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I notice the stuffing box on my Catalina 36MkII leaking more than usual after launch. Not sure what may have caused it. It is probably fixed by adjusting the large nut a fraction. At least that is what I will do as a first step. Is it as simple as it looks, to use a large wrench and give it a twist and run the engine in gear to see what difference it makes? Thanks out there!
 

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How long has it been since you replaced the packing?
Most stuffing boxes have two nuts, one of which locks the other in place. have you ever tightened a stuffing box before? If not you might want to get an experienced friend to show you the process.
 

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al brazzi
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Its easy but do your homework first. Adjust a little at a time so it doesn't overheat and replace the clamps on the log (short hose) while you're at it with proper clamps with all SS non perforated style, ask if your not sure, pictures help. Packing might need to be replaced but maybe not.
 

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It's just possible for a cluts to use a single wrench on the gland and torque the hose to failure. Two wrenches prevent this calamity.
 

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I have a C34MkII with identical stuffing box arrangement, so I'll reactivate this thread. Before doing my (first) adjustment, I read the relevant sections of Calder's book and also MaineSail's website.

I think I have my issue resolved, so rather than a question I'll just post a comment. In my case I had 1 drop every 2 seconds at rest, and 1-2 drops a second when running (depending on RPM). I loosened the lock nut, etc. I ended up turning the compression (flax) nut about 1/3 of a turn, and water was still coming in. Then I suddenly felt a little resistance, and the water stopped abruptly. Unfortunately, when I put the motor in gear, I still had no drip, and I know this is a problem. The nut didn't get hot (up to about 80F after 10 minutes), but it still wasn't right to have no water. I did a lot of experiementation and no luck - either water all the time or no water ever.

Later I discovered that the nut can be adjusted by hand (thanks to some carefully placed PB Blaster that I had shot in a week ago. Without using a wrench, I could take it from frequent drips to no drip at all, and the amount of turning needed was only a few degrees. Very sensitive - could never find the right place if I were using a wrench. Finally, after multiple attempts, I found the sweet spot where it's dry when at rest and 3 drips/minute when in gear. Temperature rose to about 72F after 20 minutes of operation. I tightened the lock nut by hand, then used 2 wrenches very carefully, to make sure I did not move the compression nut at all.

A full replacement of the flax and rubber tube will go to the top of my offseason todo list, since I don't know when PO did it. Due to galvanic issues with the newfangled graphite flax on bronze shafts, I will use traditional wax flax.
 

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Today was our first chance to test out the stuffing box at full cruising speed.

We motored out for about 20 minutes, then I went down below to inspect. I didn't see any water dripping into the sump, but there was some liquid attached to the shaft and filling up the crevice between the nut and the shaft, so I know some water was getting in. I shot the temperature with the laser gun, and it came up at 72F. So it seemed like we were fine. We shut down the motor and went sailing.

On the way back in, I did the same thing after motoring for about 20 minutes. When I went down below, there was a nice, appropriately sized pool of water in the sump. But the shaft and nut were completely dry, with no dripping. I shot the temperature on the nut, and it was 110F (which means the flax inside was even hotter).

I'm trying to figure out what went wrong. It seems like we had water flow, cooling, and lubrication for awhile, but at a certain point it stopped and started heating up. Is it possible that once things heated up, the flax expanded from the heat, which caused even more friction and heating?

Obviously I need to re-adjust the stuffing box again, but I'm a little concerned that loosening the nut even a couple degrees of twist starts the water dripping when it's at rest.

Suggestions?
 

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When you were done did you test the temperature when the shaft was turning or off?

If off maybe the heat just built up in the minute or two it took you to get in position.

I don't know anything just thinking.

You seem to have an easy way to adjust so maybe another round of adjustment is all it needs.

I read the mainsail article and he mentioned that the shaft log can get bubbles that will prevent the drip. The solution is to allow it to drip more. It may even drip a tiny bit at rest if the shaft is not perfect.

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I generally don't like rules-of-thumb for drip rates and really hesitated to even put one on here. My reason for this is that every shaft has differing levels of wear and thus the drip rates are usually different in every installation.

The best rule of thumb I've found over the years is the least amount of drips when the shaft is spinning but before the box develops any heat. Again, it's a drip to heat ratio and little to no heat is the most desirable. Traditional flax packing can drip as little as about 5-10 drops a minute if adjusted correctly, while running, and this drip rate allows lubrication of the shaft.

Do not make adjustments to the packing nut, with traditional flax, for at least 24 to 48 hours as the plant based flax packing will absorb moisture and swell. This swelling can cause overheating of the stuffing box, if it is adjusted to quickly after launch and the swelling has not been accounted for

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The non-contact laser temperatures were taken while the shaft was turning.

After I got the boat into the slip and motor shut down, I went down an immediately checked the temperature by both touch and with the laser probe. It was still 110F, just like when it was running.
 

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I had to google it but I found a recommendation suggesting 30 degree's over ambient water temp is the expected temp range.

That seems about consistent with my touch tests, but maybe I let mine drip to aggressively at first. I have had to tighten mine on occasion.

It sound's like you may want to give yours a 1/4 to 1/2 turn looser and check again.

Assuming my internet sourced value of 30 above ambient is valid, does anyone know at what point immediate damage would begin? 110 degrees doesn't seem super high all things considered and assuming it is not continuing to rise.
 
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