How many rings of packing for the stuffing box?

[Regal2800]

mine was made by Gore.

http://www.gore.com/en_xx/products/s...tructions.html

I have it dialed in now but it really was a pain. After i installed it i was talking with the head of the yard and he was saying that on the larger shafts (2.5"+) they only use the traditional flax stuff. That the gore tex stuff didn't do well on the larger shafts. I dont know if there is any truth to this or not.

[Pascal]

150 deg at slow speed? Geez...

I think mine took 4 rings but yours may be different. I don't see how you can put too many rings in there, sure they compress a little but not enough to allow extra rings

Goretex is dripless but should be set with a slight drip and then adjusted after running by tightening just enough to be dripless. Temp is the big red flag though. Can't believe your guy screwed it up... It s really one of those DIY jobs

Mel, one bilge pump should easily keep up with a bad stuffing box. What size pump do you have?my 2000 easily keeps up with the box open AND the stuffing pulled out!

[northshoreone]

I just repacked my shafts with the new gortex packing on my 70 which has 3.5 in shafts...tightened them just enough to stop the drip but haven't run the boat yet. I am heading back to it next week to run it a bit before I head to the Keys. Mine took five rings...I think I could have made it six but I believe that wouldn't give me enough thread left and saw no need to go beyond five. I've heard that the new material turns it basically into a dripless shaft! Time will tell....I will be keeping a close eye on them on the way to the Keys for any heat issue's.

[Mel Tucker]

150 deg at slow speed? Geez...

I think mine took 4 rings but yours may be different. I don't see how you can put too many rings in there, sure they compress a little but not enough to allow extra rings

Goretex is dripless but should be set with a slight drip and then adjusted after running by tightening just enough to be dripless. Temp is the big red flag though. Can't believe your guy screwed it up... It s really one of those DIY jobs

Mel, one bilge pump should easily keep up with a bad stuffing box. What size pump do you have?my 2000 easily keeps up with the box open AND the stuffing pulled out!

Pascal,

You are certainly right that my pumps should have been able to handle the incoming water. All I know is that all three bilge pump lights were on meaning they were pumping. However, the water was already 3 inches ABOVE the shaft and overflowing the ribs!! In addition, they were only going to pump until they ran out of battery charge.

My next job will be to replace all bilge pumps because I have no idea their brand, capacity, etc. I don't know if being in 2 1/2 knots of current was increasing the water flow in or not. It was disconcerting to be reaching under water to hand start the locking nut, etc to get the water stopped. In any case, its a good reason to advise anybody that changes packing to be careful to test for heat, leaks, sufficient threads, lock nut tightness, etc and to not just assume the yard did it right.

Mel

[rsmith]

Don't you need a slow drip to keep oxygenated water on the shaft to prevent crevice corrosion? I've often wondered how that works out on dripless bearings when they sit a long time. Thoughts anyone?

Bobk

Any metalurgists out there can answer this? I know we had corrosion problems in some of the heat treating furnaces we used to sell that operated with oxygen depleted processes.

[MikeP]

I think there is no simple "on paper" answer to the question. It is well known, of course, that crevice corrosion can eat up SS when there is no circulation of water.

BUT, does the Gore packing on an SS shaft prevent adequate circulation? Just because no water is coming into the boat may not mean there is insufficient circulation. So, IMO the only way to answer the question is to look at multiple examples in actual use. As I said, a check on one of our shafts showed no sign of any corrosion after several years of non-dripping Gore use. I realize that one example doesn't mean anything due to the variables - water conditions in the cruising area, maybe water temperature, specific tightness of the packing, type of SS used for the shaft, etc, etc.

IOW, perhaps - and this is just speculation - if one tightens the packing to where it JUST stops dripping, there is still sufficient circulation of water to prevent any problem but if the packing was much tighter, there would be a problem. Seems to me the only way to answer it would have to have some sort of standardized testing to determine if any problem exists. This might result in an answer that indicates that X type of SS shaft is OK while Y is not or that it's OK if the packing is done a certain way or if the water temp is generally above or below some temp.

Would definitely be interesting...

[bostonhatteras]

I'm no metallurgist and I have installed pss seals on my boat so get off this thread right! The boat owners guide to corrosion sums up the discussion of immersed 304, ,316, and the different alloys of aquamet etc by saying 'the conclusion is that if we want to use stainless steel below the waterline, we must be sure that the surface of the metal is exposed to constantly flowing water and we should take precautions to avoid crevices. Because we cannot eliminate all crevices, we should take steps to seal those we cannot eliminate. Finally, we should not use stainless steel fasteners in wood or fiberglass underwater'. The reason I went with pss seals is it was either replace the pitted shafts and keep the stuffing boxes or replace the stuffing boxes with something that would accommodate the pitted shaft. The shafts were too pitted to seal. I chose the later. 12 years later and no leaks or other issues. Getting back to corrosion, the book further states that chlorides in the water ranging from 1000 ppm to 18000 ppm in fresh water and seawater, respectively, is the main determinant of stainless corrosion. Quoted again, 'the contaiminants-industrial and agricultural pollutants-can significantly increase the corrosivity of these waters. Thus, corrosion damage is very much a function of the specific nature of the water in which the boat operates'. I gather from reading his statements that no amount of cathodic protection will remove the risk of crevice corrosion and he further states that removing the risk of corrosion requires a water movement of between 3 to 5 ft./second. Sounds like the boat just can't stop moving to ensure that requirement! Also the corrosion resistance is a factor of oxygen combining with the stainless steel on the surface and creating a passive or passivated layer that resists the corrosion. If this passivated layer is scratched or constantly rubbed away as in a too tight stuffing box then the chance for corrosion is that much greater. Sounds like you get it as good as you can and play the cards your dealt. Can I get my mail order metallurgy diploma now? Lol

[MikeP]

Wow, I need a degree just to read that!

I guess I just have to assume that gore packing on our boat in LI sound/Chesapeake bay over 5 years with whatever type SS the 1980 Hatt shafts used plus the temp of the water plus the relative tightening of the packing luckily hit the proper parameters and resulted in no crevice corrosion!

[Pascal]

Mel

The fact that all 3 lights were on just tells that the float switches and lights were working, doesn't mean the pumps were pumping. In fact if all three were on it means that at least one, if not two, were not pumping...

Anything smaller than Rule 2000 doesn't belong on a boat

[Canuck Dennis]

What about the theory that when the boat is cruising forward the water flow into the shaft packing is actually under a vacuum ??