Stuffing box or dripless shaft seals?

[coastalexplorer]

In response to the posting by John Mardall.


It is my understanding that the water hose connection to the PSS seal is only essential IF motoring above Eleven knots is anticipated...or a stave bearing is fitted in the stern tube at the inboard end. otherwise it is optional and the connection tube can be blanked off. Check this with PYI.


Since 2014 the amount of compression on the bellows specified was increased to 1.75" for a one inch shaft. There is a chart to figure out correct installation.

[Boatyarddog]

Originally Posted by NorthernMac

From the research I’ve done for my repower coming up.

Stuffing box drips a few times a minute, if it’s not happy a few time a second, can be temporarily repaired by stuffing whatever into the stuffing box, not prone to catastrophic failure.

Dripless doesn’t drip, but when it does, it can get a little...sporty.

For me I’ll be sticking with a stuffing box with modern stuffing, a few drips a min isn’t really a big deal for me, only keeps the very aft section of bildge wet, and I am not tolerant of the failure mode of the dripless, especially in a boat that could be a good ways from land, your mileage may vary.

Speaking about the bellows, I'd much rather have a 3/8" thick walled multiple layer hose for my packing hose than a 1/16" thick bellows, when something goes bad on those dripless bellows, they are flimsy at best.
Not to mention how much water enters when one is torn at sea.
Keep the packing gland!
SV Cloud Duster

[NYSail]

Not all dripless are the same.

[Bear15]

I went from stuffing box to PSS last year, I was going to Florida anyway from Ontario in March, ordered from Hodges marine in Florida, had it shipped to where I was staying, claimed as part of the $800 allowed when returning to Canada and saved the tax which was only about $35 anyway, 1 1/8" shaft, was about $260 usd, pretty reasonable.

[breezydays]

Another vote here for the Volvo shaft seal. Simple, inexpensive and will almost certainly exceed 5 years use if you grease / burp at the start of each season.

[Gary Mc]

I installed a new stuffing box last spring. Old one worked but was original so quite old. I preferred to stay with a traditional stuffing box since it follows the KISS rule.


You can install new packing with it in the water. Not overly familiar with the PSS seals etc. but feel that a failure might be more challenging to fix.


The hard part was finding a supplier for the old style stuffing box. Found them at Fisheries Supply in Seattle, on line of course.


Good Luck
Gary

[Boatyarddog]

Originally Posted by NYSail

Not all dripless are the same.

I'm familiar with the PSS Brand, they used to have a thicker bellows, but now they are thin.
Who else sells them?
Volvo?
SV Cloud Duster

[MJH]

Originally Posted by LauraleeG

I currently have a dripless shaft seal on my Landfall 38 that is not dripless at all. In fact, when the engine revs higher than 1300 rpms...water POURS in. While in a cruise we spoke to a boat mechanic and he opened the bellows up enough for us to stop bailing water, to sail home... but we need to repair or replace this! Repairing/replacing the bellows is an option, but often finding parts that fit an old system is a fools game with out something else going wrong
The cost to replace it with a dripless shaft seal is about 1000$Cad. Or, we could revert back to a stuffing box ...cheaper by far. What are your thoughts? Which way should we go?

I have considered a dripless seal and decided against it. I read too many stories of those with problems with their dripless seal...I don't ever recall a story about a problem with the normal stuffing box. Keep it simple.

~ ~ _/) ~~ MJH

[jmschmidt]

Dripless is not SINKLESS. I wouldn't have one on my boat.

[degouwb]

Old fashioned stuffing box is the way to go. If it ever drips more then you want , just tighten the thing. The more you know about your boat (and check occasionally ) the better.

[JOHNMARDALL]

Originally Posted by coastalexplorer

In response to the posting by John Mardall.


It is my understanding that the water hose connection to the PSS seal is only essential IF motoring above Eleven knots is anticipated...or a stave bearing is fitted in the stern tube at the inboard end. otherwise it is optional and the connection tube can be blanked off. Check this with PYI.


Since 2014 the amount of compression on the bellows specified was increased to 1.75" for a one inch shaft. There is a chart to figure out correct installation.

Sorry, but I don't think that is correct. There has to be a breather function at the seal assembly so that water can flow up the shaft log and into the seal, and that's only on small vessels. PYI specifies when water must be pumped into the seal assembly on larger vessels. At no time can the seal run dry.

[Bundyon]

I have little experience on Dripless seals but was thrown into the deep end with my current boat. " Mystic " came fitted with a Pommy made DSS, ( ManeCraft) of unknown vintage.
The boat had been sitting in a Marina for a decade or so, then on the Hard for 3 years before I purchased her. I carried out an intensve refit but did not pull the shaft. The prop was extremely hard to turn by hand ( yes, the box was in neutral!!) A mate who is familiar with DSS said it will be fine once it goes in the water!?!
We were splashed almost two weeks ago, water poured out of the bellows, not a flood, but a steady ingress. There was plenty of green corrosion around the outside of the seal. Almost immediately before being splashed, I received a phone call from another mate at the Marina saying some old fella remembered my boat from the previous owner (deceased) saying that the Cutlass Brg would squeal after a short period of time once running?! Too late, I was in the slings of the TravelLift. No Cutlass Brg with a DSS?! Anyway I pulled the Bellows back, burped the seal, and poured boiling water over the corrosion and scrubbed it with a toilet brush! I pulled the hose connection off the water injection nozzle and discovered it was blocked with crap, I ran a drill bit up the nozzle, checked for water flow & reassembled it. At the bottom of the rubber pipe attached to the Donut?/seal was a pinhole leak. I wrapped emergency tape around it and refitted the hose clamp, no more leaks. I ran up the engine with the box in gear, boat tied to wharf, the ingress of water became nothing more than a drip. We then proceeded out into the Harbour, carried out various manouvers and checks over about two hours before berthing in the Marina. No more leaks nor was their any squealing from the seal. I believe the problem is fixed and hopefully we will be trouble free from here on.

[Siberian Sea]

I’m sure there are more then a few who would never haver the older style stuffing box and without doubt their reasons are good but...... my vote is for the stuffing box. Really it’s very simple and all you need to do is just replace the packing rings each few years and that cost almost nothing and is easy. When leaving the boat in the water for longer term storage I just tighten the compression ring a bit and it never drips then back it off some when your going to use the vessel. When in use mine drips about 4 times each minute. Don’t use Teflon packing material unless the manufacturer recommended.

[a64pilot]

Originally Posted by Siberian Sea

Don’t use Teflon packing material unless the manufacturer recommended.

What manufacturer, and why?
Is there some kind of difference in prop shafts from one boat manufacturer and the next?

[mvweebles]

After 25-years, I'm going from a traditional stuffing box to a PSS. I totally understand the arguments for a traditional stuffing box, and I've used most of the modern materials. I seem to be constantly checking and sooner or later, even with a Tupperware container as a sump, my dream of a desiccated dry bilge is history.

I know the argument about catastrophic failure potential against PSS. I've even seen one and it was breathtaking to see how much water came in. The source was an the set screw on the pressure ring had backed off, likely due to improper installation. 5-mins later we were underway.

Of all the fretting about PSS failures, it's the only one I ha e first hand knowledge of. With all the proselytizing of simplicity and effectiveness of traditional stuffing boxes, the vast majority I've see are not adjusted properly. Can it be done? Sure. I've done it dozens of times. Will it stay that way without regular tweaking? Absolutely not. And oh-by-the-way, I have seen one traditional stuffing box fail, though not catastrophically - the bronze threads eventually dissolved. And I have seen a few scored shafts from improperly maintained studding boxes. That's a non-issue with PSS

I have no serious quarrel with traditional stuffing boxes. But they are far from perfect. Count me in the PSS camp these days.