Catalina 30 Engine Replacement: Prop Shaft Alignment and Stuffing Box

[RUSSELL]

I set the MMI replacement engine in my 1978 C30 three weeks ago and was hauled for the season. I have not had an opportunity to do much since - no work on the boat, just reading a few posts here. I hope to get some pictures of the engine compartment and new engine up soon.

So, it seems like one of the first things to do is get the prop shaft back in and get things aligned. I was surprised to see little mention of this process in the prop/drive train discussion topic. If anyone has any sources then I would appreciate being pointed in that direction. I'd like to understand all I can prior to beginning that task.

I also have a question related to the stuffing box. I will replace the stuffing box hose and clamps. The question really deals with packing. It seems to me there are three approaches:

(1) Traditional flax packing: the idea is to keep a flow of water out but let enough water seep by when the prop shaft is turning to lubricate and cool the shaft. It seems to me it is tricky to get the packing box nut tightened just right so that she drips a little when the prop shaft is turning but is dry otherwise. It seems to me this is the lowest cost alternative, and is tried and true over decades of use.

(2) High-tech packing material: similar idea, but is made out of different materials that allow adjustment of the packing box nut so that no water seeps in - lubricates the prop shaft enough so that turns easily and does not get hot. Here is an example from the CatalinaDirect supply firm:

http://www.catalinadirect.com/index.cfm?fuseaction=product.display&product_ID=1352&ParentCat=391

This approach seems to cost somewhat more but does not appear to be terribly expensive. Has the advantage of not letting water in the boat.

(3) The dripless stuffing box. I don't quite undertsand how this works. Here is one example:

http://www.shaftseal.com/en/categories

This is clearly the most costly way to go.


Has experience shown that one of these is clearly the best approach? Are the advantages and disadvantages well understood?



I have to add that this forum is great. I learn more here in ten minutes than weeks of conversation around the dock. I don't think I would have ever started working on my boat without forums like this.

Thanks.

[sastanley]

Hi RUSSELL,

I had to do just that procedure (new shaft/align,etc.) last summer in a Catalina 30. The thread is titled "Indigo", and started with a new prop & ended with me replacing everything aft of the motor. It is a long thread, but like you, something I would have never tried to accomplish without the help from fellow forum members.

I am using goretex ($15 from West Marine) packing in a traditional stuffing box. I don't even get enough water in mine to sponge out the bilge..it evaporates before it gets there. Those dripless (PSS or similar) things are great, but if the bellows fail, the boat sinks. I also don't really like that green stuff from CD..the goretex is so close to dry that I would not bother with other stuff.

http://www.moyermarine.com/forums/showthread.php?t=4044

[ndutton]

Alignment
Since you are hauled I recommend initial alignment with the stuffing box and hose removed. Shim the shaft so it's centered in the inboard end of the shaft log (fiberglass tube sticking in the hull. with the coupler on the shaft adjust the engine position so the gap between the coupler and engine output shaft is equal at four cardinal points, tolerance within 0.003" is the accepted standard.

Up and down adjustment is achieved with the adjustment nuts on the engine mounts and you will have to loosen the mounts in the engine stringers to nudge the engine sideways.

Install the stuffing box after alignment is complete and recheck after launching.


Stuffing box
You have traditional flax down pat, I can't contribute more.

Gore packing isn't drip free by any means and runs hotter, frighteningly hotter in the experience of a very knowledgeable C-30 neighbor of mine. He wound up using 2 rings instead of three and letting it drip to manage the heat. Note also that the same size of different brands differ slightly in dimension. That stuff can drive you nuts.

Dripless shaft seals like the LasDrop and other variants have their own issues. In a perfect world they work great but any debris or scratches between the sealing surfaces and they don't seal at all. And contrary to the glossy sales brochure, they are not dripless but more accurately they drip, just less.

They also have to be occasionally purged of air. Some have addressed this issue with a vent tube that has to be run from the seal body to a point well above the waterline when heeled hard over.

I built a boat in the 80's and considered a LasDrop. I sought out the best information I could find by contacting the production manager for Islander Yachts. At the time Islander made a 34 with a V drive and an inaccessible shaft exit below the engine so they used a LasDrop seal as standard equipment. He told me they had so many problems (the scratch and debris issues mentioned earlier) that he'd never install one in a boat again unless forced to with a gun to his head.

This is another area with differing opinions and mine certainly aren't the last word.

[hanleyclifford]

Good discussion. Neil. Best to go with the traditional flax packing. The trick is to start out loose (less than hand tight with new material)and work it in to one drop every four seconds.

[ILikeRust]

I repacked my stuffing box, and also found, next to the packing stuff, a small tube of "grease" that seems to be mostly lanolin, or something similar, which purports to help the packing remain watertight but run cooler by providing a little lubrication.

Dunno how well any of it works yet, as the boat is still on the hard (a condition I really hope to rectify within the next couple weeks), but I have no reason to believe it won't work fine.

And I don't think it should be too "tricky" to get the packing tightened just right. If it drips too much, crank it just a little bit tighter until it doesn't. If it doesn't drip at all, make it just a little bit looser until it does. Once you get the right drip rate, tighten the lock nut.

It is "tricky" only to the extent access to the stuffing box and lock nut is awkward - as it is on my boat...

[edwardc]

... Gore packing isn't drip free by any means and runs hotter, frighteningly hotter in the experience of a very knowledgeable C-30 neighbor of mine. He wound up using 2 rings instead of three and letting it drip to manage the heat. Note also that the same size of different brands differ slightly in dimension. That stuff can drive you nuts. ...

When I redid my stuffing box this past spring, I used 2 rings of the Graph-Tex (like GoreTex but with graphite fibers) surrounding a "ring" of Pacific Trading Company's moldable dripless packing (the green goo).

Initially, it too ran frighteningly hot (200 degrees and rising after a minute!). What I discovered was that, although it seemed to fit properly, the 1/4" packing size I used was one size too big. The correct 3/16" packing looked laughably undersized, but sealed right up with just loose finger tightening of the packing nut. And it runs cool, only 10 to 15 degrees above the ambient water temperature, with no drips.

After about 50 hrs of run time, it settled in a little and began to drip slightly. A slight adjustment of the packing nut stopped the drip, and it continues to run cool and drip-free.

[Dave Neptune]

Go Gore~no chads (flax)

Russell, go with the Gore!! I went to it a number of years ago and love it. Yes it did run a "bit" warmer for a bit but after a few hours it began to run much cooler. I re-adjusted it a few times and again the next year. Now I have not touched it for about 3 years and it's still holding fine. Cold I get about 1 drop every 40 seconds or so~about a "cup" full every 2~3 weeks. Note I have a 3/4" shaft and run the Indigo at 1800~2200 shaft RPM's.
The trouble with the flax is not getting it to hot the first try and having all the "waxie" stuff run out of the packing.

Dave Neptune

[ndutton]

I have to add that this forum is great. I learn more here in ten minutes than weeks of conversation around the dock. I don't think I would have ever started working on my boat without forums like this.

Thanks.

I couldn't let that comment pass unnoticed. Nicely said.

[thatch]

"Killer's Row"

Russell,
Between Bill, Dave, Ed, Hanley, Neil and Shawn, (alphabetically) you have been given, as usual excellent advice. Shawn's "Indigo" thread is absolutely worth taking the time to read. Being about the same vintage Catalina 30 as your's, makes it all the better. If there was one thing that I could add, it would be to recommend that you stay with the old style stuffing box rather than one of the newer "dripless" types of seals. Many people swear by them but, despite having an almost perfectly aligned A4 in my '78 Catalina 30 and after repeatedly checking the friction surfaces for scratches and for proper bellows adjustment, my PSS seal leaks far more than any stuffing box I have ever used.
Tom

[msauntry]

I went with the PSS and couldn't be happier. I lived with the stuffing box for years and didn't find it to be bothersome, but I have good access to that area compared to some. Both work fine. If drips bug you, go PSS. I don't think new boats even come with stuffing boxes anymore.

[tenders]

I've had both the stuffing box (5 years) and Lasdrop shaft seal (replaced once in 15 years), and the next time I have to disassemble that part of the boat I'm going back to the stuffing box.

The stuffing box gets the job done with the smaller number of parts and a high degree of fault tolerance. The flax can be replaced with the boat in the water and without removing the shaft from the coupling.

The shaft seal gets the job done with more parts that are harder to replace, and a possibility of a severe problem if the bellows or the smoothness of the faces of the seal degrades or is interrupted by junk in the water. Replacing the seal or any of the parts requires removing the shaft from the coupling, and almost certainly hauling out.

I might feel differently if I had an easy-to-access shaft, but I don't. My v-drive sits on top of the shaft and access is very limited.

[ndutton]

All good points and Micah's experience although in the minority is good information too.

Isn't it interesting though that the original design of the stuffing box was so good there have been virtually no significant improvements in 95 years. Kinda hard to argue with a history of solid performance.

[tartansailboat]

Neil, just a question about your comment on the initial alignment procedure. I assume that the cutless bearing is in place so that I don't see the need to shim the prop shaft to be concentric with the shaft log. I would think that the cutless bearing is sufficient to center the prop shaft. What am I missing here?

[ndutton]

Supporting a 50" bronze or monel (heavy) shaft by 4" at the end with a rubber bearing will certainly result in sag at the unsupported end. Plus, we've seen second hand what a shaft not centered in the log can do (see the epic 'Indigo" thread - Shawn saw it first hand). It's reasonable to believe the log and bearing were properly aligned by the manufacturer so starting with the shaft in the original position (in the bearing and centered in the log) is in my opinion the place to begin a full alignment exercise as Russell is doing having replaced his entire engine.

The full keel guys don't have quite the issue we fin keelers do with our bearing in a strut and the shaft log a different and distant component.

[hanleyclifford]

Following the procedure Neil outlined it is a good idea to examine the cutless bearing closely to see how the shaft has been/will be running in the cutless. Look for uneven wear at both ends of the cutless which will give you an idea of how the shaft has run in the past. If you put in a new cutless make sure the "centered in the log" position also yields the "centered in the cutless" position. If there is a variance favor the cutless rather than the log, within reason of course.