Hemp stern gland seal, comments from the hive please

[aardvarkash10 960]

Leaking profusely.  Steady dribble into the bilge under all conditions except stationary. Tried tightening it, no significant change.

Pulled it off today.  I have no idea what it should look like, so experienced viewers are welcome to comment.

Shaft looks fine.  No grooves or obvious wear.

[John B 106]

Does it have a grease cup, most NZ units do. I first gimmicked up a small grease gun to make a remote greaser  a couple of feet up and nearer to hand, but later bought a specific device from Henleys to do that job. Ie a 1/4 or 1/2 turn as required or on leaving the boat.

[aardvarkash10 960]

16 minutes ago, John B said:

Does it have a grease cup, ...

Yeah, a very nice old brass item, but a 1/4 turn goes nowhere and it still bleeds saltwater furiously...

[K4309 258]

If you feel like spending boat dollars, and have a little space, you can retrofit a dripless shaft seal. We did this after years of tolerating our packing gland dribbling and carrying on. Haven't looked back.

We got one from Henleys. Was in the order of $600 / $700 about 5 years ago.

Alternatively, you can re-pack the stuffing and connected a grease gun to it. I'd give the grease gun a pump or two every time we'd been out. I was super smart and put two connecting hoses onto the grease gun, so I didn't have to crawl to the far end of the bilge to get at it.

Noting that packing glands will always dribble a bit. It is just how they work. If you want a dry bilge you have to part with the boat dollars for the dripless seal.

[aardvarkash10 960]

Thanks K.  I'm not inclined to double the value of SO by lashing out on dripless seals, so I will be rebuilding this system.  If it was just a bit I'd be ok but it's about a litre an hour of run time and slowly getting worse.

[harrytom 643]

best $500 i ever spent 

http://www.chatfieldmarine.com/shop/Driveline/Shaft+Seals/Blue+Water+Shaft+Seal+-+Standard+Model.html

if you are sticking with hemp,need 3 pieces with joins turned from each other,,grease is your friend, I fitted a pressure grease tube to gland in a salthouse 26ft,never leaked

[Psyche 633]

Repack and grease, this type of seal  is pretty simple and have been keeping the water out since forever.

If you were contemplating a change, the  Volvo dripless seals are cheap and pretty good. On the dripless front there are 2 types, one is the rotary face type where one of the faces presses against and rotates on the stationary side, and the other type which uses a lip seal on the shaft. Standard lip seals are not recommended but there is a nitrile type that has a broader flatter lip made by James Walker which doesnt wear the shaft as much. Chatfields make the bluewater models, but youll need to raid the piggy bank!

[K4309 258]

3 hours ago, aardvarkash10 said:

Thanks K.  I'm not inclined to double the value of SO by lashing out on dripless seals, so I will be rebuilding this system.  If it was just a bit I'd be ok but it's about a litre an hour of run time and slowly getting worse.

As P said, I'd just repack and lots of grease. Since you have the shaft out and your own the hard, re-packing is super easy. I have an idea the replacement hemp stuff is only something like $20.

In my view, you can't have too much grease. If you over-pump it, it just comes oozing out, hardly a major issue. You can over tighten them of course, but you can't really over pump it. I used a regular grease gun so I could just drop a cartridge in it. None of this trying to scoop grease into your little 1/4 turn thingee thing. If you are trying to scoop grease into the thingee thing, you could be getting air pockets, which may explain the excessive dripping. It could possibly be that you need to tighten the gland up a bit too. It is a tricky balance not getting it too tight, but tight enough to not drip too much.

[180S 20]

Picture appears to show 3 hemp rings. But they are very dry.

I have tried various packings PTFE , graphite etc but came back to using hemp as it seems to do the job better with no overheating . 

Chatfield marine 124 Sunnybrae Road, Hillcrest, Auckland 0627 sell a length of very greasy hemp which you cut rings (usually 4) and repack. 

[Frank 157]

16 hours ago, K4309 said:

If you feel like spending boat dollars, and have a little space, you can retrofit a dripless shaft seal. We did this after years of tolerating our packing gland dribbling and carrying on. Haven't looked back.

We got one from Henleys. Was in the order of $600 / $700 about 5 years ago.

Alternatively, you can re-pack the stuffing and connected a grease gun to it. I'd give the grease gun a pump or two every time we'd been out. I was super smart and put two connecting hoses onto the grease gun, so I didn't have to crawl to the far end of the bilge to get at it.

Noting that packing glands will always dribble a bit. It is just how they work. If you want a dry bilge you have to part with the boat dollars for the dripless seal.

My experience exactly and the replacement lip seal unit leaked even worse , finally solved with a sail drive  

[K4309 258]

1 hour ago, Frank said:

My experience exactly and the replacement lip seal unit leaked even worse , finally solved with a sail drive  

Crikey.

What brand lip seal did you go with? Was your shaft in good condition? We put a new shaft in at the same time as the dripless seal. There was a bit of necking on the old shaft. I suspect that would have made it difficult for a lip seal to sit down properly.

We did have to put a water pump onto it to provide cooling water. It was thought we wouldn't need to but the temp alarm went off after a long motor one day. Very strait forward putting a water pump on, no issues there, but it was another job and another item to keep an eye on in the future.

[John B 106]

On 3/12/2023 at 3:56 PM, aardvarkash10 said:

Yeah, a very nice old brass item, but a 1/4 turn goes nowhere and it still bleeds saltwater furiously...

Its dry and needs grease( as the photo indicates and others have said), either persevere with the cup or remove the cup and replace with a zerk/grease nipple, get a small grease gun with a flex pipe that gets it nearer where you can reach and  pump it up. Next step , hose clamp the gun to something like a bulkhead or inside a locker and leave it there. Thats a remote greaser. 30 dollar solution.

Or by a Henleys remote greaser ( do they still make em?) you won't regret the investment.

I don't believe that lip seals shaft seals should be retrofitted to old installations unless the propshaft is honed /inspected  /made perfect. Ideal for a new installation. A bellows seal which relies on compression of carbon to metal like John Crane or ( forget the other brand... PSS?) means the shaft condition is irrelevant, so they're ideal for retrofitting to older units.

[aardvarkash10 960]

1 hour ago, John B said:

Its dry and needs grease

Photo is after I'd wiped it clean.  It has had about 500g of grease in the last 20 hours of running - there is no shortage of grease!

Blackwood Engineering had the packing, so I am going to learn how to repack the seals this evening with a chopping board and a sharp razor blade.

[alibaba 77]

If you can, make the ends of the packing where they meet at 45 degrees rather than 90, for an even better seal.

I had the same problem on my old Davidson 28, and replaced with a [relatively ] cheap Volvo seal. Doesn't need much clearance,

and it worked like a charm for years.

[Frank 157]

On 4/12/2023 at 10:25 AM, K4309 said:

Crikey.

What brand lip seal did you go with? Was your shaft in good condition? We put a new shaft in at the same time as the dripless seal. There was a bit of necking on the old shaft. I suspect that would have made it difficult for a lip seal to sit down properly.

We did have to put a water pump onto it to provide cooling water. It was thought we wouldn't need to but the temp alarm went off after a long motor one day. Very strait forward putting a water pump on, no issues there, but it was another job and another item to keep an eye on in the future.

It was  back in the 90's and I cant remember if it was a Henleys or  Chatfield unit but it was attached with the usual  hose and clamps. It think it had a grease cup but not the water feed. I found it leaked annoyingly from  day one despite adding the water feed tube shortly thereafter and the leakage rate deteriorated with use. There is a Finnish sailor on You Tube who installed a similar arrangement during a refit on the US east coast prior to a passage to Alaska. His looked to be beautifully engineered (Blue Water Seal ?)  but also leaked and If I recall he changed it out for a PSS type in Port Astoria. My original BUKH 10 engine-shaft-propellor (2 blade non geared folder)  set up was close coupled and there was always some degree of orbital  movement at the gland so my theory was that the seal was intolerant of this despite the hose attachment. The motor was tired and eventually would not start so I ripped out the entire installation and put a sail drive in, best move I ever made period !  I am a fan of the PSS seal though as there is one on another boat I'm involved with and it hasn't leaked a drop in seven years of ownership and 1500 hours of motoring its 100% tolerant of any shaft movement too !

Edit: The shaft had a groove from the admiralty gland unit but I was careful to ensure the seal was not impinging on that. I think the water feed came from the pressure side of the raw water pump but I'm not 100% sure. When watching the video episode mentioned above there was some footage of the leaking gland and the shaft rotation looked to be rock solid  i.e no axial displacement however I don't know if it was a new shaft from the refit.

[aardvarkash10 960]

Ok, turns out Blackwood's carry gland packing and it comes in standard engineering dollar pricing, not boat dollars.  You even get your work discount.

I did find it on AliExpress at about 20% of the NZ retail price, but the 20 day delivery made it unworkable.

 

[ex Elly 197]

Also AES (Auckland Engineering Supplies) at Westhaven sell it. They can cut you off a length.

 

[aardvarkash10 960]

OK, cut now and fitted to the housing.  The three new rings are significantly thicker than the old ones that came out and there are only three threads visible on the housing - there was at least 6 with the old rings.

I'm taking this as a Good Sign.    

[aardvarkash10 960]

....and its back together.

I'm glad we waited to do it hauled out.  The gland housing had three packing rings in it and we replaced them like for like.  However, the new packing takes up more space - it hasn't compressed over time like the old packing.  On top of this, there was very little space between the rear of the gearbox and the shaft log.  

Consequently, the shaft had to be pulled sternward to allow the gland housing to be threaded back onto the log.  I then had to "encourage" the shaft back into the housing with a block of wood and a 20 oz "Gentle Persuader".

Once in place the shaft turns nicely, everything lines up and the gland housing has two turns onto the log with another six to eight turns available as the seal wears.

Not in the water yet, but I'm quietly confident that the job was done.  Thanks everyone for the encouragement and advice

[SanFran 12]

Hi Ashton.  Sounds exactly what I did a few years back on SF.  New seals were thicker and I only got 2 on, but working fine.  No drips. Very careful not to strip threads too.  Wire brush the threads and grease.  Catch you up out there.