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Old 23-08-2013, 13:53   #1
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New "Big" boat owner

Hello all - first post here. I'm about to take possession of a 1991 Sea Ray 350 Sundancer. and I have a boat load of questions . This is my first boat with inboard engines.

The drippless shaft seals leak (quite impressively) at higher RPM (no leak at low or idle RPM). I don't know yet what brand they are or if they can be adjusted to stop leaking. The questions I have are:

1. Why are they SO expensive?
2. Which brands are best? (I like the PSS seal)
3. Can the seals be replaced while the boat is in the water?
4. Will I be able to insure the boat without fixing the seals?

I think I'll limit this discussion to the shaft seals for now.

Thanks,

Tom
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Old 23-08-2013, 14:54   #2
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Re: New "Big" boat owner

1. Not exactly sure.
2. PSS is the brand that most people mention, and seems to have a good rep.
3. It is probably "possible" if you have a big enough pump, some serious balls, and have previous experience doing the work. The job will be infinitely easier (and most likely much better done) with the boat hauled. The shaft should be pulled and checked, and might require machining for the new seal. I can't imagine that you'll find a professional mechanic who would agree to do it with the boat in the water.
4. If it's been surveyed, then the leaking seals were (hopefully) flagged as a priority safety/structural/CG regs issue by the surveyor. The insurance company will require you to remediate any of those items within a certain period and to sign a document confirming that the work has been done.
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Old 23-08-2013, 15:19   #3
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Re: New "Big" boat owner

With the new graphite braided packing material, I'm surprised that people are still enamored of drippless technologies. Why buy something that will soon wear out, and could sink your boat when it fails?

Graphite packing glands are the way to go.

Welcome to the forum, by the way.
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Old 23-08-2013, 15:21   #4
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Re: New "Big" boat owner

Bash,

Please tell me more - I know nothing about stuffing boxes.....
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Old 23-08-2013, 16:25   #5
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Re: New "Big" boat owner

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Originally Posted by CruiserTom View Post
Bash,

Please tell me more - I know nothing about stuffing boxes.....
Here is a link to a web site by forum member Maine Sail that shows pictures and instructions that will show you all about the traditional stuffing box.


Re-Packing A Traditional Stuffing Box Photo Gallery by Compass Marine at pbase.com
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Old 24-08-2013, 08:53   #6
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Re: New "Big" boat owner

Quote:
Originally Posted by CruiserTom View Post
Hello all - first post here. I'm about to take possession of a 1991 Sea Ray 350 Sundancer. and I have a boat load of questions . This is my first boat with inboard engines.

The drippless shaft seals leak (quite impressively) at higher RPM (no leak at low or idle RPM). I don't know yet what brand they are or if they can be adjusted to stop leaking. The questions I have are:

1. Why are they SO expensive?
2. Which brands are best? (I like the PSS seal)
3. Can the seals be replaced while the boat is in the water?
4. Will I be able to insure the boat without fixing the seals?

I think I'll limit this discussion to the shaft seals for now.

Thanks,

Tom

It might not be the seals leaking, but rather the hoses that inject cooling water to the seals. IOW, might just need some tightening, new clamps, whatever.

PSS and Tides and the most common makes; both seem to have a good rep. The ones that are "best" might be the ones you already own

ONE of those (TIDES) is usually installed with a new lip seal already on the shaft. The old lip seal can be removed and the new lip seal slid down into place while in the water.

See manufacturer's websites.

-Chris
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Old 24-08-2013, 09:40   #7
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Re: New "Big" boat owner

You can easily tighten the PSS seal (ie squeeze bellows in direction of stern). Unless totally worn or some other problem (eg shaft alignment) this should stop leakage. It takes a few hours run time to "polish" the carbon face seal. Despite the concerns about sinking boats, very many vessels have these types of seals. I have not heard of them (I expect someone to come up with those I missed!!) actually failing and sinking a boat.
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Old 24-08-2013, 10:04   #8
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Re: New "Big" boat owner

Quote:
Originally Posted by Bash View Post
With the new graphite braided packing material, I'm surprised that people are still enamored of drippless technologies. Why buy something that will soon wear out, and could sink your boat when it fails?

Graphite packing glands are the way to go.

Welcome to the forum, by the way.
Yeah, why spend big bucks when a $3 item will work. Seems like I've seen as many posts about dripless seal issues as packing issues on this forum.
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Old 24-08-2013, 10:09   #9
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Re: New "Big" boat owner

But if your boat was not built with a stuffing box, you are stuffed!!!
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Old 24-08-2013, 13:06   #10
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Re: New "Big" boat owner

Propeller shafts can't be retrofitted with a stuffing box??? I can't see why not.
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Old 24-08-2013, 16:01   #11
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Re: New "Big" boat owner

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Propeller shafts can't be retrofitted with a stuffing box??? I can't see why not.
I don't either. As long as there is a shaft log with a provision for attaching the stuffing box hose which I think even dripless seals use (guessing since I don't have a dripless seal), then it's a straightforward change. It will require hauling the boat and pulling the prop shaft out.
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Old 25-08-2013, 08:30   #12
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Re: New "Big" boat owner

They are suppost to leak a bit under way to lub between the color a.d the bellows. also as the rpm of the engine increasez so does the raw water flow and pressure. You can increase the pressure against the bellow by moving the ss collar back. If the water leak is coming from under around the collar you could wrap emergency tape around the shaft and collar you. There probably is nothing major wrong with the dripples. As long as it does not drip when the engines running and or shaft turning.
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Old 25-08-2013, 08:47   #13
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Re: New "Big" boat owner

Quote:
Originally Posted by chrisjs View Post
You can easily tighten the PSS seal (ie squeeze bellows in direction of stern). Unless totally worn or some other problem (eg shaft alignment) this should stop leakage. It takes a few hours run time to "polish" the carbon face seal. Despite the concerns about sinking boats, very many vessels have these types of seals. I have not heard of them (I expect someone to come up with those I missed!!) actually failing and sinking a boat.
As the owner of a 12 year old PSS shaft seal, I was also concerned to read this.

I've never heard of boats being sunk by them. Is there a catastrophic failure mode?

I had mine inspected while my boat was out of the water for a refit last winter. The engineer said the seal was fine with plenty of life left. Nevertheless, I wonder whether I'm pushing my luck.

It doesn't leak a drop and has never given me the slightest trouble. It is one of those which is pressurized with sea water from the raw water circuit of the main engine.
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Old 25-08-2013, 08:52   #14
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Re: New "Big" boat owner

Answering my own question: Dripless Shaft Seals | PassageMaker

Fairly sobering stuff. I think I'll just replace mine entirely this winter.
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Old 25-08-2013, 08:56   #15
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Re: New "Big" boat owner

Perhaps I was unclear. I was not suggesting that boats had sunk - just the opposite!!
I have a PSS from 1999, that was replaced as routine preventative service in 2008. At that time PSS recommended replacing the rubber every 6 years or so - I think that has changed. There was no indication whatever of deterioration in the mechanical seal or the rubber bellows on the removed unti. The new unit is fine after 5 years and I have no intent of doing another preventative replacement in the near future. I will add that we have a slow turning trawler prop., so perhaps with high speed props. the maintenance may be more critical. But again, I think the stories about major failures are hyped and the result of inadequate attention by owners. I will also add that our PSS is "locked" in place witha large shaft zinc to prevent the unit relaxing/sliding back along the shaft and leaking. This should be routine when installing these units.
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