GFO Follies

[Gulf Comanche]

Started the stuffing box repacking about 9 this morning. 45 minutes or so later, I pulled the last of 6 flax rings out of the nut.The corkscrew worked ok but needed the picks too. Then began the cutting of the GFO rings, huge PIA. Laying on the galley floor hanging over the shaft alley, water flowing in, tryin to get the correct size. One problem was that stuff frays badly, so when it’s finally inside the nut I wasn’t sure if the ends touched or not. Pressed on as there was no other choice and I only had 2 feet of GFO to work with. Got 3 rings into the nut, staggered at 90* or so, and started screwing the nut back on. The nut finally goes all the way to the end of the threads and still big water flow. Back the nut off, the last little bit of GFO was short so I put the one piece of flax I had in the nut and screwed back on. Water finally slows to a few drips and then stops later in the day, flax probably expanded or something. The GoreTex site instructions say no more than 3 rings; I could easily do 5 or 6 because of the depth of the nut. Not sure if the threads inside the nut made the rings turn over and not seat properly or the frayed ends caused the leakage. Have not run the boat yet pending some opinions from TF crew. This job beat the sht outta me.

 

[Comodave]

We will see how it goes when we launch. I rebuilt one of my stuffing boxes, new hose, clamps, new cooling hose and new GFO packing. It had 6 layers of GFO in it previously and had no issues. The PO used GFO and the yard that maintained it put the 6 layers in. So I put 6 new layers in and hand tightened it per instructions. I didn’t have any trouble cutting it but my boat is out of the water. I staggered the cuts 120 degrees. Time will tell when we launch it. Have you run the boat, they say run it 5 to 10 hours before adjusting the box. I have since replaced the bonding wire that was a bit too short.

 

[Gulf Comanche]

Have not run it yet Dave. May run it tomorrow

 

[Comodave]

Yes, don’t have it tight when you break the GFO in. They say not to go more than finger tight for 5 to 10 hours and then tighten it up. It will be a pain for that time having it leak but then it should last just about forever. It was in mine and didn’t leak at all but I wanted to replace the old hose so I had to repack it. If you look closely at the photo you can see where my stuffing box was tightened up to previously by the different coloring of the verdigris. So I have a ways to go on the tightening.

 

[Gulf Comanche]

Does GFO swell up after installation?

 

[High Wire]

For the next time, you can pre-cut the rings on the shaft outside the gland to save time before water is pouring in.
Packing clearance will clog up with particulates in the seawater. Pretty quick if the water is dirty. The clog disappears when the shaft is turned.

 

[Comodave]

Does GFO swell up after installation?

That I don’t know. No clue...

 

[Comodave]

For the next time, you can pre-cut the rings on the shaft outside the gland to save time before water is pouring in.

I cut mine on the shaft between the stuffing box and the coupler but then again mine is out of the water so I wasn’t in any hurry.

 

[Northern Spy]

Does GFO swell up after installation?

No.

 

[Northern Spy]

You put in enough rings to fill the gland. There is no maximum amount, it is determined by the depth of the stuffing box and the length of the gland. The only rings that do any actual sealing are the last two rings. They do 70% of the sealing as the axial force that the gland puts on the packing is not evenly distributed as a radial force. This is why you can use a throat bushing as a spacer in deep stuffing boxes.

So in essence you have flax packing with gfo backing.

Generally speaking it is best to precut the rings on another part of the shaft or a mandrel (chunk of pipe the same diameter). Use a brand new razor and slightly saw it back and forth. It takes a bit of feel to do it well, but you are right, it does fray easily.

 

[Northern Spy]

I knew one millwright who swore by spraying his Olfa knife with silicone before cutting packing.

 

[FF]

Next step is another 3ft to finish the job , cut with a razor to size and shape before entering the hell hole.

 

[C lectric]

Another note from here about cutting ahead of time and using the part of the shaft outside the box as a mandrel. Even better is if you can get a piece of shafting and do them off the shaft.

Razor blades, Olfa knives are almost a must to get a sharp enough edge. Olfa, I break off each use section to work with a new one. I cut them a hair long on the angle.

I also use a piece of pvc or abs pipe as a tamper that has been cut in half or less lengthwise and press carefully and evenly working around to not punch holes in the new packing with a screwdriver.

Even the older packings could be holed with a screwdriver.

Yes, get some more GFO and install another ring but do cutting first.

 

[Comodave]

Yes, I also have a piece of PVC pipe cut lengthwise to push the packing into the log. Works great.