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Jiggz
05-24-2014, 02:47 AM
Greetings from West Africa!Back home in Cape Town we are busy with the refurbishing of an old lifeboats, fibreglass-built by Lambie in the U.K. in the very early 1980's.Extraction of the propeller and shaft revealed a beautifully made bronze stern tube assembly, filled with very old, very black, very hard old grease.And nothing else.....The bronze cast/machined piece that screws onto the outboard end of the tube carries within it a shallow groove that really looks as if it takes something like a seal or "O"-ring, the propeller shaft has as band of brightness on its circumference in way of where this groove would be on reassembly; but I am assured by the man who dismantled and cleaned the stern tube that nothing other than old hard grease came out......Does anyone have any experience/knowledge of the best/correct way forward with this?I do have images of the relevant bits, but am having difficulty resizing and uploading them on a tablet aboard a vessel about 50 miles off the coast of Abidjan, Cote d'Ivoire.......It seems I can email them however.Any advice or suggestions would be much appreciated.

willmarsh3
05-24-2014, 05:35 AM
The best way with the pictures is to put them on a photo sharing website like photobucket or flickr. Make sure the images are shared publicly. Post the links to the images here.

Much more detailed instructions are here: http://forum.woodenboat.com/showthread.php?121390-Thorne-s-new-and-improved-quot-how-to-post-photos-quot-instructions

BTW welcome to the forum. Others will be along shortly with help about the prop shaft.

Breakaway
05-24-2014, 09:55 AM
Typically--or at least fairly common-- you'd have a bearing inside. captured between washers and held in place by a snap ring.

Kevin

shade of knucklehead
05-24-2014, 10:09 AM
Pics will help.

we machine a groove in our stern bearings on the outside and install o-rings where it connects to the shaft tube. Could that be what you are talking about? The shaft itself should only be shiny where the actual cutlass bearing rubs, otherwise there is a problem

Thorne
05-24-2014, 10:44 AM
Here's how to post photos on this forum:


FIRST - Don't attach photos. Only a tiny version will display.


SECOND - Post the photos on the web. Use your own website or a free image hosting service like www.flickr.com (http://www.flickr.com/), picasaweb.google.com, picturetrail, photobucket, etc. Images posted on Facebook must be set to "Public" access via the Edit option, not limited to "Friends".


THIRD - Once posted on the web, right-click the photo to "Copy Image Location", or drag the photo to another browser window, then copy the image URL (web address) which will end in ".jpg". You can test by pasting the photo URL into the location field (http://* ) of a web browser and see if the photo displays. Remember that this process will not work for photos located just on your computer, on members-only Yahoo groups, or on Facebook unless set to "Public" view.


In Flickr - First click the photo to bring up the options on the right, click the " ... " (More) link, in the next window click "Download / All Sizes", then in the next window click "View All Sizes" near the bottom right. Then you can get the image URL by right-clicking the image.


FOURTH - DO THIS EVERY TIME TO POST IMAGES IN THREADS:
A. In any "Reply" window you can click the "insert image" icon --> a little yellow square icon with a dot at each corner, a tiny tree in the center.


Depending on browser version and Reply/Edit status, this may bring up a simple window with a field to paste the URL into, or the "Add an Image" window described below.


B. If the window titled "Add an Image" comes up, click the "From URL" tab, paste the URL of the photo in the field, deselect the box for "Retrieve remote file and reference locally", then click the "INSERT IMAGE" button. The Forum software will resize some large images, so look at your post to see the actual displayed images.


NOTE - most common problems are due to missing the step described above -> deselect the box for "Retrieve remote file and reference locally"

Jiggz
05-27-2014, 02:23 PM
http://i268.photobucket.com/albums/jj29/wallacehartley/20140520_141003_zpske1vttaa.jpghttp://i268.photobucket.com/albums/jj29/wallacehartley/20140520_141012-1_zpsmaut6qlg.jpghttp://i268.photobucket.com/albums/jj29/wallacehartley/20140520_141023_zpsqfvcnrvv.jpg
The best way with the pictures is to put them on a photo sharing website like photobucket or flickr. Make sure the images are shared publicly. Post the links to the images here.

Much more detailed instructions are here: http://forum.woodenboat.com/showthread.php?121390-Thorne-s-new-and-improved-quot-how-to-post-photos-quot-instructions

BTW welcome to the forum. Others will be along shortly with help about the prop shaft.

Jiggz
05-27-2014, 02:26 PM
http://i268.photobucket.com/albums/jj29/wallacehartley/20140520_141139_zpswy4flkp4.jpg

Jiggz
05-27-2014, 02:28 PM
http://i268.photobucket.com/albums/jj29/wallacehartley/20140520_141045_zpsivmerovv.jpg

Jiggz
05-27-2014, 02:32 PM
Thanks for the pointers, guys.
Uploading to photo bucket proved challenging from out here, comms are a bit sketchy!

I hope the images help.
There was no bearing nor a discernible seal at the open end of the tube, but something wore a bright ring on the propeller shaft!

Thad
05-27-2014, 04:02 PM
Out of my experience. You say the tube was filled with grease. The groove does look like it is made for an o ring. I would expect some kind of dripless bearing/seal clamped to the inboard end with a grease fitting. Someone should come along with experience with those things. My experience is with a similar set up, but with a larger aft casting made to carry a cutlass bearing, water lubricated, with a stuffing box attached to the inboard end, also water lubricated.

jackster
05-27-2014, 04:32 PM
Jiggz,
Nice job with the pictures.
I am assuming that this lifeboat is a powerboat, not converted to sail.
For a powerboat, that system with an O-ring (if, indeed that is what the groove is for) leaves a lot to be desired.
Especially for frequent and/or continuous use. IMHO. (Maybe why there was no trace of an O-ring and why it was packed with old, hard grease!!)
A better approach is with a cutless bearing, as Kevin and Bryan (shade of knucklehead) say.
Is there a packing gland on the inside?
Might be as easy as machining the fitting larger for the cutless bearing, (Or not!! :) )
Best of luck with your project.

shade of knucklehead
05-27-2014, 04:53 PM
What is the shaft size? What is the inside diameter of the bearing area? I have seen setups like this where the cutlass bearing has completely worn off until there is only the metal portion left. If you remove the bearing from the tube can you press out the inner piece?

Jiggz
06-04-2014, 06:09 AM
Hello all, returned from West Africa and home in Cape Town this time!

I really appreciate all the feedback, guys.

Being a ships lifeboat it is purely motor powered, intended to be run out of the water fairly frequently, and not intended to be run in the water for very long at all!
That hardly makes sense, but that is the reality of the life of a lifeboat!

There were no metal bits that came out of the tube at all, no bearing, no seal.....just a quantity of what appeared to be old hard, black grease that was scraped out rather than wiped out with a rag.

On the inboard end is indeed a greaser arrangement, and I will investigate myself if there is a seal of some sort on the inboard end of that.
The shaft itself is about three feet long and initial impressions of viewing it myself are that the casting at the end of the tube is itself the bearing, that nothing else is pressed into it. Reasons for thinking this are that the internal diameter of the casting is very close to the external diameter of the shaft, give or take some wear, and that an end-on view of the casting reveals a slightly ovoid shape to the bore, worn out-of-round at the bottom and slightly to the seven o'clock position - as one would expect to see from a heavy prop on a heavy shaft running in one direction for far longer than the other.....

I will take more images tomorrow and take some measurements too, and post them, and see if we can reach a concensus.

I think the casting can be machined and sleeved to take up the wear and that between the bronze casting and the inboard greaser, pending the finding of some sort of sealing arrangement inboard of that.......that's the way it possibly works.

I'll post more tomorrow.....

slug
06-04-2014, 06:17 AM
The outboard end needs some kinda cutlass bearing and the inboard end...the waterproof end...will have some kinda packing, a clamping arrangement and a grease nipple.

I can see somekinda bearing material on the inside of the bronze casting pictured. What is this material.

sdowney717
06-04-2014, 07:47 AM
It is a lifeboat.
The shaft arrangement is meant for limited short time use.
Motors and maintenance would be tested-run out of the water? So water cooled bushings are no good, hence the grease and seal.

Shiny spot on the shaft, likely was a rubber seal loose fit oring or square ring rubber, maybe even some kind of fiber packing to aid keeping in that thick grease.
Just a guess. It does look like the bronze part could have had a seal pounded in. You can get rubber coated seals.
A slow turning shaft can use a thick heavy grease.

If this is to be used a lot. maybe redo with different parts using a standard water bearing design.
Otherwise you need a seal and pump grease in after some hourly schedule of usage.
Would pumping in grease cause a seal to pop off? Maybe I dont know. Lots of unknowns.

On my standard water design with hull bolted strut I went with a plastic vesconite bushing which they machine to size. The company is in South Africa.
http://www.vesconite.com/
Much cheaper and better for me.

jackster
06-04-2014, 08:02 AM
Being a ships lifeboat it is purely motor powered, intended to be run out of the water fairly frequently, and not intended to be run in the water for very long at all!
That hardly makes sense, but that is the reality of the life of a lifeboat!

So, do I understand correctly that this will CONTINUE to be a lifeboat? Used to save people endangered in the water!? For rescue purposes!?
If so, I would want the shaft and driveline to be engineered for the purpose. By an engineer. Maybe a sealed bearing arrangement designed for dry running.

How is the engine cooled? Obviously it does not rely on any raw water.