Flax nut on rudder post keeps leaking

[IguanaSwim]

I put in new flax under the nut, layering in the ends to avoid gaps. I keep tightening it till it stops. Yet on rough sails it leaks a lot. We have a 60 foot maple leaf cutter. I am tightening the top nut, holding the lower in place. The lower seems tight enough.

[Hartleyg]

You say you've tightened it until it stops - what is the friction on the shaft at that point? If you have enough packing installed, you should be able to stop the shaft completely before you bottom out the nut. (not that you should do that, but it should be possible)

[IguanaSwim]

Thank you, Hartley. Can you please explain this phrase:
“what is the friction on the shaft at that point?”
Much obliged.

[capt jgw]

Sounds like you need new packing. It gets compressed and hard and doesn't seal well anymore. It lasts longer on a rudder than a prop shaft, but not forever. Can be done in the water but it's a little scary, water will come in when you back the nut off and it can take a while to dig the old packing out. Better done out of water, you can take your time.

[IguanaSwim]

Thank you Capt

Even though I replaced it nine months ago?

[Hartleyg]

"The friction on the shaft" - what I meant was, you should be able to tighten the pressure on the packing enough to make the shaft very difficult or impossible to turn. Clearly you wouldn't leave it that way, but if you don't have enough packing (or the packing is old and compressed) to do this before the tightening nut hits the end of the thread, then you don't have enough packing installed.
Some of these packing assemblies take a LOT of packing! Be sure to use modern packing materials - tefgel or the like for the lubricant, and synthetic packing flax. Also make sure you are using the right size to fully fill the gap between the housing and the shaft.


Hartley
S/V Atsa

[donradcliffe]

The bottom nut is a locknut. If you want to tighten the packing, you need to back the bottom nut off a few turns.

Adjusting a rudder packing is a bit different than adjusting a propeller packing. The water pressure on the rudder packing is a function of boat loading and boat speed. If you load the boat up with cruising gear you raise the water line and it will leak more, but in general it will not leak until the stern wave rises, which is a function of boat speed. So you have to take it out and sail fast to test it.

As a previous poster said, you can tell how tight the packing is getting by how hard it is to turn the steering wheel. I would adjust it until the wheel feels stiff, then back it off 1/8 of a turn, and tighten the locknut. Go sailing, and repeat as necessary.

Once you get it right, it should last 9 years or more, unless the surface of the shaft is damaged.

[Searles]

Is there a grease point under the bottom lock nut,adding grease stops the packing drying out quickly in salt water also helps to for a seal ,and lubricants the rudder shaft ,with bronze and s/s greasing under the packing is a good thing .⚓️⛵️

[Bowdrie]

Originally Posted by IguanaSwim

I keep tightening it till it stops. Yet on rough sails it leaks a lot. We have a 60 foot maple leaf cutter. I am tightening the top nut, holding the lower in place. The lower seems tight enough.

"Tightening until it stops".
Stops against what?
You don't tighten until it stops against the lower nut, you screw down the lower nut, (closer to the flange,) then you tighten the packing gland to stop leaking.
You don't "hold the lower in place".
If you can't screw down the lower nut further, is it because of the heavy corrosion, or is it because there are no threads left?
The lower nut is a lock nut to stop the upper from rotating.
You may have to do a through cleaning of the threads to effect proper adjustment.
With clean threads and good packing, (and grease,) you should be able to prevent leaks with little more than turning the upper nut by hand.

[HopCar]

What Bowdrie said. Loosen the lower nut before you try to tighten the upper nut. Sounds like the lower nut is preventing you from properly tightening the upper nut.
Once the upper nut is correctly tightened, tighten the lower nut against the upper nut to lock it in place.