Prop Shaft - where to start and end....

[bradh]

At end of season haul out, my prop shaft looked bent. I could see what looked to be run out between the shaft and the hull (where it enters at the water) when I hand turned it.

When I removed the shaft, I noticed about 5-10 degrees of slop/backlash at the coupling and shaft (Is that normal or excessive?). The key way on the coupling looks to be distorted (wider aft). Also the detent on the shaft for the coupler set screw looks a little beat up (see picture). When I put the shaft on a granite surface plate, I only get about a 0.010 in of bend (is that excessive?). I am wondering if the shaft is not really bent all that bad and the run out I observed was just due to slop in the key way (probably caused over time by misalignment)?

So I am trying to decide how carried away to get here....
1) new coupling, cutlass
2) new shaft, coupling, cutlass
3) new bigger 7/8 shaft, coupling, stuffing box, cutlass, reprop with an Indigo

I currently have a 3/4" shaft, with a Michigan Saiiler 2 blade 12-7. Option 3 comes down to how great is an Indigo on a 35-II and how much does it add drag under sail?

I have also gotten mixed responses on the 3/4" shaft diameter. I have seen specific reviews of my boat (Ericson 35-II) that say the shaft is undersized. But others tell me that it is appropriate (46" long shaft).

Thanks in advance for thoughts and feedback.


Brad

[Dave Neptune]

Brad, looks like the coupling was a bit loose for a while, thus the tiny bit of distortion and the wear on the set screw detent. Neither look to be bad enough to worry about.

RE the .010 runout that isn't to bad depending on where it is along the shaft. That little amount can easily be "peen straightened" if it does cause a wobble.

Did you have any vibration to speak of?

Dave Neptune

[bradh]

Dave,

No unusual vibration. Though we purchased the boat mid-season, so I am just getting to know her usual "feel".

The bend seems to be right about mid shaft. So I think I will look at getting it peen straightened, swap out the cutlass bearing, and get a new coupler. Does that sound reasonable?

Thanks for the feedback!

Brad

[Dave Neptune]

Brad, sounds good. I would also be sure it was the correct keyway in the coupling.
Pull the coupling and have whoever is doing the straightening check it. May be fine once cleaned up and tightened properly. If you replace consider a split coupling as they clamp for additional holding.

I too have the E35MkII with a 3/4" shaft, no problems for the 35 years I have owned her. Did replace the packing and straightened the shaft. I do peen straightening all the time!!! When you take the shaft in mark where the cutlass and the packing are so no peening will be done in those areas.

When replacing BE SURE TO MOUNT A RETAINING COLLAR on the shaft just incase!!!!!!!

Dave Neptune

[bradh]

Dave,

Sure enough - the key is a nice slip fit on the shaft, but the key way on the coupling is larger (taking measurements tomorrow). Any idea what the width of the coupling key way is supposed to be? I'm just wondering if I get a new coupling, it will be the same size and it's the shaft that is actually wrong (undersized).

Thanks!

Brad

[bradh]

The shaft key slot is 3/16 and the coupling is 5/16. (I see on Moyer's website that the standard is 3/16 on the coupling). So that explains the backlash. I am also assuming that allowed the set screw to slide around in the detent on the shaft and caused what looked to be bent shaft run out. So I am going to get the shaft starightened, new coupling and key.

On your suggestion for the shaft collar. Is it bad form to rely on the zinc? The zinc is between the hull and the strut.

Brad

[ndutton]

You may want to compare the cost of a new shaft vs. repair of the old one. For a small additional investment you could benefit by having no wear to deal with at the stuffing box and strut.

[bradh]

Dave,

So it ends up the key way in my coupling was over-sized. (1/4" key on shaft and 5/16" on coupling). So I would have to enlarge the key-way on the shaft.

How much of a difference did putting an Indigo on your E35 MkII make? Is it work the $? This is my second season with the boat. First season just made me expect to watch the bow swing left when backing out of the slip. So I know what to expect now, but still not proficient in correcting for it.

I came up with 3 options (ala Neil's suggestion):

Option 1 - New 3/4 Shaft ~$470 (2 Piece coupling, Cutlass Bearing, shaft, anode)

Option 2 - New 7/8 Shaft - $900 (Indigo Prop, 2 piece Coupling, Cutlass Bearing, Shaft, Stuffing Box, Prop Nuts, anode)

Option 3 - Rework current 3/4 Shaft - $400 (2 piece coupling, cutlass bearing)


I think option 3 is out. So the question becomes if I go to a bigger shaft and get an Indigo.

Brad

[jbsoukup]

for a bigger shaft, would you not also need a new strut? ( in addition to cutless, stuffing box, coupler)

[romantic comedy]

I would stay with a 3/4 shaft. It has worked and other boats have them successfully. No need to spin more then you have to.

The indigo prop is available for 3/4.

[sastanley]

I agree with the others. $500 is about what I spent to replace my shaft, coupler, cutless bearing, rear main seal (while I was that deep into it.) I also did an Indigo prop (not included in that $500), which started the whole thing, and took me down the rabbit hole of the shaft replacement. This also allows a nice fresh 'fit & face' with new parts, and you should be able to align everything relatively easily and it will be like a new motor with the smoothness and alignment!

I like option #1. If Dave Neptune's been spinning a 3/4" shaft across the Pacific Ocean this long without problems, I think you'll be OK!!

[bradh]

I don't have to replace the strut because I can fit a cutlass bearing for either a 3/4" or a 7/8". I also have room in the log (for up to a 1"); if I had to replace the strut, it would be a slam dunk to stay at a 3/4". I have the Michigan 12x7 two blade that loves to walk the boat to port. So based on your feedback, this all comes down to if I should change to the Indigo (and if I should, I might as well, go 7/8", right)? It sounds like a new shaft is the way to go, but do I put a new indigo on it while I am there?

[ndutton]

Before committing to the Indigo, I suggest 'going deep' with questions for Dave Neptune and Shawn Stanley. They both have Indigo's and while Dave's boat is identical to yours, Shawn's is very close in LWL and displacement.

Tailor your questions to how you use your engine. Engine use in and out of the slip is very different from motoring for days on end. How much stopping power do you need? If you're in a crowded area, emergency stopping power may be an important feature. If you have a downwind slip in a typically windy marina, same thing. Racers would be apoplectic over a three bladed prop unless it enhanced their handicap rating greater than the sailing performance hit.

edit: BTW Brad, next time you're backing give her a burst of thrust to just get her moving then immediately shift to neutral and coast backwards. You'll have much more control.

[BadaBing]

Its hard to argue with the benefits of.the indigo, if your running direct drive.

[romantic comedy]

Brad, I have the Indigo on a Tartan 34. It backs to port big time. It is almost impossible to back down on the anchor.

Once I get some way on, it goes fine backwards. Docking can be quite the challenge if I need reverse. I come in at a snails pace since backing to port screws me up.

I still would recommend the Indigo though.