need new prop shaft and coupling

SPembleton · May 31, 2016, 12:38:29 PM

Last week i lost reverse and finally got someone out today to look at my boat. The key came out of the coupling and the entire prop shaft pulled out about 0.5 in from the coupling. The set screws scored the end of the shaft. The mechanic said i need a new shaft and coupling. I dont like spending money, but i really don't like spending money on cheap stuff that will just break again. Therefore, after reading a lot of posts on this site, i think i am going to get a vetus coupling. The yard will have the prop shaft fabricated locally.

My question is where is the best source of the coupling. Neither Defender or Hamilton seem to have them. Do i have to go through one of the "authorized dealers" from their website? Does anyone have a good source that is both inexpensive and fast (yes, i know those don't usually go together!).

Noah · May 31, 2016, 01:19:03 PM

Better check to make sure Vetus (Bullflex, I assume?) will fit with your PPS dripless system. I have heard there may be some issues. I bought my Bullflex from one of local Los Angeles-area Vetus dealers (NEWPORT HARBOR SHPYRD) and they had to order it. $530(+/-) incld. shipping.

SPembleton · May 31, 2016, 01:55:52 PM

Thanks. I will confirm that with Vetus tomorrow.

Ron Hill · May 31, 2016, 02:31:26 PM

Steve : If the keyway is still OK and the key will still function in the coupling - here's what I'd try before I invested in a flexible coupling.

Back out and remove both set screws. Engage the shaft and key back into the coupling. Take a 1/16" drill bit and drill into the shaft to a depth of 1/32" . Make sure the set screws still have a point. Reinsert and tighten the set screws and reinsert new lacing wire after they are tight.

All that you've done is to give the setscrews something to "bite into" and hold the shaft in place when going into reverse. Now you can spend your Boat Bucks on something else!!

If you still want a flexible coupling you might also look at PSS!!

A few thoughts

Ed Shankle · May 31, 2016, 05:55:25 PM

I ordered my Bullflex directly from Vetus. But that was many moons ago, so I don't know if they still accept direct orders. Worth a try though.

Ed

SPembleton · May 31, 2016, 05:56:04 PM

Thanks Ron. I will ask the mechanic about that option. When i asked about just installing a coupling and keeping the shaft, he felt that the keyway had been ground down so much at the end that there was not much of a slot left, and tightening the set screws around a thinner shaft would shift the alignment of the shaft. Evidently the set screws ground down the end of the shaft and most of the keyway. It is amazing how fast that happened. Less than a minute of running in reverse.

I will also look into the PSS flexible coupling, but i have not seen much mention of it. Has anyone else used it?

lazybone · May 31, 2016, 06:24:29 PM

Quote from: SPembleton on May 31, 2016, 05:56:04 PM
Thanks Ron. I will ask the mechanic about that option. When i asked about just installing a coupling and keeping the shaft, he felt that the keyway had been ground down so much at the end that there was not much of a slot left, and tightening the set screws around a thinner shaft would shift the alignment of the shaft. Evidently the set screws ground down the end of the shaft and most of the keyway. It is amazing how fast that happened. Less than a minute of running in reverse.

I will also look into the PSS flexible coupling, but i have not seen much mention of it. Has anyone else used it?

Any machinist can easily increase the diameter of your shaft by Knurling and then re-machining to the proper fit.

SPembleton · June 01, 2016, 03:11:08 AM

I am starting to total the cost of things up, and it is getting bigger than i was thinking. I only use the boat for daysailing and only use the engine to motor to Lake Michigan about 1/4 mile. Is there any issue with using the factory coupling? I realize that i may get a little more vibration, but I have been living with that for as long as i have had the boat. Can i just buy the coupler from CD and buy the shaft locally. Probably also replace my cutlass bearing also.

mainesail · June 01, 2016, 04:19:16 AM

Quote from: SPembleton on May 31, 2016, 12:38:29 PM
Last week i lost reverse and finally got someone out today to look at my boat. The key came out of the coupling and the entire prop shaft pulled out about 0.5 in from the coupling. The set screws scored the end of the shaft. The mechanic said i need a new shaft and coupling. I dont like spending money, but i really don't like spending money on cheap stuff that will just break again. Therefore, after reading a lot of posts on this site, i think i am going to get a vetus coupling. The yard will have the prop shaft fabricated locally.

My question is where is the best source of the coupling. Neither Defender or Hamilton seem to have them. Do i have to go through one of the "authorized dealers" from their website? Does anyone have a good source that is both inexpensive and fast (yes, i know those don't usually go together!).

A properly fit straight coupling is not "cheap stuff that will just break again" but it is all in the fitting of the coupling and shaft as to how it will work. There are a LOT of bad shafting shops out there who have NO CLUE.

My guess is that your coupling had been, at one time, removed from the shaft & the yard or DIY re-used it, a very bad idea. Once a shaft is removed from a coupling the "interference fit" is almost always lost and a new coupling and a new "fit & face" is required. Once the "fit" is gone it is only a matter of time before a failure occurs. I have been warning of this extremely poor practice (re-using a coupling) for well over 20 years yet yards and DIY's still do it.

Beyond that your shaft was one of the ones from a bad AKA Hack Shop shafting shop. How can I make such an assumption? Because the set screws on the coupling are supposed to fit into "spots" in the shaft or dimples made by a drill. Even if the key fails it would be extremely rare for a spotted shaft/coupling to actually back out, this is what spotting is for.. I have seen them come loose but never seen one back out unless the shaft was not properly "spotted"...

FWIW I had to go back and find the image but this guy actually read my PSS article and admitted he chose to ignore my advice about replacing the coupling.

"RC,

I felt the need to drop you this note whilst I swallow my pride. The attached picture is the result of not listening to your advice. The ordeal cost me $4672.00. Had I completed the job properly, as I was clearly instructed to do, it would have cost an additional $124.00. Feel free to use this picture on your site so other readers do not repeat the mistake I made."

His boat suffered serious water damage which destroyed the cabin sole. He also required a tow and replacement coupling & shaft not just the coupling.

Roc · June 01, 2016, 05:09:01 AM

I have a dripless seal and the flexible coupling that fits in the area is the Federal Flexible coupling. Was discussed before in these posts.
http://c34.org/bbs/index.php?topic=5213.0

The Vetus might be too long to fit between the seal and the gearbox. Not much room on the MkII. A flexible coupling is worth the effort. One of the best improvements made.

Stu Jackson · June 01, 2016, 10:13:30 AM

Further to Maine Sail's post in reply #8, this is his article on new shafts and couplings from his website. We have been recommending for years that skippers bookmark his website in addition to the information on our C34 site.

http://www.pbase.com/mainecruising/new_shaft

SPembleton · June 01, 2016, 10:53:23 AM

Thanks for all the great info, as usual!

I spoke to Vetus and Federal Marine this morning. The Vetus rep used to own a Catalina dealership and said he doubted his product would fit with the drippless and it was almost $600. The Federal product was only about $300 and the rep assures me that it would fit. Since many have posted that they like the Federal, I have asked the yard to get that one. they also like dealing with a local shaft manufacturee and will 100% warranty his work, so I will probably go with him also.

Now I just have to wait my turn to get.the work done.

Thanks all!

Ron Hill · June 01, 2016, 01:47:20 PM

Steve : I assume that your boat is on the hard?

You should be able to save a few bucks on a new drive shaft as you will NOT need a keyway with either a Vetus or PSS flexible coupling.

A thought

SPembleton · June 01, 2016, 04:08:59 PM

Thanks ron. I am not yet on the hard, but hope to be soon. I think i will be using the Federal flexible coupling. It does require a key, but it is about $200 cheaper than the Vetus. Havent priced the PSS one.

SPembleton · June 21, 2016, 09:46:41 AM

As a followup, I am installing a Federal Marine flexible. Price was great and it fits better on my Mark 1 with a PSS dripless. Thanks to everyone for their advice and especially to ROC for the suggestion about Federal. I would not have know about them otherwise.

I asked the yard why this happened. They said that since my old shaft was bronze, I probably should have tightened the set screws on the old coupling every year to prevent it. I don't know what brand I had, but it does not appear to be OEM because there was a small white spacer in it that I don't think the OEM had.

Does anyone tighten their set screws? New coupling doesn't have set screws, but I was going to suggest to my slip neighbor that he check his.