E35-3 Prop Shaft Strut - a look inside - and a zinc question

[Prairie Schooner]

Also those set screws are NOT reusable. So before you put it back together you'll need to order replacements. Not sure how old your PSS is but if it's 6+ yo or more it may be time for that project too(while your in there). They sell rebuild kits with new bellows, clamps, o-rings, and set screws of course. I think I paid about $90-100 for the kit but that was a while ago...

Dave,
Are those just standard allen set screws? Normal, non-marring, points, ? I could just add them to the McMaster Carr order I've got started. Otherwise I'd have to pay for a PSS o-ring kit plus postage just to get some screws. I'm not going to take the coupler off the shaft or rebuild the PSS this go-round.
For that matter, why can't they be reused? Do the tips get too work hardened?
Thanks, Jeff

 

[Dave G.]

Are those just standard allen set screws? Normal, non-marring, points, ?

I cannot tell you the spec as I just don't know other than they are SS. I do know by many articles I have read and also the manufacturer's emphatic one use only they should not be reused. They are what locks the rotor onto the shaft which keeps compression on the bellows and the water out. You may be able to call PYI and they could give you the specs. They do sell a set screw kit....

Set Screw Kit

This Set Screw Kit comes with the necessary set screws and thread lock to install or adjust the stainless steel rotor of the PSS Shaft Seal. This kit includes six stainless steel cupped point set screws and thread lock.

store.pyiinc.com

 

[Prairie Schooner]

. . . You may be able to call PYI and they could give you the specs. They do sell a set screw kit....

Thanks Dave. I went ahead and ordered them. I just wrote them, though, to see if I can get an answer on why.

 

[Prairie Schooner]

. . . I just wrote them, though, to see if I can get an answer on why.

Well that was fast. This from the rep:
"The set screws provided with the PSS Shaft Seal are cup-point set screws, which compress onto the shaft when tightened. Any re-use of the set screws will not allow the cup point to lock onto the shaft properly."

 

[Prairie Schooner]

Status update. I think I’ve got a clear plan for reinstalling the strut. It’s somewhat different from what I’ve detailed above. I’ll present it at a later date. In preparation I put shims in the shaft log on the outside to center the shaft there. Then I connected the coupler back to the transmission shaft. The prop shaft is pretty significantly out of center on the inboard side of the log. I’m inferring from this that the engine will need to be skooched to port. It looks like the PO might have moved the engine mounts (3) to starboard at some point. Maybe to make room for the upgrade alternator? I think the sideways adjustment available in the mounts as they sit might not be enough. So, I’m doing other things and cogitating. It’s a little overwhelming to think about moving the mounts. Any input welcome. Thanks, Jeff

 

[bigd14]

It’s a little overwhelming to think about moving the mounts.

Dealing with the mounts is not too bad and you could address what I see to be an inherent flaw in the design of the engine mount system. The engine mounts are attached to the beds with lag bolts that go through fiberglass and softwood. Over time with adjustments and vibration these can lose their hold and the engine can no longer be held in place securely. There are many ways to address this but if you have to relocate the engine mounts now is the time to deal with it.

Now would also be a good time to actually replace the engine mounts. It looks like there is a spacer plate underneath them. I wonder why that is there? Did the engine mounts sag over time and that was the fix?

Lots of threads about this issue.

M25xp, convert from 3 point mount to 4?

While eyeballing Beta Marine engines at the Chicago Boat Show this weekend I mentioned to the rep my problems with trying to vanquish vibration at certain RPM with the M25xp on my E34. He claimed that the largest cause of vibration problems associated with this engine is due to the 3 point...

ericsonyachts.org

M-30 Sound right? + Motor mount issue

Hey gang, 2 things. I posted a short video of my M-30 running (TURN YOUR VOLUME DOWN) and wanted to get your thoughts on whether it sounds Ok or if there's something I should be concerned about. The belt seems awful loose but there's no indication of slippage and the alternator seems to be...

ericsonyachts.org

Engine Mount - Sheared Lag Bolt - Inside Stringer Photos

So this weekend I began the process of cleaning up my M25XP for painting. In the process I discover the forward/starboard engine mount has lag bolt that first appeared loose, and on further inspection is sheared off. It’s hard to get a good view, however the threads will not engage at all and...

ericsonyachts.org

 

[Loren Beach]

Now would also be a good time to actually replace the engine mounts. It looks like there is a spacer plate underneath them. I wonder why that is there? Did the engine mounts sag over time and that was the fix?

Worth noting is that over time EY would put some "stock" spacers under mounts on engines. All four of our mounts had spacers between the mount and the frp bed log molding.
That was changed/improved as a part of our re-power. New aluminum flat bar was fitted to each side to set the proper height. Those alum. bars were drill and tapped and machined, and finally Hard Coat Anodysed.
On our particular boat, the wood under the factory frp was determined to be oak. (FWIW).

O34 - Old engine out, planning for the new one

Since, for several reasons, this project needed to be done at the slip, I needed to lock the shaft in position. Totally. It was believed to be well-aligned, and it could not be allowed to move forward and relax the spring-bellows in the PSS seal...

ericsonyachts.org

Note that long tapered wedges were placed below each aluminum bar to achieve the correct *angle. Interestingly enough, EY had "solved" this problem by using shorter height spacers under the rear mounts compared to the front mounts.

*Not completely certain, but when interior tooling was designed/made with the incorporated bed logs for the O-34, the specified engine, at Pacific Boats, might have been a two cylinder Yanmar. EY was using all Universal engines, unless a customer was insisting on a Yanmar.

 

[Pete the Cat]

Well, as someone who struggled with these projects. I think your thinking is very good on this matter. Just as a matter of record, it is very common for builders and engine installers to put aluminum shims under the feet or to push the mounting up/down and sideways to make things align. At the boat yard where I worked, they generally have shims of various thickness available when doing a new engine replacement--never assume the hull is still the same shape as it left to mold years before. The boats and structures are never perfect out of the mold and I do not think there is much of a clue to be taken from what you are seeing about what was done previously. As far as the three point engine mounts; I have never seen any real testing of the theory that engine four mounts is better than three in a triangle--when the one longitudinal mount is right there where the fore and aft force is mostly pushing up and down (not laterally with the four mount arrangement--which appeals to my rudimentary understanding of physics and structural engineering) and aligning the engine properly is made considerably easier. If you have ever done it--getting the four mounts reliably in the exact same plane is a bitch--and on many boats is just about impossible to do with any real assurance on many boats due to access issues. I listen to all the folks who offer advice, but with caution and reflection (that should include me). As mentioned before, being able to set the strut position is a rare opportunity to get the whole drive system perfectly aligned. I think the TAFG is a great idea for keeping things set once it is done right. Other boats can move and mounts can loosen. I no longer deliver boats, but I recall that most boats we moved needed attention to alignment.. It is one of those most overlooked maintenance items after cooling system maintenance. Folks would rather spend the time and money on electronics or shiny stuff that shows. The stuff you are doing is important and you are taking the right amount of time to save problems in the future. Good luck.

 

[Prairie Schooner]

@bigd14 @Loren Beach @Pete the Cat Thanks gentlemen.
So, I think for now I'll proceed with installing the strut, making sure it aligns the shaft perfectly in the log. Meanwhile I'll research engine mounting and let the tail wag the dog.

 

[bigd14]

I think the TAFG is a great idea for keeping things set once it is done right

When I replaced the strut and engine mounts I rough-aligned the motor by feel- e.g. when the prop turned easily I tightened things down. The sweet spot of alignment to get the prop turning smoothly was very small. I figured I would “do it right” after a month or so once the boat was splashed as I heard that the boat would flex and throw off any alignment. But I never actually did since I can turn the shaft with my pinky finger on the coupler and it has remained smooth as silk like this for the past 4 years. Maybe that is not a good measure of alignment but it sure seems to work well.

 

[bigd14]

As far as the three point engine mounts; I have never seen any real testing of the theory that engine four mounts is better than three in a triangle-

I went with four but if doing it again I would stick with three, for all the reasons you mentioned.

 

[bigd14]

"The set screws provided with the PSS Shaft Seal are cup-point set screws, which compress onto the shaft when tightened. Any re-use of the set screws will not allow the cup point to lock onto the shaft properly."

Maine Sail recommends the addition of a shaft collar as backup to hold the bellows in position if the setscrews fail. Cheap insurance. There was just enough room for the PSS and the collar on my 30+, hopefully you have a bit more room on your boat.

Installing a PSS Shaft Seal - Marine How To

Originally Published March 9, 2004 Disconnect the Coupling From the Transmission Day One: 1- Loosen the packing gland nut. 2- Loosen and remove the four nuts between the transmission and coupling. 3- Push the shaft towards the stern separating it from the transmission. 4- Apply a...

marinehowto.com

 

[Prairie Schooner]

Well, after a bunch of hemming, hawing, asking, listening, pondering, and procrastinating, I think I'm ready to glue this up. One inch ID pvc pipe made a good spacer inside and out of the shaft log. I split it in three laterally. Modified pvc T-fitting, screwed to pop-it to hold things in place. The initial install will be done with Pro-Set ADV-176/276 for G10 to bronze, then that assembly into the cavity. Then glass it all in, normal like.

 

[Pete the Cat]

Very smart. An improvement on the way I did it with wedges and clamps. You will be happy you took the time to make this right. I actually think that the factory did something like this in the original construction process. You might consider drilling a hole in that strut and putting a disk zinc in it. One of the problems when folk repower with a different engine is getting the physics right of the crankshaft to the shaft, tube and strut. This should be perfect.

 

[Prairie Schooner]

Quick update: We’ve been grinding away (in some cases literally). The strut is back in, the bottom is painted.



Once the strut was in proper relation to the stern tube we realized the engine was too far off alignment and the mounts needed to be moved. It was more than I felt I could handle so we’ve hired a mechanic to do that. They pulled the engine and while we’re in there we’ve taken the alternator and starter out for testing and cleaning, also the prop and shaft, new coupler, a drive saver added, new dripless seal, cleaned heat exchanger and new zinc, exhaust riser repair, derust and paint the oil pan, new hoses, and new fuel filter. Supply chain problems and mechanic vacations meant the engine wasn’t finally bolted in place until yesterday. They have more to go. I’ve been busy with a long laundry list of other work on the boat including replacing or rebedding all the clutches and cabin top winches, filling bulkhead analog instrument holes and installing digital displays, bilge hoses, etc., etc. . . .



Maaaaaaayybe we’ll get in the water sometime next week. A consolation prize is that fall sailing in New England can be some of the best. In the meantime it's been fun following all your sailing adventures.

 

[Pete the Cat]

Not standard practice at all. In fact, many more boats have no strut anode than do.

Regarding the shaft anode protecting the strut- that doesn’t happen. The strut is electrically isolated from the shaft by the cutless bearing.

Unless the strut is grounded internally (as many Tartan and Sabres were done at the factory) to a bonding wire that connects to the engine and any through hull fitting with a motor on it. This was standard practice at one time in the Tartan factory. I am not suggesting that this is a good or bad idea, just that I have worked on enough boats to see this practice was done during the 80's.

 

[bgary]

the cutless bearing rubber insulates the strut from the shaft, so I'm not sure if the prop shaft zincs have any positive effect on the strut.

I've been curious about this too.

The idea of zincs is to allow galvanic action to affect the sacrificial part. Especially import to have a continuous path from the engine to a zinc.

So the idea of a zinc on the strut has always confused me - the only contact that the strut has with any dissimilar metals is the stainless bolts that hold it in place. There's nothing grounded to the strut inside the boat (in fact, the top end of the strut is glassed in and out of contact with anything but the fiberglass and the bolts), and the shaft (as you note) is insulated from it.

I have a zinc on my strut but... I've never really understood why.

 

[Loren Beach]

So the idea of a zinc on the strut has always confused me - the only contact that the strut has with any dissimilar metals is the stainless bolts that hold it in place. There's nothing grounded to the strut inside the boat (in fact, the top end of the strut is glassed in and out of contact with anything but the fiberglass and the bolts), and the shaft (as you note) is insulated from it.

I have a zinc on my strut but... I've never really understood why.

Nicely put. Our boat came from a salt water environment, and had never had a 'zinc' on its strut. When we bought the boat the old two blade bronze prop was pink in places from electrolysis, and I could carve little bits off the blades with a pocket knife. The surveyor's report said that the seller should replace the prop, and they did so.
Same strut still in place with no "pink' areas, after all these years. We do keep an (aluminum) anode on the shaft, tho.

 

[Prairie Schooner]

I've been curious about this too.

The idea of zincs is to allow galvanic action to affect the sacrificial part. Especially import to have a continuous path from the engine to a zinc.

So the idea of a zinc on the strut has always confused me - the only contact that the strut has with any dissimilar metals is the stainless bolts that hold it in place. There's nothing grounded to the strut inside the boat (in fact, the top end of the strut is glassed in and out of contact with anything but the fiberglass and the bolts), and the shaft (as you note) is insulated from it.

I have a zinc on my strut but... I've never really understood why.

We opted to not add an anode to the stut. However, I did use bronze screws instead of stainless. There will be two aluminum anodes on the shaft.

 

[Nick J]

The yard got the strut out today. They used a hole saw to hog out most of the material. It looks like it went well. I was a little late to catch them before they went home so I'll have to follow up tomorrow to see the actual strut