SailNet Community - Reply to Topic
Thread: Shaft seal Reply to Thread
Send Trackbacks to (Separate multiple URLs with spaces) :
Post Icons
You may choose an icon for your message from the following list:

Register Now

In order to be able to post messages on the SailNet Community forums, you must first register.
Please enter your desired user name, your email address and other required details in the form below.
Please note: After entering 3 characters a list of Usernames already in use will appear and the list will disappear once a valid Username is entered.

User Name:
Please enter a password for your user account. Note that passwords are case-sensitive.


Confirm Password:
Email Address
Please enter a valid email address for yourself.

Email Address:


Human Verification

In order to verify that you are a human and not a spam bot, please enter the answer into the following box below based on the instructions contained in the graphic.

  Additional Options
Miscellaneous Options

Click here to view the posting rules you are bound to when clicking the
'Submit Reply' button below

  Topic Review (Newest First)
11-23-2006 11:03 AM
sailingdog Don't forget to put something in the photo, like a ruler, to give a sense of scale...
11-23-2006 09:43 AM
cardiacpaul if you've got a digital camera, a picture would help.
11-23-2006 08:38 AM
Edo Kazumichi Thanks for the input, folks, even if it is conflicting.

What do I have? Well, I don't know the brand but it's about four inches long, bronze and has a grease tit. There's no way to open it up to pack in anything. How would I go about finding the brand and thus the operational specs on it - i.e. if it should drip, when and how much?
11-22-2006 04:39 PM
FrankLanger CardiacPaul, thanks for the great links--they answer just about any question one could have about stuffing boxes, seals, etc.
11-22-2006 04:03 PM
k1vsk Kind of difficult to respond after you already received a number of conflicting answers...
First, I'd suggest you check out the types of shaft seals there are as the type you have will dictate how tou should maintain it. The previous answers all seems to imply you have a certain type which is difficult to know without a further description. There are a number of how-to boat maintenance books available should you want to study up.
Of the various seals, some are supposed to leak, albeit slowly, and others are so-called dripless (and there are a few different types of these as well). Again, what you should do depends on what type you have. The good news is that it is apparenly leaking slowly so no worries as they seldom fail catastrophically.
Let's assume you have the older type grease filled seal and you have used the correct grease which is not water soluable. It should not leak at rest but may when turning. If this is the case, you're fine - if it is leaking at rest, there are two likely possibilities:
1. wrong grease, and
2. air pocket entrained in the grease container.

If you can be a little more specific about what you have and what grease you used, maybe we can eliminate the guessing of what might be a problem.
11-22-2006 03:56 PM
camaraderie "A bronze shaft seal" sounds like a stuffing box to me. Edo...are you sure what you are describing is a shaft seal and not a stuffing box?
If it is a stuffing box then a drip or two a minute while underway is exactly how it should be performing.
11-22-2006 03:46 PM
cardiacpaul the stuffing box is lubed-sealed with either water, flax, some type of new fancy-schmanchy (technical term) no stick-um packing that keeps it turning and the dry in, and the wet out. . There really should be no water ingress into the boat. period.

good links...

Some bronze bushing so do have a carbon/petroleum based lube imbedded in the bushing itself, but, this is not a sealing device, its a lube.

The cutlass bearing is a whole 'nother breed o'cat.
heres a really good link....
11-22-2006 02:18 PM
FrankLanger CardiacPaul,
I'm just trying to understand and continue to learn: how is this bronze seal different from a stuffing box which is supposed to drip a bit to lubricate the prop shaft? And if it's not supposed to leak any water, what lubricates the bronze seal/prop shaft when it's rotating? I vaguely remember that some bronze bushings are self-lubricating--is that the answer to my first question?
Thanks for any information.
11-22-2006 09:14 AM
cardiacpaul short answer.... it shouldn't be leaking at all, get it fixed, fast. It will get worse. A "dampness" is ok, but a drop is a drop, not good. (after typing this, I'm not sure this is making any sense at all, work with me, ok?)

longish answer.., the dirty cream color is the water emulsifying with the grease.
The reason why it doesn't leak "at rest" is there isn't enough water pressure to move past (displace) the grease when the shaft isn't turning.
11-22-2006 08:56 AM
Edo Kazumichi
Shaft seal

I've got a bronze shaft seal. It was leaking so I put in some grease. Now it leaks about 1 drop ever 2 or 3 seconds when the engine is in gear but none at all when the engine is shut down. I know these things are meant to leak a bit but is this rate normal? Also, grease the color of dirty-cream has extruded from the front of the seal. Does this just mean that I put in too much?

Can somebody give me an idea of what's normal for this thing?

Posting Rules  
You may post new threads
You may post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is On

For the best viewing experience please update your browser to Google Chrome