Re-pack stuffing box - How often?

[svfinlandia]

Originally Posted by tkeithlu

Might it be a good time to get over the obsession and replace the stuffing box with a shaft seal? Then you'll have time to obsess over something else that's more fun.

Stuffing boxes have a wierd status in the world of mechanical devices. The "right" condition for them is a sloppy situation, with the stuffing not quite sealing, and slightly leaking. If you get them to actually do the job of keeping the water out, you've over tightened them. That's easy to do, and then they need adjustment again. Do it a few times, and they need restuffing. If you have any tendency to obsession, as I do, they are a trap for your brain. A shaft seal does the job, doesn't leak, and needs next to zero maintenance. I think that stuffing boxes should be retired wherever possible, even if just for our mental health.

Shaft seals are fine until they break, burst.
You can ask a friend of mine who barely made it to the dock before his boat sank in the ICW in Florida.
I replaced the packing on my stuffing box 10 years ago and it is still dripping one or two drops a minute while running without any adjustment and something like 3000 hours on it, but if you’re worried about it, replace it. It can be done with the boat in the water.

Al, S/V Finlandia

[moseriw]

Stuffing boxes have a wierd status in the world of mechanical devices.

Well, the stuffing box was the very first solution to enable proper through hull shafts and it worked for 200 years now. Close the box when you leave the boat for winter break and open it when you use the boat.

Just a drop or two every minute an everthing is perfect. If it is not you stuff in one more layer and it is OK.

If you cannot properly stuff another layer then it is time to get the old stuff out. If you have experience you can do it in the water if you are prepaired and quick. If not find a good mechanic.

I am sure that the stuffing box is the simplest and best solution money can buy. Everything else results in broken shaft seals or gear boxes which have to be repaced every two years and such.

[Searles]

Don’t forget to grease the stuff box ,a grease injection point just aft of the throat of the stuff box,a little grease in the tube, the water will push the grease to the packing ,most packing fail because it dries out.⛵️⚓️

[moseriw]

Originally Posted by Searles

Don’t forget to grease the stuff box ,a grease injection point just aft of the throat of the stuff box,a little grease in the tube, the water will push the grease to the packing ,most packing fail because it dries out.⛵️⚓️

Sorry never heared about greasing. The stuffing rope itself has paraffine in it an this is what tightens it.

[Bowdrie]

Originally Posted by Searles

Don’t forget to grease the stuff box ,a grease injection point just aft of the throat of the stuff box,a little grease in the tube, the water will push the grease to the packing ,most packing fail because it dries out.⛵️⚓️

In the "old days" it was not un-common to fill the whole stern tube with grease until it reached the grooves in the Cutlass bearing.

[pcmm]

Originally Posted by Searles

Don’t forget to grease the stuff box ,a grease injection point just aft of the throat of the stuff box,a little grease in the tube, the water will push the grease to the packing ,most packing fail because it dries out.⛵️⚓️

No grease in the stuffing box. If you block the water the packing will burn up. The water lubricates the packing

[whiskyjack]

I too have obsessed over stuffing boxes. I was taught to wind down the stern tube greaser until I met resistance each day that engine was in use. I did that on my boat when it was newly built, but I had the same problem described on this thread.... either leakage or overheating. Also I never got resistance. Then I looked at the big picture. I have a metre or so of mild steel sterntube with a cutless bearing one end and a stuffing box at the other. Grease going into the stern gland has an easy escape into the sterntube. Isn't the correct solution to have the sterntube full of grease, the stuffing box is then holding back grease rather than water (needs less preload and no water leakage!). Importantly the whole stern tube is now protected from sea water corrosion. To implement this, about 10 years I pumped as much grease as I could into the stern gland while the boat was out of the water, and the stern gland has been trouble free ever since! no water leaks no overheating. Tighten the stern gland greaser once a week and think of England.

[saillr]

I don't know why people still consider Dripless Systems. They can fail and it will sink your boat unless you are there.

The only packing to use and if you are having trouble adjusting the drip, it's likely you already have it - is Teflon (PTFE) infused packing. The correct way to adjust it is to tighten the nut until the drip just stops and then tighten up the locking nut. After a few hours of motoring check if the Box is dripping, tighten slightly until the drip stops. You can easily check to see if the Box is warm by putting your hand on it while running. It should be totally cool to the touch. This is the best "Dripless" material.

I have used this in my last two boats over 35 years and have a completely dry bilge. Teflon (white packing) is amazing. Use it and forget it. Teflon packing is not intended to drip.

[MJH]

Originally Posted by AnglaisInHull

I'm back to my stuffing box obsession. Last season I was having a bit of trouble adjusting it the way I like it and wondered if it's time to repack.

I don't think it should be time - the whole thing was replaced when the engine was replaced, about 250 engine hours ago. On the other hand, that was more than 10 years ago in real time.

Does calendar time matter? How often should I expect to do this?

Thanks for any insights. No, I didn't search for other threads on the subject; am going through a lazy period (we call it "winter" in this region).

You obviously have some fear of changing the packing...so did I the first time. Keep it simple; you don't want to put yourself into a position that forces a unscheduled change WITH THE BOAT IN THE WATER. Bite the bullet and put the suffing box on your haul-out To-Do list...for me that is every two years. That way I know the packing is good and won't worry about it...its just part of staying ahead of the boat. After a couple times you won't think twice about completing the maintenance. What is also important about periodic changes is to keep the bolts free from built-up debris making the nuts hard to turn.

~ ~ _/) ~ ~

[drcot3]

Put a drip tray underneath then bilge stays dry. I have stuffing boxes on a twin 265HP diesel engine motorboat, doing 50+ hours a year. Replaced stuffing 20 years ago. Then good to go when I am ready. Tightened when needed but avoid the sin of overtightening. I will replace this year especially as the stuff is so cheap, just carry some new rope/flax/synthetic onboard in a sealed vacuum bag, usually as sold. If so worried check bilge for seawater every so often & have bilge warning lights/buzzers. I have become very complacent, but replace the outer rubber hose more often, carry hoses/impellers/belts/filters/jubilee clips/pumps/etc spares like me. Motorboats have more space to store thats why I need a bigger boat. Stuffing boxes are simple just slow drip when running & they seal after a day or two when moored/anchored, just adjust if needed, better more sea water than causing the shaft to go blue.

[saillr]

I see @Clivevon suggested going to the thread -

https://www.sailnet.com/threads/ques...acking.331022/

You will note others having trouble adjusting the drip on Teflon packing. They cannot get the box to drip like on the older grease impregnated flax.
That's because you don't need to drip with Teflon.

Try it. Its the best and cheapest dripless system on the market.

[GrowleyMonster]

Originally Posted by Barkingmad

More than 10 years, I'd be thinking about replacing the stuffing box hose. Check engine alignment at the same time, probably due after 10 years as well.

This.

If you find yourself tightening your stuffing box often, you may be overtightening. You might also have alignment issues or shaft erosion/corrosion. If you are reasonably careful you can cut another ring of packing and add it right over the old, for now. Don't overtighten. You should see an occasional drip when the shaft is not turning, a fairly rapid drip when it is turning. A steady trickle is a bit much. Water lubricates and cools the packing, so you need some water to pass through. I usually find an annual tightening about right, but then again I don't motor much, just ins and outs, anchoring, locks, and bridges.If the wind don't blow, I don't go, and that's fine with me.

[MicHughV]

I agree with the above.....The newer synthetic teflon and/or graphite loaded packing materials are a good upgrade from the old waxed flax.

The common rule of thumb (for the old style waxed flax) is to tighten the adjusting threaded cap to allow a slow drip when the engine is running..maybe 1 drip every few minutes.....but no drip when the engine is not running.

The newer synthetic material apparently does not require that. I've used it, I run the engine in gear at the dock and tighten the stuffing box gland fitting until there is no drip. Never had an issue with the stuffing box getting too hot, etc...I usually grease the end cap so it turns on easily. It has a locking ring to keep it in place. Once in a while, I'll tighten this a tiny bit.

I've also had the PSS shaft seal, but those can be iffy. It requires sufficient water pressure to push the rotating disc against the PSS counter part. Some boats have a shallow bilge, so the propshaft is not very deep below the water...which in turn, means not much pressure on the bellows. I never had an issue with mine, as my prop shaft was quite deep underwater.

If access is simple....I'd probably put my vote on the stuffing box with synthetic teflon...

[nofacey]

If it’s bugging you, just do it. Easy job.

[Bowdrie]

Originally Posted by whiskyjack

Then I looked at the big picture. I have a metre or so of mild steel sterntube with a cutless bearing one end and a stuffing box at the other. Grease going into the stern gland has an easy escape into the sterntube. Isn't the correct solution to have the sterntube full of grease, the stuffing box is then holding back grease rather than water (needs less preload and no water leakage!). Importantly the whole stern tube is now protected from sea water corrosion. To implement this, about 10 years I pumped as much grease as I could into the stern gland while the boat was out of the water, and the stern gland has been trouble free ever since! no water leaks no overheating. Tighten the stern gland greaser once a week and think of England.

Yep, the old guys knew a thing or three.
So many of the modern boats don't really have a "stern tube", where the prop is just behind a fin keel with a strut bearing.
But yes, a metre of stern tube can work just fine full of grease.
And, for those without a stern tube of any consequential length theirs's no reason today to still be using the old waxed flax packing, the Teflon stuff is so much better.