stuffing box packing materials

I bought my boat last year and not long after I started using it, both stuffing boxes started leaking a fewe drops a minute, regularly at rest. The PO never changed the stuffing and the guy he bought the boat from could not recall how long it had been since he had changed it, so I lived with it for the season rather than risk shaft damage by tightening potentially dryish packing.



Once the boat was hauled last Fall, I replaced the stuffing (which was flax and still decent) with a "PTFE/flax-moldable dripless packing-PTFE/flax" sandwich per the Nigel Calder recommendation. The boat is still on blocks and the stuffing boxes are still loose. I will be checking the alignment before I tighten everything up. I'm starting to think my choices in packing material might be a mistake because I have read that the moldable stuff does not work well for planing-hull boats and might get too hot even when adjusted per the manufacturer recommendation. That said, I did the calculations and my prop-shaft diameter and max shaft RPM are within the published limits for the stuff.



I am left with 4 options:


1. Replace the packing material with something else.

2. Adjust the new packing material per the instructions that came with it (no drips ever) and worry all the time about overheating.

3. Adjust the new packing material to drip a bit underway but not at rest which will likely prevent overheating.

4. Adjust the new packing so it drips a tiny amount at rest which will definitely prevent overheating.


Thoughts? If you recommend option 1, what would you recommend for packing material?


Thanks in advance.

I'd go with option 3 (which may or may not give an occasional drip while stopped). And check temperature and drip rate the first couple of times you go out (both at low speed and on plane if possible).

If it seems to be getting hot or requires excessive drips for cooling, then pull it and put something else in (can be done in the water).

We used it quite successfully on what is now described here as a semi-displacement boat, which is a form of planing boat. We went at displacement speed about 90% of the time. Regardless, I questioned the yard about it, a good one, and they said that's all they used no matter what kind of boat. It dripped a tiny bit underway. 5 years and well over a thousand hours later, it was still doing just fine.

I’ve used flax for the last 12 years and want to switch to GFO. The box is one with the big nut holding the flax and it screws onto the the shaft tube. Is there any reason not to use GFO like overheating etc? The shaft alley runs under the galley deck so I would love to get rid of the drip, its humid enough here in S. Louisiana.

caltexflanc said:

We used it quite successfully on what is now described here as a semi-displacement boat, which is a form of planing boat. We went at displacement speed about 90% of the time. Regardless, I questioned the yard about it, a good one, and they said that's all they used no matter what kind of boat. It dripped a tiny bit underway. 5 years and well over a thousand hours later, it was still doing just fine.

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This is what I was hoping to read. Thanks for sharing a real-world anecdote. I will leave it in place and adjust to drip a little underway.

rslifkin said:

I'd go with option 3 (which may or may not give an occasional drip while stopped). And check temperature and drip rate the first couple of times you go out (both at low speed and on plane if possible).

If it seems to be getting hot or requires excessive drips for cooling, then pull it and put something else in (can be done in the water).

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Thanks, that's where I was leaning. Seems to be the most pragmatic solution.

Gulf Comanche said:

I’ve used flax for the last 12 years and want to switch to GFO. The box is one with the big nut holding the flax and it screws onto the the shaft tube. Is there any reason not to use GFO like overheating etc? The shaft alley runs under the galley deck so I would love to get rid of the drip, its humid enough here in S. Louisiana.

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I have the same type of stuffing boxes and have been using the GFO quite successfully for the last 5 years.


Ken

All packing has a rating for feet per minute (FPM).

Packing is not made for the recreational marine market, it is repackaged/repurposed from the industrial market and purchased by the pound.

Gore GFO is an ePTFE, not to be confused with PTFE (aka Teflon)

The little e stands for expanded. Gore patented the process of expanding PTFE during fabrication, thumbed their nose at DuPont, sued Garlock, and made billions.

The patent has since expired and ePTFE can be made by anyone. That's why you can buy all sorts of waterproof footwear and rain coats now.

Gore GFO is good for 4300fpm.

Pretty much any ePTFE packing with a similar yarn braid will provide the same results.

Recreational boat shaft packing is a really easy application. Water, low shaft speeds and low differential pressure.

I'd try it and see how it performs.

I've been using the moldable for over 35 years with success. Very little drip and the housing stays cool.

I adjust it loose at first and once underway tighten a little at a time while checking temperature.

I recommend GFO packing. On my previous boat, I was going to replace the conventional stuffing box with a PYI dripless to have a dry bilge until I read good reviews on GFO packing on the GB Owners forum. Cheap as I am, I went the GFO route and glad that I did. The packing worked great and kept my bilge dry. 8 to 10 years later I replaced the packing as part of a routine maintenance and found the old packing in remarkably good shape. My current boat has PYI Dripless that is in need of replacement as it is 10 years old. So next week I will be replacing it with a conventional stuffing box using GFO packing.

Thanks to you all for the comments, GFO it is. Now to the boat to figure what size to buy.

So....best source for GFO packing? Can't locate on Defender. Frankly, not even sure I know what it is, but take the recommendations at their word.

Thanks in advance

Peter

mvweebles said:

So....best source for GFO packing? Can't locate on Defender. Frankly, not even sure I know what it is, but take the recommendations at their word.

Thanks in advance

Peter

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Defender doesn't sell the Gore branded version, but they sell a version by Western Pacific Trading that's basically the same thing. I've also seen a version made by Palmetto listed on Amazon.

Really, you have another option. Do nothing.

Maybe try a half turn on the packing nuts, maybe just leave it alone.

pete

rslifkin said:

Defender doesn't sell the Gore branded version, but they sell a version by Western Pacific Trading that's basically the same thing. I've also seen a version made by Palmetto listed on Amazon.

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Thanks - found it on Amazon "Gore GFO" search. Like the OP, just need to figure out the right size.

Peter

I use duramax shaft packing no drips even when under way fore 10 years

"Like the OP, just need to figure out the right size."


Slide a drill bit in as a measure.

FF said:

"Like the OP, just need to figure out the right size."


Slide a drill bit in as a measure.

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FF, every now and then you come up with incredible words of wisdom and know how! Thanks for that tip!

Not to go completely off topic of your question... But why not go with dripless seals instead? I have done it on my last 2 boats. Best decision ever. I now have clean dry bilges. If water is in there now, it's from someplace it SHOULDN'T be coming from... Just a thought...

Scottwb96 said:

Not to go completely off topic of your question... But why not go with dripless seals instead? I have done it on my last 2 boats. Best decision ever. I now have clean dry bilges. If water is in there now, it's from someplace it SHOULDN'T be coming from... Just a thought...

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Dripless seals are functionally nice, but there's some concern about failure. When one fails, the failure modes are usually worse (and harder to fix in the water) than a leaky stuffing box.

rslifkin said:

Dripless seals are functionally nice, but there's some concern about failure. When one fails, the failure modes are usually worse (and harder to fix in the water) than a leaky stuffing box.

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There is also the expense if the boat is not already fitted with them. Yes, traditional stuffing boxes do require *some* maintenance, but its minimal especially if one uses modern packing materials.


I have the Western Trading packings in my boat and 5 years so far with no issues or adjustments required at all.



Ken

Agreed. Even if I had to re-pack the stuffing boxes every year, it would still take a long time to come up to the cost of a dripless seal (assuming I do the repack myself).

Valid reason.... But, I feel the failure rate of DS is so low and as long as you don't try to run them for 20 years without any maintenance, should be alright... The last ones I replaced on my new boat had been on for over 15 years and still almost looked brand new. Only reason I replaced them was because I was already doing shaft/prop work. Had everything apart already, seemed like a good time/money investment...

bluemainship said:

I use duramax shaft packing no drips even when under way fore 10 years

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Our boat had Duramax packing in it when we bought it and it didn’t leak. I just replaced the hose, clamps and packing on my port shaft and went with Duramax because we didn’t have any issues with it before.

Duramax packing is braided ePTFE material imbibed with graphite.

It is equivalent to GFO.

Isn't there some concern about corrosion of the shaft when you use packing that contains graphite? Or something like that..???

Our boat had used Duramax for 19 years. I replaced the hose, clamps and packing on one shaft this winter. Where the packing rides on the shaft there was no evidence of any damage, just shiny surface.

I’ve used the duramax for 5 years and removed a shaft for inspection and found no issue whatsoever.

Ken

Thanks guys. I remember it being a discussion but couldn't remember the final answer.

No shaft damage here either after 8 to 10 years.