Correct size packing for stuffing box?

[jim01749]

We have a 2008 Hunter 45 CC and was looking for correct size and maybe some tips on how to install new packing seal for the stuffing box?

Thanks
Jim

 

[Terry Cox]

Good morning, Jim. A hooked dental pic works pretty well getting the old stuff out. I use 3/16" PTFE material on ours. One ring at a time. Alternate each ring cut. Apply anti-seize compound to the box threads before reassembly.

 

[jim01749]

Hi Terry,

Thanks for the quick response. I was not sure if it should be 3/16" or 1/4". How do you know?

See attachment of the one I was considering.

Thanks
Jim

 

[shemandr]

Compass Marine has a comprehensive video on this. Well worth the time to watch if you are going to do this.

 

[dkinzer]

3/16" or 1/4". How do you know?

You can calculate the size by taking two measurements: the diameter of the prop shaft and the diameter of the threads behind the packing nut. Subtracting those two and dividing by two will give you the packing size. You probably should use calipers for these measurements. It's a good idea to have a set of 0-6" digital, dial or vernier calipers aboard for various precision measuring tasks.

Our 41AC has a 1-1/4" prop shaft and uses 1/4" packing. To be sure, buy both sizes and return the one that you don't use afterward.

 

[ggrizzard]

And, DO watch the video!

 

[Terry Cox]

How do you know?

You're welcome, Jim. Effort! Our boat has the standard bronze stuffing box with a 1-1/4" prop shaft. No way can I get 1/4" into that box unless I hammered it in. I've been using 3/16" for years (seven to ten years) with good results and even tempted to go with 1/8" because of how difficult it was to install 3/16". Your picture appears to be of the same product that I use. Low friction, good seal, lasts for years.

 

[jdrutten]

Don't forget to check your manual which likely has the packing size specified.

However, I've heard wild rumors on this very forum that for less leakage you might be able to get by with slightly oversized packing as long as it's well lubricated using the aforementioned PTFE or GTU/GFO packing and maybe a little SYNTEF lubricant for good measure.

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