Stuffing box - Hows it connected to stern tube?

[pjsmith]

Hi All,

OK - I'm back in fix the boat mode. Spent yesterday down there and cut a big hole in the deck to get access to the otherwise inaccessible stuffing box. Been searching around the web, but can;t find the answers, so hopefully someone here in this great collective will be able to enlighten me.

Here is my stuffing box, attached to a small bulkhead, behind which is the stern tube (pictured below)





The bolts visible in the stern tube pick are not the other side of the bolts that hold the box in place. It looks like this area was perhaps re-enforced in the past, or during construction and the bolts glassed in from both sides.

I had some broken worn out engine mounts. These shook the shaft and I believe broke these 2 highlighted bolts loose. Both nuts (arrowed), and bolts when you try to turn the nuts rotate in place, so there is no way to tighten them. I assume that stuffing box should be rigidly mounted to the bulkhead? At certain RPM, it can still be seen moving a few mm side to side, though significantly better now the engine mounts are replaced. The nuts are captive, they don't come out the other side of the bulkhead, so despite me now having access, I cannot extract them or tighten them.

Grease - Lots of grease, had come out the other side of the box, behind the bulkhead. I cleaned up handfuls of it.

So, hopefully someone with more knowledge will be able to help me with these questions

How is the box attached to the tube? Is the tube threaded, or is it just a butt fit into the packing box? If grease is escaping the back of the box and the tube is threaded, perhaps it is broken? It does not leak a drop, but if screwed in, how could grease escape?

My plan, dependant on the above, was to cut off the nuts and try to rotate the stuffing box a few degrees (right? - depends on thread, if exists), drill new holes right through bulkhead and secure with new bolts. Align propshaft - job done?

Access is still a pig, but my concern is what happens when I remove those bolts. Presumably, I could pull that box forward up the shaft (and water would come in?)

Many thanks for any further advice. I really miss my boat!

 

[AndyL]

Is the tube threaded, or is it just a butt fit into the packing box?
I would expect it to be threaded, but it looks as if those are studs with nuts holding it on, so it can't be threaded as there's no way to unscrew it?

 

[Lodesman77]

It looks like mine - the bolts hold the fitting to the bulkhead for shaft alignment but the fitting is screwed onto the tube...



May be more/better info at - http://coxeng.co.uk/stern-gear/stern-glands/

 

[pjsmith]

Is the tube threaded, or is it just a butt fit into the packing box?
I would expect it to be threaded, but it looks as if those are studs with nuts holding it on, so it can't be threaded as there's no way to unscrew it?

Good point - I had not thought about that. If studs, as you say, no way to unscrew. My only thought there is that the section has obviously been re-enforced at some point. Maybe when built, but if later, perhaps the owner just glassed over the bolts.

 

[pjsmith]

It looks like mine - the bolts hold the fitting to the bulkhead for shaft alignment but the fitting is screwed onto the tube...

View attachment 70482

May be more/better info at - http://coxeng.co.uk/stern-gear/stern-glands/

Thanks. There is no visible thread, but it may be inside the bulkhead. I see no way for grease to escape the rear of that fitting, save for the idea that it has come lose from the stern tube. I'm tempted to want to unscrew it completely now, but I think I'd better do that out of the water...

 

[Lodesman77]

On mine the fitting holds a white metal bearing, so the fitting needs to be aligned with the shaft. When the bolts in the bulkhead became loose (prop was caught/jammed by a bit of fishing net) the wear on the bearing was significant.

 

[rogerthebodger]

When I purchased my current boat as a hull and engine the stern seal was a conventional stuffing box like yours. The end of the stern tube had a flange welded on to the tube and the stuffing box also had a matching flange so the stern tube and stuffing was bolted together in my case with 4 bolts.

The flange and the stuffing had a matching recess and spigot to ensure alignment. The flange was sealed with a conventional gasket and gasket maker .

I replaced this rigid setup with a PSS seal arrangement with an extension to the stern tube to take the rubber bellows of the PSS seal. This extension was bolted to the flange on the stern tube and sealed with a gasket.

I would not do anything to the gland until the boat is out of the water in case you break anything.

 

[neil_s]

You might have an old fashioned white metal outboard bearing - this is why your stuffing box sends grease down the tube. This might also be why you don't see any water leaking in.