Trawler Forum

Trawler Forum (
-   Power Systems (
-   -   Dripless Stuffing Boxes (

marinetrader 10-07-2010 11:23 AM

Dripless Stuffing Boxes
If your*trawler has inboard engines, odds are it is fitted with a stuffing box to provide a watertight seal for the prop shafts. Stuffing boxes are also used to seal rudder posts that penetrate the hull below the waterline too.

Stuffing boxes are actually the seals that allow prop shafts and rudder posts to come into the yacht but yet keep the water out.* Today's stuffing boxes are made a bit differently than those of just a few years back, thus earning the name "drip less" seals. But this article is about the older boxes found on older trawlers.

The older stuffing boxes were just a compression fitting and sleeve filled with a flax material; they were intended to "leak" a little with the water providing essential lubrication.* A drip or two a minute is about right.* But if want dry bilges, you can make them drip less too.* How?* By replacing your current flax packing with a new material called GFO Packing, made by Gore-Tex.* The new packing is made of Teflon thus permitting the packing to be compressed to a point where no water will leak from the stuffing box itself.* We have used it on the Patricia Ann for 2 years and have dry bilges.*

Replacing your packing is simple too.* Remove the four nuts that holds the stuffing box together and work the fitting apart.* You may need to strike it with a mallet to loosen it.* You will also need a packing removal tool available at any boat yard.**

Remove the existing packing by using the extraction tool like a corkscrew and force the old packing out.* You can do it while your*trawler is in the water as you will only take on about 1/2 gallon of water. Over time, after the packing nut has been tightened a few times, the packing gets so compressed that it becomes hard enough to actually wear a groove in the propshaft -- a condition you want to avoid.* On fast power vessels, the shaft packing should be replaced at least every 2 years.**Slow moving trawlers*may not need to have the packing replaced for five years or more, but when the stuffing box starts requiring frequent adjustment, it leaks too much or if it begins to feel warm, it's time.

If you can remove the old packing in one piece, use it to learn what size packing you need. If it comes out as distorted wads of gunk, then measure the distance between the shaft and the inside of the packing nut to determine the correct packing size.

When all of the old packing has been removed, place one new section of new packing back into the compression fitting and push the sleeve back into place by hand.* The easy way to do this is to wind the packing around the shaft in some accessible location and cut across the overlap with a razor knife on an angle making 4 individual rings of packing.* Roll one of your cut lengths into a ring around the shaft and push it into the stuffing box.* Tamp it evenly with a little dowel or a square screwdriver to press it all the way to the bottom of the box. Push a second ring into the stuffing box on top of the first one, staggering the joint about 90 degrees. Add a third layer, then the fourth, each time staggering the joint. If you don't seem to have room for the fourth layer, hand tighten the adjusting nut to push the other rings deeper, then remove it again to see if this made room for an additional ring of flax.

By the 4th section, any water flow will have about stopped.* Now press the compression fitting into place as much as you can by hand. Next screw on the two compression nuts and tighten with a wrench to continue to apply pressure to the packing.* Not to much however, just a firm application until the leak stops.* You will need to probably adjust it a bit after you run the boat the next time.* Finally, install the remaining 2 lock nuts to finish the job.

An everyday error is winding the new packing around the shaft as a continuous piece. Packing installed this way will not seal correctly. It must alternatively be installed as a series of stacked rings. This necessitates cutting the packing into lengths that just circle the shaft with ends touching preferably with cuts on an angle.

Now you can brag to all of your buddies that you have drip less seal on your boat too.

Baker 10-07-2010 11:36 AM

RE: Dripless Stuffing Boxes
Also, when fantasizing about a dry bilge, realize there are other contributors to water in the bilge....namely air conditioning condensate. You are gonna have to account for that if it has not already been. Some showers drain straight into the bilge although most have a dedicated sump. I have seen people use shower sump set ups to drain their air conditioners into.

Bendit 10-07-2010 01:02 PM

RE: Dripless Stuffing Boxes
And hot-water cylinder relief valves...

Pineapple Girl 10-07-2010 05:37 PM

RE: Dripless Stuffing Boxes
we just realized last night that all that water in our bilge is from our port shaft packing so this is very timely for us!* thanks

Arctic Traveller 10-07-2010 07:28 PM

RE: Dripless Stuffing Boxes

Baker wrote:

....namely air conditioning condensate.

Air conditioning??* Whats that for?.................Arctic Traveller


Marin 10-07-2010 07:53 PM

RE: Dripless Stuffing Boxes

Arctic Traveller wrote:Air conditioning??* Whats that for?.................Arctic Traveller
I think it's*a system by which the air is heated, or "conditioned," to make the interior of the*boat more comfortable during winter.


FF 10-08-2010 04:30 AM

RE: Dripless Stuffing Boxes
we just realized last night that all that water in our bilge is from our port shaft packing so this is

First step is to find out the size if the packing material the stuffing box needs.

Duramax , if you can locate it is probably the best to use , as it does not require a constant drip to take off the friction heat.

Keith 10-08-2010 04:53 AM

RE: Dripless Stuffing Boxes

Love this stuff and wouldn't be without it.

sunchaser 10-08-2010 08:58 AM

RE: Dripless Stuffing Boxes
FF - So you have twins?* Gotta love the irony here.

Pineapple Girl 10-08-2010 09:57 AM

RE: Dripless Stuffing Boxes

sunchaser wrote:

FF - So you have twins?* Gotta love the irony here.


Ff was quoting my reference to MY twins. Two Perkins ST6.3544s to be precise.

ralphyost 10-08-2010 03:21 PM

RE: Dripless Stuffing Boxes
I replaced my PYI dripless stuffing box in 2007. Had the tranny out, rudder and prop off so the shaft coupling could come off easily. It was an opportune time. My old PYI stuffing box had something like 4000 engine hours on it and was about 11-12 years old. Not bad.

Installation was not hard since the basics were set up as described above. Just follow instructions.

Bob Smith has told our MTOA group several times about some brands of stuffing box that have a catostrophic failure mode that is truly catostrophic. He had it happen to his boat. but it was not a PYI.


JMYSS 10-13-2010 06:07 PM

RE: Dripless Stuffing Boxes
Dripless is the way to go. While doing our overhaul, we went to a PYI dripless on our single engine. I like not having wet bilges, especially with an aluminum trawler...

Tidahapah 10-15-2010 03:32 PM

RE: Dripless Stuffing Boxes
Now Tim that's the difference.
Take me with a timber boat I love to have a little salt water down there so that things don't get dry and dusty.
occasionally I pump it all dry for a little clean up.
But being old fashioned I like a good stern gland with a little dribble but do admit to heading the way of the Gortex packing in the future.


Delfin 10-15-2010 09:27 PM

RE: Dripless Stuffing Boxes
I ended up draining a/c condensate, the E/R sink drain and the water tank pressure relief into a small shower sump that pumps overboard above the water line.* That coupled with a PYI allows for a dry bilge, which I cherish.* The questions about failure of dripless units causing problems are no doubt valid concerns, but since Delfin's stuffing box is very accessible and visible so the rubbers on the PYI can be routinely inspected, I'm not losing any sleep over leak potential.

xfedex 10-15-2010 10:54 PM

RE: Dripless Stuffing Boxes
I have always kept a *dry bilge by putting a little bucket under the stuffing box that fills every 4 or 5 days when we are cruising. If water is coming *from another source it is more obvious *and easier to track down.

rwidman 10-20-2010 08:46 AM

RE: Dripless Stuffing Boxes

xfedex wrote:

I have always kept a *dry bilge by putting a little bucket under the stuffing box that fills every 4 or 5 days when we are cruising. If water is coming *from another source it is more obvious *and easier to track down.

Why not install a bilge pump in the bucket and than not have to empty in manually?

Or install a commercial shower sump with the cover removed?* That would look better.


jleonard 10-20-2010 12:23 PM

RE: Dripless Stuffing Boxes
I installed a Strong Seal on this boat and my previous boat. Works differently than a PYI type being a "lip seal" like the front crankshaft seal on an engine.
I like dry and so far they have been flawless for me. I have a spare assembled to the shaft that is in position to be a quick replacement if a failure occurs.

All times are GMT -5. The time now is 05:38 PM.

Powered by vBulletin® Version 3.8.8 Beta 4
Copyright ©2000 - 2018, vBulletin Solutions, Inc.
Search Engine Optimization by vBSEO 3.6.0
Copyright 2006 - 2012