Hello, I have a Hunter 30' 1979 model and have seen some replies on here about a dripless system instead of a packing of the prop shaft could anyone give me some info on this?
Dripless
- Thread starter lee oakley
- Start date
Look right here in the shop for PSS (shaft seal). Look under Engines Parts/Drive Train/Shaft Seals ...
I'm a bit anal about having a dry bilge and have installed dripless seals in my last 3 boats. If I ever have any water in the bilge, I know I have a problem and will hunt it down and fix it. With a dripping gland and a wet bilge you assume the water is from the gland so no reason to look any further.
There are pretty much two camps, the "for" crowd love the dry bilge, and the "against" crowd who will tell you that the trip to the bottom is imminent.
We have a PSS and are still floating.
( so far today anyway )
We have a PSS and are still floating.
( so far today anyway )
To fix a traditional pack leak is very simple. To fix a leaking dripless is a haul with a several step project to follow. I favor simple and a traditional pack can be installed to achieve near dripless anyway.
Charles
Charles
I had wanted to fit a pss dripless but then I read an article that somewhat say...with packing you're still floating in days with dripless you sink in minutes. I stayed with packing for now.
The 2 types of "dripless" shaft seal I found in the SBO shop. I have had great success with #1.
1) This is mine PSS...
http://shop.sailboatowners.com/cu/detail-shaftseal.php
2) This one was new to me Norscot...
http://shop.sailboatowners.com/prod.php?5021/Norscot+Dripless+Propeller+Shaft+Seal+Kit
1) Is a mechanical compression seal with rotating Stainless face against a Carbon (not Graphite) wear plate. The bellows are the compression "spring", and if bellows failed/leaked would allow water to flow, albeit slow, to enter your boat. If the seal shattered and the bellow busted, big time flow. Seal cooling/lubricating is done by forced sea water purge or using boat's water depth to back flow enough sea water to keep seal face wet and cooled at low speeds of a sailboat. Normally recommended changing at least every 10 years by maker. So far for me, excellent service (2.5 years), and I inspect the stationary bellows when I check oil and fuel filters each time I prep my boat for a sail.
2) Is a Double Lip Seal. Automatic Trasmission Fluid (ATF) is the "oil" lubricant to reduce the elastomer sealing "lips" wear as the shaft rotates. Failure would be like the packing gland type slow leak and should be more annoying than catastrophic. Shaft preparation and alignment is the installation "headache". This type seal is great as long is your engine mounts are healthy or shaft alignment is maintained. I speak about this type seal from industrial application and NOT my sailboat experience.
I would search SBO for dripless seal, PYI, PSS for many facts and opinions.
At least for my boat, I will stick with type 1. When I take my boat out for bottom paint in 3 years, I will probably put in a new one or at least pull and inspect the carbon wear face.
Jim...
I, too, like to keep things simple. However, my packing gland was a PITA to get to. Went with the PYI dripless years ago and have not had a problem. Replaced it in Jan. this year after eight years while I was on the hard, anyway. You're going to get all kinds of conflicting views on this subject but, if it were me and the packing gland was easy to get to, that's what I would stay with.
This is my main concern. I'd much rather get some advance warning over a sudden catastrophic failure.
O.K. based on the average answers .Some good and some that have me concernd on putting something else in I believe that I will stay with the packing since I am 6 hours from the marina and am planing a trip from pemlico to edisto s,c. major faliure would be terrible thank's for the advice
If they really existed the manufacturer would have been sued out of existence long ago and our insurance carriers would be basing rates on weither our boats have them. Either system can have failed bellows.
Never heard of any failures.
It is the Bellows that stops the ocean intrusion.
Treat the bellows like a sea cock hose. I inspect my hoses and bellows for stress and cracking. The bellows are in compression and do flex with engine thrusts.
The reason they are called "Bellows" (and not hose) is the the flex design.
IMHO a well designed seal.
Jim...
PS: I think the fear is no shut off valve. Have a big wire tie and old inner tube nearby if you are nervous. Static failure of the bellows would be rare.
Much less smell in the bilge and there could possibly be a case made for less friction. The differences are probably so small as to not bother mentioning.
This is a mechanical system, not unlike every other mechanical system on the boat. It's no more or less subject to failure than the mast hitting a bridge and coming to sit with you if you're not paying attention, or the hose clamps coming off the raw water inlet and wondering why the temperature alarm was going off.
We too are over an hour from mooring to trailer - it just means you have to be that much more diligent. What it doesn't say is that you need to take care of your stuff. The packing in a gland isn't gonna last 20 years, or never need attention either, and if you're not prepared, capable or willing to attend to it, (in either case) the boats going to become a crab trap sooner or later.
This is a mechanical system, not unlike every other mechanical system on the boat. It's no more or less subject to failure than the mast hitting a bridge and coming to sit with you if you're not paying attention, or the hose clamps coming off the raw water inlet and wondering why the temperature alarm was going off.
We too are over an hour from mooring to trailer - it just means you have to be that much more diligent. What it doesn't say is that you need to take care of your stuff. The packing in a gland isn't gonna last 20 years, or never need attention either, and if you're not prepared, capable or willing to attend to it, (in either case) the boats going to become a crab trap sooner or later.
I wouldn't rely on the bellows to compensate for a gross misalignment or reduce vibration. It is perhaps a "Thrust change" shock absorber helping the motor mounts a bit.
All shaft seals will wear with time.
Packing gland...you adjust and can cause a shaft grove.
Mechanical Compression... bellows compression adjusts as the Carbon faced seal wears.
Lip Seal... the sealing lip rings wear, ATF to lube and reduce shaft and lip seal wear.
Industrially, the mechanical compression seal is the most reliable and maintenance free seal and why I switched to PSS.
Let me correct this slightly..
The hardened Carbon composite material DOES have some Graphite in it. Insignificant galvanic corrosion impact on the Stainless Steel shaft and rotor.
Jim...
In an earlier post I stated that I had no problems with my PSS. While that part is true, a month before I changed it out, I had a rather significant drip from the seal. It, however, was not a fault of the unit. A piece of debris, grass, a speck of sand, something apparently got between the carbon flange and the rotor. I would turn the shaft by hand and the drip would stop. Move it a bit more and the drip was back. This only happened at the dock and not when motoring or sailing. Two weeks before haul-out, the drip stopped completely. Changed it out, anyway, as it was eight years old. It's still in usable condition and is kept as a spare.
Here is one testimonial by a TowBoatUS operator about dripless shaft seal failures and sinkings:
http://www.passagemaker.com/articles/technical/running-gear/dripless-shaft-seals/
It caused me to go with the Norscot fitting.
http://www.passagemaker.com/articles/technical/running-gear/dripless-shaft-seals/
It caused me to go with the Norscot fitting.