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Worn Prop Shaft

10K views 23 replies 8 participants last post by  rhsanborn 
#1 ·
I figured I'd post a photo of my prop shaft as a warning to others. It looks like checking the packing box wasn't a priority for the first 30-ish years of this boats life, or maybe my expectations were too high. Regardless, this is the area where there packing rubbed on the prop shaft. I'll be checking for drips each weekend to make sure I get adequate cooling in the future. The first machine shop I spoke with wanted 200 dollars to repair this, and some lesser wear around the cutlass bearing. I'll be replacing this with a new prop shaft.
 

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#4 ·
Make sure the shaft you get is a "name" brand--I believe there are some out there in the shaft world. If I can believe the guys you replaced mine the second time in two years because it was wobbling, the first one was wobbling because it was not good stainless and could not be made straight by the machine shop. Guess there's some cheap junk out there.
 
#7 ·
I got a quote from Deep Blue Yacht Supply (Propeller Shafts for sale. Buy your Prop Shaft online and save.) and General Propeller (General Propeller Company). My shaft is 7/8 in diameter by 30 3/4 in length. AQ 19 is 150ish and AQ 22 is Just under 200 from either company. They both say AQ 19 is well within specs for my application. The strength difference between 19 and 22 is 50k PSI and 55k PSI per Western Branch Metals (Western Branch Metals: Marine Propeller Shafting). My coupling seems to be in very good condition. No rust, pitting, etc. It looks nearly new. I'm going to send it to whomever I buy the shaft from and have them take a look at it and make a recommendation. I chose the first two companies mostly because their order process is so easy. Henry Smith is here in Michigan, but their website is horrible, and they're a bit far for me to drive.

I'm open to tales of caution on my assumptions though. Most of my assumptions with regards to boats and sailing have been wrong :p
 
#8 ·
I will make some comments on the last "mail order shaft" one of my customers had to deal with. As shipped it was simply uninstallable.

Suffice it to say that by the time he was done with the local shop fixing the "issues" from the mail order company he was over $150.00 more than what the local shop would have charged to begin with and still had a shaft that was not AQ22, which is more corrosion resistant......

This is what he got:

Non AQ22 shaft (for salt water use AQ22 is more corrosion resistant)
SS key for the prop end (should be a brass key NOT stainless)
Sloppy key fit for the coupling end
Coupling simply slid over the shaft and was unsafe to install
Coupling set screws were not "spotted" into the shaft
None of the keyways were spooned
Coupling was never faced but didn't fit any way so it really did not matter
Shaft was .008" out of true which is well beyond the allowance for ABYC standards
No prop nuts
 
#9 ·
You're killing me MaineSail :p I'll call Henry Smith, but I'm giving them a hard time about the tripe they call a website. I'll let you all know how it turns out. I took a look at Western Branch Metals and couldn't even figure out how to order a prop shaft from them ... General Prop did ask me to send them my coupler to make sure it married up well with the shaft. They're based out of Bradenton, FL, but I'm not directly familiar with their operation.
 
#10 ·
We just replaced the prop shaft on Abracadabra. We had our yard do it. There's a lot of things on the boat I'm not afraid to tackle, but, especially being as this required dropping the rudder, this was not one of them. We don't have the final bill yet, but they quoted about $1000 to:
  • Drop the rudder (boat had to be in the slings for that)
  • Remove prop, old prop shaft, flange and cutlass bearing
  • Have new prop shaft made, plus repair/replace/recondition coupling flange, as-needed
  • Install new cutlass bearing
  • Install new prop shaft
  • Install new zinc
  • Reinstall prop
  • Align engine with prop shaft
  • Re-install rudder
  • Splash and check alignment
  • Adjust reversing gear ("transmission" for you non-A4 sailors ;).)
  • Test
Boat now does over 7 kts on the iron genny, even with some wind on her nose, with the ol' A4 sounding happy as a clam and running at lower RPM than it used to to get us to 6 kts :). It was worth it.

Old bronze prop shaft was bent, out-of-round, and exceedingly worn due to misalignment with the engine. Cutlass bearing was shot, too.

Jim
 
#11 ·
I just went through this. I ended up with a local shop that charged me about $490 to do my shaft and a couple other things.

The cotter pin broke off and then my brother tried to use a drill bit knock it out and broke that off in there.

It went like this;
me; What are you going to do with that?
Bro; this will get it out
me; dude, thats hardened steel Don't...
Bro; $#!+ it broke
me; okay put it down I'm taking it to a machine shop

Anyway, They got the pin out, removed and cleaned the prop, made the shaft with key ways and set screw dimples, replaced the prop, Faced the coupler, and made me a couple of 5/16 SS backing plates for some deck hardware.

I went through the same thing thinking about Blue water. Then, I figured by the time I got it with shipping and having a local shop add the dimples and face the coupler and add the key ways I'd have been at over $350 then the cotter pin/drill bit scenario another whatever that took. I think I probably paid a little more than I should have but, I think I used the wrong shop. In the end I've got a new SS prop that fits.

Go local, find a shop that does prop shafts, bring everything in, prop, coupler, key ways, set screws and let them fit it all out.

Just my $0.02
Danny
 
#12 ·
I also posted our progress in another thread. We're in the Great Lakes and are doing this before we put the boat in the water for the season. The rudder has enough room when in it's cradle to drop the rudder.

The rudder wasn't too bad once I folded my legs into positions not described or achieved by even the most accomplished yogi and squeeze myself into the rear locker. That was relatively easy.

The prop was a nightmare. The nuts came off fine, but I wasn't using the right tools. I was using a C-clamp with a split end, but it didn't have a place for a ratchet handle, so I couldn't get enough force. After 4 hours of trying all manner of things, I finally went and rented a prop puller from a local yard. It came off in about 30 seconds.

The prop shaft was really stuck in the coupler. We ended up attaching a piece of metal and banging on it with a hammer. It bent the end, but the prop shaft was toast anyway. That took a few hours.

The cutlass was long, slow, and tedious, and we stumbled on some oddities, but it did come out after cutting some wedges with a hack saw blade, and then putting a socket wrench socket with an extension down the tube and banging on it with a hammer for a bit. Our stern tube is made out of ceramic or something. I was expecting brass. As such, I had to be very careful when prying, as I'd damage the stern tube.

Now I'm trying to order all the parts. I'll be replacing the cutlass, which started this whole thing, the prop shaft, possibly the coupler, depending on what the shaft company thinks of it, at least the rubber tube that holds the packing nut, and maybe the whole packing assembly.

I guess I have never seen a dry bilge to appreciate it, but I just planned on continuing to use the regular old packing instead of the pricier PSS. We've been able to do all of this ourselves with some help from other sailors, so our total out of pocket cost will be:

New prop shaft: $200
New cutlass: $50
Prop puller rental: $25 (Nice guy)
Short length of rubber tube: $15?
New packing: $25?

TOTAL: $315

It was frustrating, but we learned a lot about the boat, and got to take a peak at things we should be doing each season for maintenance (checking the packing to make sure this shaft doesn't get damaged).
 
#14 ·
I also used a (somewhat) local prop shop and was quite happy I did. They fit and faced our old flange, provided new keyways, bolts for securing prop etc.

Here is one place to get the Buck Algonquin hose: Hose For Packing Box 1 1/2""I.D. For 3/4"" Shaft

MaineSail recommends the Gore GFO packing but you may find GTU (knock off) easier to find.

Good luck.
 
#15 ·
I'm going to take them the old cutlass, the old stuffing box, the original prop, the coupler, and the prop. I want them to make sure everything fits together well. I heard others say they may even repack the packing nut, and I'd just need to take it apart for installation, which would be great, although it shouldn't be that hard with everything apart anyway. I will make sure I get the buck algonquin kit, and I'll be looking to see if it might be worth putting in something like the PSS if I'm going to replace it all anyway.
 
#16 ·
The PSS system has its share of devotees and happy customers. Apparently the PSS for a 3/4" shaft is about $205: PSS Dripless Shaft Seal (Measured in Inches)

Maybe because I'm a cheapskate or maybe I'm happy to spend the $20 or so for new packing every 5 - 10 years that I can't really justify installing the PSS system. With the old fashioned stuffing box you will gradually note the drip rate increase as the packing wears down and the nuts may need to be re-tightened (very gradual failure mode).
You don't have to worry about tightening down any bolts with the PSS system but if it fails for whatever reason it is likely to be catastrophic (sudden failure mode).
Your boat, your money, your choices.
 
#17 ·
Apparently the manufacturer recommends you replace the rubber baffle every 7-9 years on the PSS, so it doesn't seem any easier for maintenance. I think I'll stick with the cheap packing and clean out the bilge every once in a while :p
 
#18 ·
Yes, if the rubber baffle fails (chafes, rips or whatever) you need plenty of duct tape or plenty of luck or both.

I like that the traditional stuffing box gradually lets you know that it needs tending to by starting to drip more then usual. It is a pretty robust and time tested design.

If you haven't already seen it here is MaineSail's authoritative tutorial on re-packing a traditional stuffing box: Re-Packing A Traditional Stuffing Box Photo Gallery by Compass Marine at pbase.com
 
#19 · (Edited)
TO the OP

I hope you don't mind using your situation to ask my question rather than starting a new thread.

It appears the the OP's shaft has some serious wear and is in need of replacement. With that said, could he not just lengthen the stern tube hose, polish up the shaft and re-pack the stuffing box? All else being equal, the shaft is straight, no miss alignment etc how much wear is too much wear?
Let's assume that the shaft is 7/8's or 0.875 of an inch and he has 0.050 of an inch wear, he has 5% wear. I find it hard to accept that the shaft is not up to the task of carrying the loads with 5 percent lose in over all dia.

Again I not suggesting he do the above just trying to understand why he shouldn't.

John
 
#20 ·
No worries Johnny, I'm curious myself, now that you ask. I think we'll wait for MaineSail to chime in. My gut says that you'd need to compress the packing more to get a good seal. I suspect it's more than up to the load, and the question would be maintaining a proper seal.
 
#21 ·
Actually, you can cut the Buck Algonquin tube down, not much, but enough to change the area where the shaft floats in the stuffing box. Or, you might be able to get a longer hose then the one I linked to which is only about 6" long, IIRC.
I had wear on my shaft where the cutless bearing is so there was no moving the point of contact but you can move the point of contact with a stuffing box by using a different length shaft log hose.
 
#23 · (Edited)
Here is my new stuffing box...



Here is the before shot...



Remember, only tighten it up hand tight until you launch. You can go tighter but you can not back off. Apparently the process is to run for a bit and check and tighten several times until you get it to drip the way you want it. Over-tightening is bad. could cause the thing to over heat if it isn't dripping.
 
#24 ·
I finally have all the pieces. I'll be putting it all together this weekend. I got a new prop shaft from Henry Smith here in Algonac, Michigan. It's fantastic quality. I'll take the recommendation above and only hand tighten the packing nut until I run it for a few hours. Then I'll set the packing tightness, and re-align the coupling.

Thank you everyone for your comments/advice.
 
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