Packing Leakage Management

[JDubya]

I think I'm having to adjust my packing more often than I should. I tighten the packing gland just enough to stop dripping while moored, and then verify that I'm getting a good drip rate while underway. However, when I return to the pier, the leaking continues once the shaft is stopped, until I tighten it up again.

I purchased a used 2021 C-30S in September and have six underways under my belt since delivery. My arrangement is NOT a "traditional" stuffing box/nut + locking nut (like the arrangement depicted in the "Spring Maintenance Pt 1" episode of the As the Prop Turns webinar series). What I have is a twin-stud arrangement on the packing gland to compress the packing in the stuffing box. Each stud has two nuts, I'm attempting using the outer nut as a "locking nut" once I've tightened the gland with the inner nut. I've tried to be very careful to ensure that I'm tightening each side equally to avoid any misalignment of the gland in the stuffing box.

I've found lots of videos online about how to repack this type of stuffing box, and lots of discussions about desired packing drip rates while moored vs. drip rate with the shaft turning. I haven't found any specific discussions or videos demonstrating proper methods for adjusting this type of configuration. I'm surprised at having to make adjustments every time I moor, and what I'm finding online indicates that I shouldn't need to be adjusting this much.

One interim solution I'm considering is to replace the two nuts on each stud with a single nylock locking nut. If all that's going on is that the nuts are backing off from vibration, this might solve the issue -- but if I've got a bigger issue then this solution may not really solve my problem.

Any thoughts from the community here are greatly appreciated.

 

[GaylesFaerie]

While having no drips at the dock with engine off and cold is ideal, my R27 will leak maybe 2 drips a minute with the engine cold and off. I've found that to be no problem especially since I regularly rinse my bilge with fresh water. What is your drip rate at the dock that has you concerned? Gary

 

[JDubya]

I've been between 15-30 drips per minute dockside, enough to put a noticeable amount of water in the bilge over the course of 3-4 days.

This is after adjusting for zero, seeing no drip rate develop while moored for a week or more, and then getting one drip every 2-3 seconds at about 1500 rpm while underway. If the drip rate remained low (~2/min like what you're seeing) when I get home, I'd probably be much less concerned.

I think overall I'm just trying to get a better sense for "normal" behavior, while erring on the side of more leakage so as to avoid inadvertently scoring the shaft.

 

[SJI Sailor]

On our C30S (2019) it was impossible for me to get it adjusted in any lasting way when new. I eventually gave up and had it repacked by CSR when other work. That was a couple of years ago ... and it's been perfect since then, maybe a single 1/8 turn adjustment since then, if I recall correctly.

One thing the factory said to me at a Rendezvous is that it doesn't really need to drip much even when underway. Only enough to stay not-too-hot (they suggested no hotter than a cup of tea you could hold). Ours stays like that with very little dripping (none when docked).

 

[JDubya]

Thanks, that's a good perspective. I may be in a similar fight with mine until the first time I haul out. She's still < 100 engine hours so I'm still early on.

Maybe I'll give it a couple of extra flats on the next adjustment, and then keep a closer eye on the stern tube temps.

 

[BB marine]

There is a simple procedure and rule to adjusting packing. Only adjust in small increments. If you see waxy residue flung on the gel coat in the bilge the packing was probably tightened to much and got hot. Once you advance the packing pusher or nut there is no backing up. The packing gland used on the 30 is easy to over tighten. Once over tightened and heated it may have destroyed the packing. If it was not over tightened here is the advise I would give. Secure the boat well to a dock. Start the engine and put it in forward gear. Count the drips. You want to see no more than 3 drips a minute. If you see several drip in a minute. Shut the engine down and adjust the packing by turning the two nuts no more than a half a flat. Recheck repeating the in gear inspection. If you see a reduction in drips but still more than 3 drips in a minute you may be ok. Adjust it again a half flat. Repeat again in gear inspection. The drips should be less. If so keep repeating this until you achieve the 3 drips a minute. Patience is needed when adjusting packing. Going for it all on one adjustment usually results in over tightening and then you are chasing it all the time. Normally when you are chasing it the best way to resolve it is to start over with new packing and make small adjustments. Properly adjusted packing used in water cooled glands should last 1000 hours and normally require one or two adjustments in that 1000 hours. Packing and Cutlass bearings normally require replacement at the same time if packing adjustments are done properly and water flow to the cutlass bearing is maintained. If the boat was commissioned properly, packing adjustment and engine alignment checks done by the dealer when the boat was commissioned you should not be touching the packing. My guess is the factory or commissioning dealer over tightened the packing gland from the start and you are already chasing it. If I was a betting man I would put odds on the the same thing happened to SJI Sailor. I would argue the factory about there temperature range of packing. My estimate of temperature is about 5 to 10 degrees warmer that the water cooling it. Grab the water line going to the gland then compare the temperature of it to the gland temperature. It should be very close to the same. If it is warmer by more that 5 to 10 degrees the packing is too tight. When the gland is adjusted properly it should not leak at all when the engine is not running.

 

[gswearin]

Hi Brian,
Just wanting to confirm my understanding of your excellent post. I have a 2021 R29 and have been "chasing" the gland since I got it, thinking it was a routine thing. Is your advice if we are chasing the drips them should go ahead and repack? Or only if the glans is 5-10 degrees warmer?
Thanks!!

 

[sgeary]

At about 500 hours on a D4-300, I was not able to get my packing adjusted properly. Each time I made an adjustment and then used the boat, it would once again drip excessively when the engine was stopped.
I replaced the packing material and still had the same problem.
I then had the shaft alignment checked and it was way off.
After correcting the alignment, I was able to get the proper drip rate and went another 175 hours without an additional adjustment.

 

[JDubya]

Thanks for those replies, Brian & sgeary.

I'm definitely trying to be very judicious in my adjustments, no more than necessary to just stop the drip when moored, but I'm also getting more than 3 drops/minute when I lift the hatch to look at it underway. I'll have to try the adjustments by the pier, but I'm becoming more concerned that 1) this packing is indeed shot and 2) I should also have the alignment checked to be sure I don't have that issue contributing to the problem.

 

[BB marine]

Hi Brian,
Just wanting to confirm my understanding of your excellent post. I have a 2021 R29 and have been "chasing" the gland since I got it, thinking it was a routine thing. Is your advice if we are chasing the drips them should go ahead and repack? Or only if the glans is 5-10 degrees warmer?
Thanks!!

The temperature of the gland is a check after adjusting the packing. If you do small increment adjustments and walk it in to 3 or less drips a minute while in gear. the temperature will not be an issue. If the adjustment is made by you or a technician and then you see elevated packing gland temperatures you know you over tightened it.

At about 500 hours on a D4-300, I was not able to get my packing adjusted properly. Each time I made an adjustment and then used the boat, it would once again drip excessively when the engine was stopped.
I replaced the packing material and still had the same problem.
I then had the shaft alignment checked and it was way off.
After correcting the alignment, I was able to get the proper drip rate and went another 175 hours without an additional adjustment.

Normally when a boat is commissioned the alignment and packing adjustments are done. If done properly there should be no issues that we are talking about here. THE ONLY REASON THAT THE ALIENMENT SHOULD SHIFT IS IF MOUNTING BOLTS COME LOOSE. Mounting hardware does come loose. The Rangers and Cutwaters are built with wood in the stringers and lag bolts hold the engine mounts into this wood. They do come loose. They need to be inspected. When I took delivery of my C26 Cutwater I did not trust the dealers delivery process. I actually did not have a Pre-delivery inspection from a Volvo certified technician and did it myself. I did find 1 lag bolt not only loose but stripped out. I found the engine out of alignment and when aligned properly part of the mount was hanging off the engine stringer. I posted pictures of this.
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I did a packing adjustment after alignment as part of my inspection. I did a complete check sheet and sent it to a Volvo dealer and they sent it in to Volvo for me. I did not have a packing issue or a dripping gland until 300 + hours. I made one adjustment of a 1/2 flat and then. I made an adjustment when I sold the boat with 650 hours. The total adjustment at this point was 1 flat of a turn or a 1/4 turn of the nut.

You should not have to chase the packing. Alignment and proper adjusting is key. Be patient when adjusting. The gland on the C30 is a bit harder to adjust than the single nut glands. The C30 can easily be over tightened. Be Patient!!

 

[JDubya]

Another thought/question on this: what are the risks of operating with mis-alignment? I’m wondering what else I may need to be sure is checked once I can get my alignment checked, if it is found to be out of line. I’ve put about 20 hours on the engine myself at this point.

I assume this could put uneven stress and wear on the cutless bearing, or even lead to significant shaft or perhaps engine damage.