.
 

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Andy. I had used the reverse to fwd occasionally and had limited success. The Martec prop may have several issues. One is the common not opening in balance but the other is worn or bent pins which will cause a blade to wobble. I suggest you send an e-mail to Martec, describe the situation fully and see what they say in response.
Don
 
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