# Mismatch between stern tube OD and prop shaft/standard stuffing box size



## jameswilson29 (Aug 15, 2009)

It appears that Pearson built the 28-1 with what is now a mismatch: a 1 ½" diameter smooth fiberglass stern tube and a 7/8" propeller shaft. The standard stuffing box size tube for a 7/8" propeller shaft now has an ID of 1 ¾", not an ID of 1 ½", which is now the standard size for a ¾" propeller shaft. Photo link: SailNet Community - jameswilson29's Album: Winter repairs: replace stuffing box hose - Picture

Here are my options, as I see it:

1. Buy stuffing box for ¾" shaft and re-bore to 7/8" size (problem: will probably never pack right and will weep excessively or overheat);

2. Epoxy prefab fiberglass tube with 1 ¾" OD and 1 ½" ID to existing stern tube to increase diameter;

3. Lay additional fiberglass to existing stern tube to increase diameter;

4. Buy and install ¾" propeller shaft and alter all lower end parts (too expensive); or

5. Clean and wrap existing stern tube with silicone tape to add ¼' to diameter and/or coat with 3M 5200 sealant before applying hose to tube for better seal (problem: not structurally sound and creates difficulty with next removal of tube?).

Any other ideas? What is the best way to rectify the mismatch?


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## Maine Sail (Jan 6, 2003)

Why do you need a new packing gland? Normally these things will out last the boat and all that needs replacing is the hose.


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## Lake Superior Sailor (Aug 23, 2011)

Why change the box: it's made of brass ,just clean it up, Replace the hose & repack it. This lasted how long? It's tested, If its not broke don't fix it!-Dale


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## jameswilson29 (Aug 15, 2009)

Maybe my approach was mistaken. The packing gland was quite corroded and appeared somewhat stripped (photo: SailNet Community - jameswilson29's Album: Winter repairs: replace stuffing box hose - Picture ). Since I was replacing the hose and the propeller, I thought it was a good idea to replace the entire packing gland (and the cutlass bearing) while I was doing the work.

The stuffing box was leaking excessively. From the work I have done so far, it appears that there was not sufficient room to re-pack it without removing it from the propeller shaft, probably due to the drivesaver added to the coupling and the length of the original coupling (I hope the new shorty coupling will cure that problem). I doubt it was properly serviced in the 15 years since the boat was repowered with an inboard diesel in place of the A4. I will take a photo of the old flax packing when I remove it.


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## dabnis (Jul 29, 2007)

jameswilson29 said:


> It appears that Pearson built the 28-1 with what is now a mismatch: a 1 ½" diameter smooth fiberglass stern tube and a 7/8" propeller shaft. The standard stuffing box size tube for a 7/8" propeller shaft now has an ID of 1 ¾", not an ID of 1 ½", which is now the standard size for a ¾" propeller shaft. Photo link: SailNet Community - jameswilson29's Album: Winter repairs: replace stuffing box hose - Picture
> 
> Here are my options, as I see it:
> 
> ...


Not sure about the concern of the ID specs as long as the OD"s are close enough for the hose to accommodate? also, maybe it is just the photo but it looks like the engine may be mounted way too low? Is the cutlass bearing wearing evenly front to back? If uneven shaft alignment may be off? Were there any problems with the existing setup?

Dabnis


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## jameswilson29 (Aug 15, 2009)

There were no problems with the existing setup, except that the stuffing box hose was cracked, and replacement was recommended by the surveyor.

The engine ran great, although less vibration would be preferable.

The stuffing box was leaking too much, probably 15-20 drops a minute.

I have only owned the boat for 2 months so I did not check alignment; I have been more concerned with the surveyor's recommendations.


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## overbored (Oct 8, 2010)

Wrap with fiber glass is the best way to increase the diameter. Pss makes a dripless packing that will fit 1 1/4" up to a 2/14" stren tube for a 7/8" shaft. dripless is the only way to go
PSS Small Shaft Seals | PSS Shaft Seal


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## jameswilson29 (Aug 15, 2009)

Thanks for all your responses, and thanks particularly for the new option of a dripless seal - that will be my solution to the problem.

(It also solves another P28 potential problem - galvanic action on the keel-stepped mast from salt water in the bilge.)


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## tommays (Sep 9, 2008)

The box could be bad but it sure looks like just a bit of normal green stuff and should clean up like brand new ?


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## Maine Sail (Jan 6, 2003)

tommays said:


> The box could be bad but it sure looks like just a bit of normal green stuff and should clean up like brand new ?


Ditto! I've yet to see one my bench grinder and brass wire wheel could not make look like brand new in about 5-10 minutes..


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## jameswilson29 (Aug 15, 2009)

Oh no, not more tools and equipment to buy, the parts are already wiping me out...


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## dabnis (Jul 29, 2007)

jameswilson29 said:


> There were no problems with the existing setup, except that the stuffing box hose was cracked, and replacement was recommended by the surveyor.
> 
> The engine ran great, although less vibration would be preferable.
> 
> ...


"Vibration"? In or out of gear or both? If in neutral, maybe loose or deteriorating motor mounts? If only in gear, maybe shaft alignment or out of balance prop or bent shaft?

Dabnis


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## jameswilson29 (Aug 15, 2009)

Both, but not bad compared to most inboard marine engines on sailboats. Worse as one approaches WOT. Overall the engine runs well and was the focus of the last owner's repair efforts.

Yes, one of the motor mounts is deteriorating and could be replaced.

I do not know whether the engine was properly aligned. I suppose it was possible the POs had the last coupling fitted and faced to the propeller shaft when the boat was repowered 15 years ago, but I do not have any evidence of the work being done.


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## dabnis (Jul 29, 2007)

jameswilson29 said:


> Both, but not bad compared to most inboard marine engines on sailboats. Worse as one approaches WOT. Overall the engine runs well and was the focus of the last owner's repair efforts.
> 
> Yes, one of the motor mounts is deteriorating and could be replaced.
> 
> I do not know whether the engine was properly aligned. I suppose it was possible the POs had the last coupling fitted and faced to the propeller shaft when the boat was repowered 15 years ago, but I do not have any evidence of the work being done.


Maybe a combination of the motor mount and the shaft? From the looks of the picture: SailNet Community - jameswilson29's Album: Winter repairs: replace stuffing box hose - Picture it looks like the engine may be too low? I would think that the shaft should be pretty close to parallel with the shaft tube (log?) and that the cutlass bearing is pressed into the tube. However, all that being said, if the cutlass bearing is wearing evenly and the only problem was excessive leaking of the packing gland, which can be fixed, maybe the vibration is "normal".

Dabnis


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## jameswilson29 (Aug 15, 2009)

I see what you mean by your observations of the propeller shaft angle.

I plan to align the new set up when it is back in the water in the Spring - would be nice to have a smooth running engine for those dreaded long periods of motoring on windless days.


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## CalebD (Jan 11, 2008)

In my experience with inboard diesel engines vibration of the hull is normal and to be expected. Vibration is due to the nature of the diesel engine. Vibration from the drive train is not normal.
My atomic 4 runs a lot smoother then any diesel powered boat I've been on.


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## hellosailor (Apr 11, 2006)

James-
Spring for a Dremel tool set and some extra brass brushes for that. It isn't a bench grinder but it is very flexible and can do small polishing jobs like this very nicely. I think a lot of us waited many years too long before buying a Dremel set, but no one ever regrets it when they finally do. And it doesn't take up much space, or budget, in the larger scheme of things. DO make sure to wear eye protection when you are using the wire brushes though.


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## dabnis (Jul 29, 2007)

jameswilson29 said:


> I see what you mean by your observations of the propeller shaft angle.
> 
> I plan to align the new set up when it is back in the water in the Spring - would be nice to have a smooth running engine for those dreaded long periods of motoring on windless days.


Just thought about the "Drivesaver", wonder why it was installed?, alignment problems maybe? If it shows signs of deteriorating or stressing it may be being overworked. I suppose they are installed to reduce vibration but then they become another link that can fail as happened with the Bumfuzzles. From Pat's log, June 27, 2011.

bumfuzzle | june 2011

"I opened up the compartment and was looking around, everything looked okay, but then I noticed the boat slowing down and the motion getting rockier. I looked further back at the transmission and there it is. The shaft coupling snapped. The prop shaft was no longer attached to the engine, and couldn't be."

Dabnis


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## jameswilson29 (Aug 15, 2009)

After removing the plastic break plate, inserting a shaft puller, and trying to remove the coupler from the shaft for an hour or so, I finally just cut the propeller shaft:http://www.sailnet.com/forums/members/jameswilson29-albums-winter-repairs-replace-stuffing-box-hose-picture601-propeller-shaft-cut-two-angle-grinder.html

New propeller shaft and cutlass bearing on the way, along with new coupler and newer propeller. Basically, I am now replacing all parts aft of the transmission...


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## Ajax_MD (Nov 24, 2009)

CalebD said:


> In my experience with inboard diesel engines vibration of the hull is normal and to be expected. Vibration is due to the nature of the diesel engine. Vibration from the drive train is not normal.
> My atomic 4 runs a lot smoother then any diesel powered boat I've been on.


Diesels on smaller boats are often only 1 or 2 cylinders, so they tend to vibrate like a V-twin Harley Davidson motorcycle engine. The Atomic-4, being (duh) 4 cylinders, has more "men rowing the boat", so it's smoother.
My buddy's 35 footer has a Yanmar 3 cylinder, and it's quite smooth.

Sorry to hear that you had to cut the shaft. When you install all the new gear, you will (or should) use a feeler gauge around the coupler to ensure that the engine and shaft are perfectly in-line to eliminate any vibration. Basically, you put the feeler gauge at various points around the coupler, and adjust the engine position on it's mounts until the gap is consistent all the way 'round.

I will be performing this check this winter myself.


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## Maine Sail (Jan 6, 2003)

jameswilson29 said:


> After removing the plastic break plate, inserting a shaft puller, and trying to remove the coupler from the shaft for an hour or so, I finally just cut the propeller shaft:SailNet Community - jameswilson29's Album: Winter repairs: replace stuffing box hose - Picture
> 
> New propeller shaft and cutlass bearing on the way, along with new coupler and newer propeller. Basically, I am now replacing all parts aft of the transmission...


That is often your best move with a solid coupling. Unless I can get a gear puller between the gear box and coupling I will not even attempt to remove a rusted on coupling beyond a gentle "press".. It is just not worth ruining a gear box over.

I have seen three ruined gear boxes in the last 12 months all done by owners trying to save a few pennies and using the output flange to try and remove the coupling.

I simply check the output flange with a dial indicator and they are often bent well beyond .003" in the "pressing off" part of the removal, if the output flange was used as the "press".










Your stuffing box will clean up like new with a drill and brass wheel or bench grinder and brass wheel Be sure to wear a dust mask as you don't want to breathe that stuff...


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