dripfree packing

[DuncanvdH]

On my visit to the US I bought some of the 'dripfree packing' material that looks like green putty/clay. As described in the book by Nigel calder the stuff is put between two rings of conventional flax packing and should provide a dripfree seal, without the need for grease.

However, my stuffing box also incorporates the forward bearing of the propshaft.
After the bearing a flexible coupling connects to the gearbox.

That bearing should be greased right? There is a grease line fitted to the bearing.

Does this mean I should not use the dripfree packing? I am confused.
I would like to avoid the greasy mess I had before...

duncan

[sdowney717]

http://www.e-marine-inc.com/products...g/packing.html

GFO® fiber dripless packing is a braided propeller and rudder shaft packing that you can install and forget about. After 15 years of successfully handling demanding industrial pump applications, it's now proving itself in the marine field, too. It's already being used by the US Navy and Coast Guard and many commercial work and fishing fleets. And, it's approved by the American Bureau of Shipping. Easy to install No grease, no mess. Just cut the rings to length and install them in the stuffing box. Make maybe one adjustment to the gland follower after a short run-in, and never tinker with the stuffing box again. You'll rarely need to make any adjustments, and the Gore dripless packing will last for years.

[jackster]

Duncan,
Hard to say without seeing the bearing, but that won't stop me from offering my opinion in the spirit of a little experience freely offered and worth every cent.
The bearing, unless water cooled(which will have a hose in and out for water) is a seperate fixture from your stuffing box, which is for keeping your shaft from leaking.
It is either a universal joint or some form of pillow bearing, I guess, and if it has a grease(zerk) fitting should be greased. Although, if it is throwing a lot of grease, may be worn and in need of replacing, or you are using too much force when filling.
Just my opinion from a great distance, good luck with your project!

[kc8pql]

FWIW, I used the green putty stuff for a couple of seasons. Never could get the stuffing box adjusted properly. It either leaked too much or ran hot. I gave up last year and installed the GFO packing. It took one adjustment after about a two hour run in and has been perfect since.

[gert]

What about these things?


http://www.shaftseal.com/categories

[eastern270]

I have purchased the GFO packing and will use it when the boat is finished being built. I heard people using it will use nothing else. The greens stuff I heard has alot of problems. I also have a dripless shaft seal just in case the GFO doesn't work as advertised but have read about some horror stories with those also. The convention packing gland with spud nut and GFO packing is definately the lesser expensive way to go. I believe it will also be easier to service when the need arrives. The dripless shaft seals use orings between a collar and the prop shaft and require you to take off the shaft coupling to slide new ones on if you need to replace them.

[Lew Barrett]

I have purchased the GFO packing and will use it when the boat is finished being built. I heard people using it will use nothing else. The greens stuff I heard has alot of problems. I also have a dripless shaft seal just in case the GFO doesn't work as advertised but have read about some horror stories with those also. The convention packing gland with spud nut and GFO packing is definately the lesser expensive way to go. I believe it will also be easier to service when the need arrives. The dripless shaft seals use orings between a collar and the prop shaft and require you to take off the shaft coupling to slide new ones on if you need to replace them.

Not if you slide a replacement seal onto the shaft prior to installation. The replacement lives happily and rather unobtrusively on the shaft until it is needed. At that point, the old one is cut away and the new one slipped into it's place. That's the way they are generally installed.The new dripless units are very reliable, but there's no question that a conventional system is cheaper and stone simple. But traditionally, they leak; discounting the products being discussed here, of course!

[eastern270]

Not if you slide a replacement seal onto the shaft prior to installation. The replacement lives happily and rather unobtrusively on the shaft until it is needed. At that point, the old one is cut away and the new one slipped into it's place. That's the way they are generally installed.The new dripless units are very reliable, but there's no question that a conventional system is cheaper and stone simple. But traditionally, they leak; discounting the products being discussed here, of course!

I have the same exact one (pss) that is in the picture in the post above. If you notice that the orings are in a groove in the inside diameter of that sleeve which prevents being able to take them out or install them while on the shaft without ruining them. There are other brands with seals that are able to be replaced with spares that were installed on the prop shaft from the beginning. That brand (pss)also has 2 orings on it with the locking set screw between them. It spins with the prop shaft and I would anticipate that they probably don't wear from anything other than getting brittle or dry rot for some reason. I would agree that they seem very reliable but I was just relaying messages of the horror stories I have heard from them. I may even end up using mine instead of the packing gland that I have. I think the lasdrop is the one with the replacable seal without removing from the shaft.

[donald branscom]

Forget all that stuff.
Forget all the packing materials ,forget the fancy multi hundred dollar systems that you will not be able to repair when not at home.

Fill the stern tube with polypropolene grease by attaching a grease fitting to the stern tube inside the boat.

The packing and nut then is just insurance.

It will never leak a drop.

i know it works because i have done it to two of my boats, it is not a myth and not just a theory.

[donald branscom]

What about these things?


http://www.shaftseal.com/categories

Too expensive, too complicated, and too hard to get replacement parts. If there are any. What if the little hose starts leaking. Just another potential way for your boat to sink.

What if that little hose barb breaks off?
Plastic parts! No way!

That is like a Ford Explorer with a plastic clip holding on the shift lever to the trans. Crazy!!!



Think simple, less parts.

[donald branscom]

Bullet proof method.

Stern tube packed with polypropolene grease.

[eastern270]

do you get grease squeezing thru either end or a oil slick in the water ? Just curious. I heard of this done before.

[gert]

That is like a Ford Explorer with a plastic clip holding on the shift lever to the trans

actually....

I'm curious about the stern tube full of grease too

[WX]

Me too!

[WX]

Here's a link to an Australian supplier for the GFO packing.
http://www.industrialgaskets.com.au/...b6c042c346f90b

[py]

Thanks WX! Its even in my neck of the woods. Perfect.

[WX]

No worries, py. I don't think I've seen you on here before...you must lurk abit

[donald branscom]

do you get grease squeezing thru either end or a oil slick in the water ? Just curious. I heard of this done before.

NO.

When you first fill the tube with grease you want it to come out the stern bearing just to know it got all the way to the end of the tube.
Just remove the excess .
The water pressure is trying to push it into the tube.

I never saw the slightest sheen of grease on the water around my boat.
I was a live aboard and did a look around inspection daily.

[DuncanvdH]

questions questions...
So I should toss the green clay and get the GFO packing?
I am still surprised that both these 'miracle' products are not available here.

What on earth is polypropolene grease? Will this also lube the bearing?

I will post pictures of the bearing/stuffing box setup. It got slightly damaged during the initial casting in of the stern tube, but I have a friend that can supply me with a replacement.

If I replace the setup with a water lubed setup. What will replace the bearing?
The rubber bellow does allo lateral movement, as opposed to the rigid stuffing box setup.

Duncan

[py]

WX, I guess I listen more than I talk-but I have a few posts to my name.
Phil

[Paul Eaton]

Donald,

What sort of bearings were you using? White metal? "Rubber"? Was heat build up a problem - water is a good coolant but not such a good lubricant. Grease is the other way around. Also what sort of shaft material? Sounds like a oxygen depleted environment - not so good with SS.

By polypropylene grease do you mean one of the synthetic greases with PAOs (Poly alpha olefins)? Which one do you use?

I have a displacement launch (almost completed) with white metal bearings, no aft seal, max RPM 450 with a 1 1/4 aqualloy 22 shaft, no water scoop on the aft bearing. I have been concerned about wear of the aft bearing and your suggestion sound a possible solution.

Thanks

[donald branscom]

The aft cutlass bearing is fiberglass and rubber with grooves for the water.
It is secured with a set screw.

The polypropolene grease is just wheel bearing grease for boat trailers and you can get it at most auto stores.

The front bearing(packing) is the standard bronze thing. The stern tube can be steel or stainless. If it is a big boat use a schedule 80 pipe or a tube. there is no weight penalty in that part of the boat.

I do not want to get into a metalurgical discussion about prop shafts but usually the area that the shaft goes thru the stern bearing sometimes gets pitted.
Takes a long time. Also remember that any metal parts below the waterline moving more than 6 knots have a 30% increase in corrosion rates. But like i say just use the regular marine stuff and you will be ok.
Most any boat driveshaft machinining center can help you with those kinds of questions of metal compatability.

The less dissimular metals the better.

[sdowney717]

http://www.vesconite.com/
speaking of bushings, they will custom make cutlass shaft and rudder bushes at a low price. I bought 2 for around 25$

[redbopeep]

Where WERE YOU when I was asking questions about our grease filled stern tube last year?? Oh, I wish you'd posted this. It sounds like you did what our boat's previous owner did. Now we've put in place a water lube system were there was previously a grease fitting. If I'd only known.

NO.

When you first fill the tube with grease you want it to come out the stern bearing just to know it got all the way to the end of the tube.
Just remove the excess .
The water pressure is trying to push it into the tube.

I never saw the slightest sheen of grease on the water around my boat.
I was a live aboard and did a look around inspection daily.

[sdowney717]

does the grease disappear?
it does sound pretty good idea. One problem this might avoid is pitting of the shaft where the flax creates a low o2 environment.
I know on my boat there is a fair amount of water pressure at the stern tube gland. Would the grease work its way forward thru the gland? I suppose you might need to replenish the grease, but when would you know? only at haulout?

[Gary E]

Back in the really old days of the mid 1950's a friend of mine had a scow on the Ohio River. Jim and I were 15 yrs old at that time and he an I changed the old 6 cly engine for a Ford V8. We also installed a new shaft and packing gland. That gland had a grease cup on it, just a turn of the cup each day we went out and that kept the river on the outside of the boat.

[DuncanvdH]

There is very little information on the net on 'polypropolene' grease.
Do you have some brand name or another source?

Duncan

[sdowney717]

I would think marine wheel bearing grease would work
this grease is less likely to emulsify with water

[georgel]

My understanding is that in the "old days" before miracle grease they filled the stern tube with tallow. Cold water turns it hard so it tends tokeep the water out, friction / heat melts it and it is an adequate lube. However it must be installed in a clean stern tube. Old grease will cause it to liquefy and no longer function to block the water.

[soba]

I don't know much about grease packed sterntubes, but I know a little about grease....

Polypropylene greases are pretty rare IME, used for extremely low temp joint grease for excavators and the like. They are made by adding a polypropylene solid to a low temp 12-hydroxyl grease (usually).

"Poly" grease usually means a grease that is 40% or more poly-alpha-olefins (PAOs). These are non-vegetable synthesized esters that have polar properties that make them stick to metal better than goose-s*** to a wool blanket.
The confusion may come from the fact that polypropylene is in fact a polyolefin (propylene being an olefin). However, polypropylene is rather dense and not really flexible enough (as a molecule) to be a lubricant base.

Sorry, I'm not very good at explaining this stuff.

At any rate, if you are going to stuff a tube full of grease, I recommend NOT using a traditional soap-thickened grease such as lithium or moly grease, as petroleum based greases tend to attack rubber seals. If there is any rubber sealing it in, things could get messy in the long run.

Best to use any synthetic-type grease (or "poly" grease) or better yet, silicon greases or (if you can afford it!) a fluoroether grease like Krytox.

In fact, a tube full of Krytox might actually prevent crevice corrosion in this application....hmmm. I'll have to try that...

[Gary E]

Years ago when I had the machine shop I had a contract to make some little triger thingies for releasing bombs from that very fast high flying plane, dont remember it's name, but anyway in that trigger thingie was a needle bearing lubed with a Mil spec grease that was good for very low temps... Bottom line is the stuff was popular with the snowmobile guys because it stuck to their parts, remained the proper viscosity, and didnt wash off easy... Maybe that could be used.

[seo]

It sounds as if the "bearing" that's referred to in the original post is a thrust bearing. Not that unusual in european boats, it's usually a pair of tapered roller bearings, much like a front wheel hub of a rear wheel drive car. One bearing takes ahead load, the other takes astern load.
In a conventional propulsion gear, the thrust bearing is located in the reverse gear, which means that the propeller's thrust is delivered to the reverse gear, then transmitted to the boat via the engine mounts and engine beds. With a thrust bearing at the stern, the shaft from there forward to the engine isn't being asked to carry thrust, and can be a typical sliding spline automotive driveshaft, if you have some reason for that.
In any event, the bearings shouldn't be sprayed with salt water, but the whole system was designed to work with flax packing, so it's probably pretty well sorted out to resist salt water getting into the bearing.
I personally use a "miracle" teflon coated flax packing, which works every bit as well as the regular flax packing.
I think that some ships actually use roller bearing for stern bearings, mounting them in the stern tube, sealed from the outside water by some sort of dripless seal, maybe a neoprene lip seal. A torn seal would be an expensive proposition...

[DuncanvdH]

I am sorry, but it is not a thrust bearing. It is just a bronze-white metal coated bearing, with a grease point. I will get the bearing tomorrow.

Duncan

[donald branscom]

The grease.

Just go to an auto parts store and get grease for boat trailer wheel bearings.

It's red.

read the back of the package and you will see that it is made for a salt water environment.


You do not need to be a grease engineer.

[DuncanvdH]

This is a picture of the bearing:
Housing,packing pressing ring, locking nut, nut

[Sailing Dreams]

I'm with Donald on this one, just fit a conventional packing gland with a greaser which is easy to use (ie in a convienient position). A few minutes maintenance each year is all it needs.

I've used this combination on my last 3 yachts, no problems no leaks and no worries while the boat is left on its moorings.

I've also heard that drip free stuffing is abrasive and leads to early shaft wear (although not personal experience)

As a PS I bought a yacht with the "drip free" type gland a carbon faced seal bearing on a stainless collar, it was 18 months old when I bought the boat and was on my list of must upgrades. sadly I didn't get around to it soon enough. During our first season the carbon bearing surface failed (and yes we did make sure the water lubrication was working) with spectaular results, we were taking about a gallon every 10 minutes, there's no redundancy in the design. Fortunaltly we had an engine driven bilge pump for the 4 hour sail home and lift out!!

The replacement conventional stuffing box and greaser worked like a dream!

[DuncanvdH]

Good to hear that you were able to manage the failing shaft seal.

I am having my bearing refurbished on tuesday. The engine is in a plywood boat, so I dont want ANY water inside, and preferably no grease.
The green putty will be binned.
So should I go fully conventional or is the GFO packing an option?

Duncan