Reply
 
Thread Tools Display Modes
 
Old 03-16-2014, 06:33 PM   #21
Enigma
 
RT Firefly's Avatar
 
City: Slicker?
Country: Bumpkin?
Join Date: Oct 2007
Posts: 9,994
Greetings,
Packing material too tight. Remove all and re-pack properly. My $.02.
__________________
Advertisement

__________________
RTF
RT Firefly is offline   Reply With Quote
Old 03-16-2014, 06:48 PM   #22
Guru
 
Ski in NC's Avatar
 
City: Wilmington, NC
Country: USA
Vessel Name: Louisa
Vessel Model: Custom Built 38
Join Date: Jan 2014
Posts: 3,879
Quote:
Originally Posted by N4061 View Post
Base upon my schematic what or where would you conclude is the problem? Thanks
My best guess is the packing was installed too tight, or not allowed to break in. That causes gland to run hot and not drip. They took out 50% of the packing and water still did not come out. That is because 50% of the packing is still in there, and apparently is still sealing. So take that packing out too, and you should get flow.

Next, put packing in loose, and let it dribble. With shaft rolling, gradually tighten until drip slows. If shaft gets hot, put in neut and let it cool, repeat. Not uncommon for gland to get hot with new packing. It needs to be carefully adjusted and allowed to break in.

See my earlier post that described my experience.
__________________

Ski in NC is offline   Reply With Quote
Old 03-16-2014, 07:08 PM   #23
Guru
 
Join Date: Feb 2010
Posts: 655
Nordhavn Input

Quote:
Originally Posted by magicbus View Post
An excellent idea.

Dave
I spoke with Dan (co-owner) of PAE Nordhavn (they know us well) and he was not sure himself what could be causing the problem. We are using one of the best yards in San Diego (well respected for over 60 years) and they handle Nordhavns from time to time but this is not a Nordhavn specific problem. Based on original owners input, the box always showed in 100's (not sure how high) which is leading me to think this may have been an issue from day one and he never realized it. It may have become worse after he had it repacked since the older packing material was well worn out. This wouldn't be the first time in history that something went unnoticed for many years by the owner then when the boat or car changes owners it is noticed.

I'm still waiting to hear from everyone what temperatures you register off the coupling at cruise speed with this type of stuffing box? Thanks
N4061 is offline   Reply With Quote
Old 03-16-2014, 07:23 PM   #24
Senior Member
 
City: Green Cove Springs, Florida
Country: USA
Join Date: Feb 2012
Posts: 208
Send a message via Skype™ to bglad
To answer your question specifically I don't recall seeing packing glands running much more than ambient water temperature. That is a gland that has been run in.

One thing I do not see on your diagram is a cooling water line. Many (in fact most) glands I see have those. They are usually taken from the main engine raw water cooling system somewhere. Possibly you are missing yours or it is clogged? If you don't have one that could be your problem. If you do then it may not be flowing properly due to a clog somewhere.

I have attached a picture of one in a 44' DeFever I recently surveyed. The cooling line is the copper tubing. The wire is for bonding the fitting.

Good on you for your persistence in resolving this although I don't think the stainless, bronze or flax cares much about 100 degrees F. That being said it is a substantial difference if you are starting with 50 degree F water...

Quote:
Originally Posted by N4061 View Post
I spoke with Dan (co-owner) of PAE Nordhavn (they know us well) and he was not sure himself what could be causing the problem. We are using one of the best yards in San Diego (well respected for over 60 years) and they handle Nordhavns from time to time but this is not a Nordhavn specific problem. Based on original owners input, the box always showed in 100's (not sure how high) which is leading me to think this may have been an issue from day one and he never realized it. It may have become worse after he had it repacked since the older packing material was well worn out. This wouldn't be the first time in history that something went unnoticed for many years by the owner then when the boat or car changes owners it is noticed.

I'm still waiting to hear from everyone what temperatures you register off the coupling at cruise speed with this type of stuffing box? Thanks
Attached Thumbnails
Click image for larger version

Name:	DSC09756.jpg
Views:	212
Size:	163.1 KB
ID:	28341  
bglad is offline   Reply With Quote
Old 03-16-2014, 07:25 PM   #25
Guru
 
Northern Spy's Avatar
 
City: Powell River, BC
Country: Canada
Vessel Name: Northern Spy
Vessel Model: Nordic Tug 26
Join Date: Feb 2012
Posts: 2,665
Hmmm. I'm still waiting for the PDF. Must be because I'm on a phone. Will look at it when I get near a computer.
Northern Spy is offline   Reply With Quote
Old 03-16-2014, 08:07 PM   #26
Guru
 
twistedtree's Avatar
 
City: Gloucester, MA
Country: USA
Join Date: Jan 2013
Posts: 3,174
I've got exactly zero experience with packing glands like this, but I'll venture a theory anyway.

I think you are starting out with the packing too tight. Entrapped air is preventing the tube and glad from ever fully flooding which would explain why there has been no sign of sea growth up there. With no water there is no lubrication and things run hot. It's probably been this way since day one.

Question: The previous owner said the temp was always 100ish. Was he ever getting drips out of the seal, or was it always dry?

As a starter, I'd start with the packing VERY loose and encourage active water flow initially to ensure the tube is completely flooded and bled of air. Then tighten just enough to control the water flow, but keep it going at a higher than normal rate for some initial break-in time. Monitor the temp to see if it's now closer to sea temp. Assuming it is, then over time tighten up to whatever drip rate you want.

After all that, if the temp does back up then I'd guess that air is getting back in there an/or you have too little water circulation. Creating more clearance may help, but if the problem it air introduction an entrapment, then I don't think more clearance will solve the problem. I'd then start thinking about a vent line like in the Defever picture to allow the air to self-bleed. If that doesn't work then you could consider using the vent line to actively flush water from the packing gland back out through the shaft tube. This is commonly done on higher speed boats to get enough water flow.
__________________
www.MVTanglewood.com
twistedtree is offline   Reply With Quote
Old 03-16-2014, 08:12 PM   #27
Guru
 
Join Date: Feb 2010
Posts: 655
Quote:
Originally Posted by bglad View Post
To answer your question specifically I don't recall seeing packing glands running much more than ambient water temperature. That is a gland that has been run in.

Thank you for your post. My N40's and this boat do not have an extra cooling line as shown in your picture. I plan to watch the technican remove all the packing and see what happens. If we are still not getting water then I have to conclude something else is fitting too tight. Fortunately the shaft is fine and no damage anywhere but this is a strange one to figure out. Especially the owner reports low 100' as remembered temperatures, that's just a little warm for me. I know most people wouldn't stress as much as I am but I am a little of a perfectionist when it comes to boats. Not a good sickness to have but has made for safe boating over the years!

john
N4061 is offline   Reply With Quote
Old 03-16-2014, 09:53 PM   #28
Guru
 
Northern Spy's Avatar
 
City: Powell River, BC
Country: Canada
Vessel Name: Northern Spy
Vessel Model: Nordic Tug 26
Join Date: Feb 2012
Posts: 2,665
First of all, this is nearly the easiest application for packing. The shaft speed is low. SAY 1.5 inch shaft turning at 1500 rpm is only 589 fpm (relatively slow). The medium is clean cool water. The differential pressure is low. There is not much axial play. There is little radial movement. This is not rocket science.

Lets start with terminology because I'm still a bit confused. The fibreglass housing is typically called the stern tube. What you are calling a coupling is commonly called the stuffing box, packing box, or packing gland. The shaft goes through it and it provides an annular cavity in which the the packing goes into. The piece that is you adjust the packing compression with the two nuts on the studs is called the packing follower or the gland follower.

Do you have a large diameter hose between the stuffing box and the stern tube? Or is the stuffing box rigidly mounted to the hull? The reason I ask is that the packing boxes with a chunk of hose are (somewhat) self-aligning.

Personally, I'd do as the others said and pull out the packing and replace. It may have been packed incorrectly (particularly when you say they cut a half in off or so) and needs a burp. I'm a big fan of GFO packing. It should last many, many years in a boat. I've used in in 4" shafted 1,800 rpm continuously running pumps for years.

A good tutorial can be found here. There are lots of other out there.

I won't repeat what others have said, but here are a few other things you may consider.

Is the packing gland cocked? Measure the flange ears to stuffing box distance on both sides.

Is the packing the right size? It should go in rather easily.

Misalignment. You had the cutlass bearing changed. Is the new one straight? Was the old one worn? When you have the packing out, you can measure the concentricity of the shaft in the stuffing box.

100F is nothing to a box like that. Once it wears in a bit it will run cool down.
Northern Spy is offline   Reply With Quote
Old 03-16-2014, 09:54 PM   #29
TF Site Team
 
Peter B's Avatar
 
City: Brisbane
Country: Australia
Vessel Name: Lotus
Vessel Model: Clipper (CHB) 34 Sedan/Europa style
Join Date: Jun 2008
Posts: 6,668
Send a message via Skype™ to Peter B
I think the thing to keep in mind here, John, bearing in mind your perfectionistic tendency, (which I share, and often have to discipline myself over, especially when it relates to boats), is this is just a stuffing box. Stuffing boxes are rude, crude, but frightfully effective, and through a range of conditions. I think you are lucky yours does not rely on forced cooling, (nor does mine), as these types never suddenly completely fail, and as I posted before, is often dripless when not turning after a new pack, but still runs quite cool, and 100F is less than 50C, so just tolerable hand hot, and not really a worry, as Northern Spy said. If water is getting up to the packing coupling that's really all that matters. The small drip one often sees is certainly not enough flow to create meaningful circulation, just one small sign it is there. Keeping tabs on the temp for a bit will do that. Rotation of he shaft should ensure a movement of water around and back down the shaft just by differential expansion. But a check the repack was not too over-tight, as others have mentioned, and that the packing follower is square to the box, does make sense. This should be at no further charge to you in my opinion also.
__________________
Pete
Peter B is offline   Reply With Quote
Old 03-17-2014, 09:24 AM   #30
Guru
 
Aquabelle's Avatar
 
City: sydney
Country: australia
Vessel Name: Aquabelle
Vessel Model: Ocean Alexander Flushdeck
Join Date: Jun 2012
Posts: 537
I would conclude the schematic is wrong...never seen or read about an arrangement like that.
Aquabelle is offline   Reply With Quote
Old 03-17-2014, 01:04 PM   #31
THD
Guru
 
City: Seattle
Country: US
Join Date: Apr 2012
Posts: 1,142
I have to agree with Aquabelle. The drawing shows the "coupling" to have sort of a nipple shape at the junction with the stuffing box. Hard to see how the flange at the other end of the coupling can serve to compress the packing in that arrangement.

That said, several questions some to mind. It seems the diagnosis at this point is that there is come point where the shaft and tube have insufficient clearance to allow water to enter. From the drawing, hard to visualize where that might be. Normally, the only point at which the shaft is in near contact with the shaft is at the front of the adjusting nut. From your drawing it appears that you have an adjusting flange rather than an adjusting nut.

1. Is there water between the cutlass bearings? If all packing is removed, is there free flow of water at the collar (coupling?). It sounds like you have free water flow up to the stuffing box and none past that point. That would seem normal to me (other than the requisite desired "drip").
THD is offline   Reply With Quote
Old 03-17-2014, 03:00 PM   #32
Guru
 
psneeld's Avatar
 
City: Avalon, NJ
Country: USA
Vessel Name: Freedom
Vessel Model: Albin 40
Join Date: Oct 2011
Posts: 15,853
With the new packing materials...there is no "requisite" drip any more...often it will just look moist/ooze and stay cool...thus my reason to not have a burning desire for a "modern dripless" box.

Funny there's no injection unless the fiberglass shaft tube on the boat is pretty short...often the injection is as much about supplying oxygenated water to the shaft packing area to keep the shaft from corroding.
psneeld is offline   Reply With Quote
Old 03-17-2014, 05:58 PM   #33
Guru
 
twistedtree's Avatar
 
City: Gloucester, MA
Country: USA
Join Date: Jan 2013
Posts: 3,174
Quote:
Originally Posted by psneeld View Post
Funny there's no injection unless the fiberglass shaft tube on the boat is pretty short...often the injection is as much about supplying oxygenated water to the shaft packing area to keep the shaft from corroding.
I've heard that is also depends on the boat's speed. A faster boat creates more of a venturi effect and tries to draw water out of the shaft tube rather than let it flow in and circulate around. With the faster speed trying to draw water out, injecting water in at the stuffing box works with the venturi process rather than against it.

I believe John's boat is a semi-planing hull, and perhaps the first such hull that Nordhavn designed. Perhaps it's boarder-line between the two worlds of displacement boats with natural water circulation up to the stuffing box, vs planing hulls with water flushing fore to aft through the box and down the tube.
__________________
www.MVTanglewood.com
twistedtree is offline   Reply With Quote
Old 03-17-2014, 06:20 PM   #34
Guru
 
psneeld's Avatar
 
City: Avalon, NJ
Country: USA
Vessel Name: Freedom
Vessel Model: Albin 40
Join Date: Oct 2011
Posts: 15,853
what I'm talking about has nothing to do with keeping water in the tube because of boat speed... it's abut stagnant water in there harming the stainless....I've heard but not have seen that some manufacturers are plumbing a/c pumps to them to keep the water in there oxygenated.
psneeld is offline   Reply With Quote
Old 03-19-2014, 08:57 PM   #35
Guru
 
Join Date: Feb 2010
Posts: 655
We found the problem (we hope)

Sometimes its the last place you look to find the gremlins! After a wonderful five days of sitting in the yard (weekend included) I finally picked up La Tempestad and took her home. I got the feeling we had abandon her when I checked on her Monday sitting in a corner, getting dirty and looking depressed (can a boat look depressed? OK, maybe I was the one depressed). During this visit the crew showed me the bronze compression plate and gland pieces which were in the back shop. With a pair of calibers they measured the inside fit (after cleaning up the corrosion build-up) and we only had .007 clearance. A call to the factory conformed the tolerance is .015 - .020. So, the combination of an out of spec fit along with corrosion build-up resulted in no water flow. This theory was previously confirmed when the crew removed all the packing and could not get any water to flow forward. After the compression plate was machined down and everything was cleaned up the boat was put back in the water without packing to confirm water flow. Packing was then installed and a short test run showed water dripping by the crew.
When I arrived yesterday afternoon the lead technician and I took the boat out for a test run and confirmed water dripping and temperatures were not climbing as fast. I paid the bill (north of $3K) set off into the sunset. OK, maybe not the sunset but did take the boat home. I made one check along the way and temperature was in the 90' with a little dripping. After reaching my slip I did one more check and temperature was 104 degrees compared to 119 degrees when I took the boat to the yard. Water was dripping strong and I think we may have found the fix. I realize I will need to let the packing set in and may run a little warm for awhile but "we have water flow". Owning a boat definitely offers you the opportunity to learn something new every day. Now I hope this journey is over so we can start to really enjoy the boat. I wonder if PAE will cover this 10 year old latent defect if we signed up for N4 (ha ha)?

John T.
La Tempestad
N4061 is offline   Reply With Quote
Old 03-19-2014, 09:55 PM   #36
Enigma
 
RT Firefly's Avatar
 
City: Slicker?
Country: Bumpkin?
Join Date: Oct 2007
Posts: 9,994
Greetings,
Mr. N. Well, I never.....I guess you DO learn something new every day. I stand corrected about my "Don't let them machine a thing" comment. Glad it all worked out in the end. Who would have thunk?
__________________
RTF
RT Firefly is offline   Reply With Quote
Old 03-19-2014, 09:58 PM   #37
Guru
 
psneeld's Avatar
 
City: Avalon, NJ
Country: USA
Vessel Name: Freedom
Vessel Model: Albin 40
Join Date: Oct 2011
Posts: 15,853
Is the stuffing box even made by Nordhavn? Or is it someone elses?

If they get their stuffing boxes from another source, I wonder if they mismatched parts or something...I have never heard of a regular old stuffing box with a similar issue.

Still sounds too strange...
psneeld is offline   Reply With Quote
Old 03-20-2014, 08:07 AM   #38
TF Site Team
 
Peter B's Avatar
 
City: Brisbane
Country: Australia
Vessel Name: Lotus
Vessel Model: Clipper (CHB) 34 Sedan/Europa style
Join Date: Jun 2008
Posts: 6,668
Send a message via Skype™ to Peter B
I agree. They are normally just not about that sort of close tolerance...
__________________
Pete
Peter B is offline   Reply With Quote
Old 03-20-2014, 10:31 PM   #39
Guru
 
Aquabelle's Avatar
 
City: sydney
Country: australia
Vessel Name: Aquabelle
Vessel Model: Ocean Alexander Flushdeck
Join Date: Jun 2012
Posts: 537
BGlad (and anyone else): do you know the brand of the stuffing box shown in your photo at post #24? It looks just like mine, though mine is larger (for a 2 1/4" shaft). I have stainless drip-catch boxes under mine, with a drain line from these to a nearby shower-sump-pump box...so no drips into bilge
Aquabelle is offline   Reply With Quote
Old 03-20-2014, 10:52 PM   #40
Guru
 
Ski in NC's Avatar
 
City: Wilmington, NC
Country: USA
Vessel Name: Louisa
Vessel Model: Custom Built 38
Join Date: Jan 2014
Posts: 3,879
0.007" clearance still should have allowed water flow to packing gland. That is not that tight. Unless clearance was jammed with corrosion.
__________________

Ski in NC is offline   Reply With Quote
Reply

Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off





All times are GMT -5. The time now is 01:08 AM.


Powered by vBulletin® Version 3.8.8 Beta 4
Copyright ©2000 - 2017, vBulletin Solutions, Inc.
Search Engine Optimization by vBSEO 3.6.0
Copyright 2006 - 2012