shaft coupling

[alcodiesel]

If y'all would educate me:

1. why do I want a split coupler?

2 why do I want a dripless stuffing box?

I think I know- I want confirmation or not

Thank you fellers

[ndutton]

Addressing #2, these three posts are from the same thread 8½ years ago:

https://www.moyermarineforum.com/forums/showpost.php?p=80962&postcount=6

followed by

https://www.moyermarineforum.com/forums/showpost.php?p=80966&postcount=7

and finally

https://www.moyermarineforum.com/forums/showpost.php?p=80971&postcount=10

[joe_db]

If y'all would educate me:

1. why do I want a split coupler?

2 why do I want a dripless stuffing box?

I think I know- I want confirmation or not

Thank you fellers

1. why do I want a split coupler?
Because they are easier to work with. I always suggested my customers get them back when I did that kind of work.

2 why do I want a dripless stuffing box?
Because they don't drip! The case for them may not be as strong now as it was before Teflon packing came out, I have never tried that. I have had one since about 1985 or so and like it.

[alcodiesel]

Ok so maybe I don't want a dripless.
What about the split coupler?

[ndutton]

I have no experience with the split coupler so I have no business commenting on it. However, my experience and opinion of the standard coupler is this: In the 100+ engines and drivelines I installed in the 1970's during my employment in the sailboat industry I never installed a shaft by beating it into the coupler. The current practice of a fit so tight it needs a hammer for installation is bad form in my opinion. I think it was MMI forum member Al Schober who said the keyway holds the torque, the set screws hold the thrust or something to that effect and I endorse the assessment wholeheartedly. I would even add to it that the coupler holds the alignment. Such a tight fit risks hammer damage to the transmission internals too.

On the bench I would dress the inboard shaft ends with a hand file carefully until the coupler could be slipped on by hand. With it in place and the set screws removed from the coupler I would mark dimple locations on the shaft, remove the coupler and drill generous dimples into the shaft on a drill press. Final assembly would be to slide the shaft into the the coupler (mounted on the engine) until the dimples were visible in the set screw holes, install and tighten the set screws and secure them with seizing wire.

Never a problem and as I said earlier, hundreds of boats.

[Al Schober]

NO, do not 'dress' the end of the shaft to fit the coupling! The coupling is made out of cast iron and will corrode. The shaft is stainless or perhaps bronze - stable materials. The reason the fit is tight is that the bore of the coupling has corroded.
I recommend you get a dowel about 1/8" smaller than your shaft, wrap some 80 grit around it, then clean up the inside of the coupling. It won't take much work as you're removing rust, not good metal.
Again, you need the drill recess in the shaft to take the cup point of the set screw. Measure the cup point and you'll know what size drill to use. I recommend a cobalt drill for cutting stainless - HSS will just burn. I also recommend a drill press!

[alcodiesel]

Can we circle back to dripless for a minute?

I failed to mention access to the stuffing box to adjust the packing, for instance, is very difficult if not impossible (for me) with the engine in place.

Thoughts?

[joe_db]

Can we circle back to dripless for a minute?

I failed to mention access to the stuffing box to adjust the packing, for instance, is very difficult if not impossible (for me) with the engine in place.

Thoughts?

I love mine! It has been not leaking for over 35 years
* well actually I am on #2, about 8 years ago I got a new shaft and replaced it while everything was apart.

Whenever we ordered a shaft and coupling that was not a split coupling we had the prop shop fit the shaft and coupling for us, they made sure it wasn't too loose or too tight. The split couplings are so much easier to get on and off we always tried and use them.

[Al Schober]

IMHO, the face type seals are good. Our Navy uses them on submarines which see considerably more severe service than our boats. But, two things to consider.
First, they like clean water. Silt or grit in the water will wear them out. Navy addresses this by pumping filtered sea water into the shaft tube aft of the seal. I would recommend doing the same. Just tap into the output of the raw water pump, filter it, and run it to the seal. I believe most of the face seal units have a fitting for this.
Second, the rotating part of the seal is held in place by the shaft and is spring loaded against the fixed part. If the shaft moves forward, the seal faces will open up and allow water (a LOT) into the boat. This can happen if your engine is on resilient mounts and they're not up to resisting full thrust. So after installation, give the engine a good push and see what happens.

[sastanley]

To each his own...I have the graphite packing in my traditional stuffing box, and it is almost dripless. I would personally be worried about rubber bellows and burpers and stuff in an area I can't readily access. The amount of sea water that drips in thru the stuffing box almost evaporates before I can sponge it out of the bilge.

[Dave Neptune]

3 types

In my 45 plus years of operating a sailboat with an inboard engine I have used both dripless and packing styles in 3 ways.

First is the packing style packed with "flax" type seals. These are a PIA as they do leak often albeit not much, They do require constant monitoring and adjustment.

Second, the packing style with the synthetic packing is a big plus over the above. It is a bit more difficult to get adjusted but once adjusted it offers many years of service with very little dripping as per Shawn. All that is required for the most part is monitoring just to be "sure".

Third is the dripless, it is not maintenance free as the water line for cooling must be checked often for flow as it is a small line and easily can plug up. Al's point of filtering is a good idea especially in silty conditions. It also requires annual lubricating under the bellows.

Point is no matter what you choose it will require "checking and maintenance" so if this is a problem I strongly suggest creating an access port for maintenance whatever you choose.

Dave Neptune

[joe_db]

In my 45 plus years of operating a sailboat with an inboard engine I have used both dripless and packing styles in 3 ways.

First is the packing style packed with "flax" type seals. These are a PIA as they do leak often albeit not much, They do require constant monitoring and adjustment.

Second, the packing style with the synthetic packing is a big plus over the above. It is a bit more difficult to get adjusted but once adjusted it offers many years of service with very little dripping as per Shawn. All that is required for the most part is monitoring just to be "sure".

Third is the dripless, it is not maintenance free as the water line for cooling must be checked often for flow as it is a small line and easily can plug up. Al's point of filtering is a good idea especially in silty conditions. It also requires annual lubricating under the bellows.

Point is no matter what you choose it will require "checking and maintenance" so if this is a problem I strongly suggest creating an access port for maintenance whatever you choose.

Dave Neptune

My seal does not have a water line and requires no routine maintenance at all. Not having a hose to either vent air or have water injected into it means the seal can trap air, so when the boat is hauled or after scuba diving that might get air up in it you need to burp it.

[DDO]

I survived that haul-out...

Had no room for dripless, so here's the traditional, with the precious split hub... easy to assemble myself, and fun with feeler gauges and more. But I had waited to long to notice the little "wobble" so it had time to grind away on the shaft log -- it had to be re-fiber-glassed (?). I pulled off the old stuffing box hose to see it was just about to open up a hole to the sea. Yikes. So get on it and submit you photo of shiny new drive train? Note I have no room to replace stuffing... I have to block the boat higher and pull it all apart ha ha to do that.

[alcodiesel]

I think I have stuffing box envy.

[alcodiesel]

She's in the yards now. I'm having someone do this job- to much contortion for me.

Tomorrow they start work on it. I have all replacement parts except the shaft: split coupler, regular stuffing box, even a cutless if needed.

I'll report back how it goes.

Thanks fellas, especially Neil for the suggestions.