stern tube replacement

[The Good Goose]

The stern tube in my triton consists of two different sized tubes one inside the other. The one for the cutlass bearing is, I think, 1and 7/8 inch inside diameter. Inside of this is another tube for the stuffing box that is outside diameter around 1and 1/2 inch.
Unfortuanately these two tubes are not in alignment. I replaced my cutlass bearing last year and was unable to get the shaft to align with the engine properly there wasn't enough movement in the mounts. However when I attached the stuffing box I could align the engine perfectly. I think the old half a bearing was short enough that it could move in the shaft log and line up ok. I used a longer bearing and I Think it had no play so the misalignment of the two tubes showed up. I used the engine very little last year because of this; sailing almost exclusively.

I need to either re mount the engine or replace the stern tubes. My questions are as follows:

1 I'm leaning twoards replacing the stern tube do you think this is the best option?


2. Is there any reason to use the double tube arrangement or should I just use one diameter of tube?

3. Where is the best source for fiberglass tubes and what should I be looking for; ie type of glass thickness etc?

4. After I drill the old tube out with a slightly oversized hole saw I'm thinking I'll set the new tube in thickened epoxy . I'm thinking I'll use the shaft and the cutlass bearing to line it up. I'll set the engine in the middle of it's mount adjustments, apply thickened epoxy to the hole , slide the tube over the shaft and set the cutlass bearing. Is this a good method or is there a better way?

5. Is thickened epoxy enough or do I need to glass the protuding ends as well? If so with what type of cloth etc.?

6. I think the new cutlass bearing is ok so I would like to reuse it. Is there any advantage to using a different diameter tube that would outweigh the cost of the bearing?

7. Why in the world haven't I installed an access hatch in my cockpit?:)
I think I still have scars on my arms from last year.


Thanks in advance for any help I'm sure appreciative of the advice here.

Brock Richardson

[bcooke]

7. Why in the world haven't I installed an access hatch in my cockpit?:)

<sigh>

[Figment]

4. After I drill the old tube out with a slightly oversized hole saw I'm thinking I'll set the new tube in thickened epoxy . I'm thinking I'll use the shaft and the cutlass bearing to line it up. I'll set the engine in the middle of it's mount adjustments, apply thickened epoxy to the hole , slide the tube over the shaft and set the cutlass bearing. Is this a good method or is there a better way?

5. Is thickened epoxy enough or do I need to glass the protuding ends as well? If so with what type of cloth etc.?

6. I think the new cutlass bearing is ok so I would like to reuse it. Is there any advantage to using a different diameter tube that would outweigh the cost of the bearing?

Hey Brock,

If the inner tube aligns with the engine, I wouldn't mess with it. Just remove/relocate the outer tube.

#4 is how I "align" the Atomic-4, which has almost zero adjustability to its mounts. Works for me.
#6, I think a new cutless bearing is about $12.

[Tim]

Removing an old and installing a new stern tube is quite straightforward, assuming you have reasonable access. (hint: new cockpit hatch!)

Check out this article for some ideas. I wouldn't mess around with saving anything--just cut out the old and epoxy in the new using this method (or a similar method).

One advantage of the new tube is that you can align the tube to the engine as you epoxy it in, giving excellent initial accuracy that will help with all future engine alignments. Your diesel probably has better overall adjustibility than the fixed A4 mounts, but being able to align the tube to the engine is very helpful and I recommend it.

The double-tube arrangement, I think, was only something used to help with installation. There are no practical reasons to go that route.

Unless you have trouble sourcing a new tube of the proper diameters to accommodate your existing bearing and stuffing box, there's no reason to go new since your bearing is so new, unless there is already wear on it.

[Rachel]

I think a new cutless bearing is about $12.

Mine retailed for about $50 at Hamilton (it was either the Duramax "Acid" or "Apex," I forget now). Not that saving one is a reason to go with one particular set-up over another; I'm just showing how out-of-date you are.

;^)

R.

[Figment]

I was being mildly facetious, but still they're pretty cheap as boat-parts go.

(the Duramax ones are even cheaper)

[Rachel]

Huh. That is quite a bit cheaper than Hamilton (I was referring to a Duramax, which I bought). Oh well, I like shopping there, so no matter in this case.

R.

[The Good Goose]

Tim
I don't know why I didn't see that article earlier. I usually follow your projects pretty closely. I like the idea of the stuffing box to align rather then the cutlass bearing as I was planning. Where is the best source for sterntube material? and what should I be looking for?

Thanks everyone for the help.

Brock

[Tim]

I used prefab fiberglass tube from McMaster-Carr--1-1/2" outer diameter (1-1/4" ID). I'm sure there are other sources for fiberglass tubes too, but this stuff is inexpensive and consistent in quality and availability.

An afterthought: the stepped tube size of the original Triton stern tube means that you may have trouble reusing all your components (stuffing box and Cutless bearing) with a single tube, since the old inner tube is of smaller outside diameter than the old outer tube. I'd suggest that if necessary, it makes more sense to resize the stuffing box or Cutless bearing to fit the tube rather than step the tube sizes, but that's a decision best left to the individual.

Depending on the hose size of your stuffing box, and the OD of your Cutless bearing, you may find you need to make changes to one or the other in order to fit the tube.

[The Good Goose]

I had thought about the stuffing box having to be replaced already. I think a larger one might be better anyhow. Not having the two stern tubes seems less complicated and worth the price of a new stuffing box.
who makes a good stuffing box? Where are they available?

Thanks Brock

[Rachel]

Buck Algonquin sells them - either separately or as a package with a length of their specific stuffing box hose. I believe Hamilton Marine has them, among others.

[The Good Goose]

Thanks Rachel
I never heard of Buck Agonquin but I like the name. I had a hard time finding stuffing box hose and ended up using exhaust hose with a steel wire in it last time so I'll try them.

Brock

[The Good Goose]

I am running into a snag in this project. My shaft is 7/8" and the only stuffing box I can find for 7/8" shaft is the Buck Algonquin model. It uses 1 and 3/4" hose. Mcmaster Carr has tubing in 2" and 1and 1/2" OD sizes .

Does anyone Know of another stuffing box for a 7/8" shaft?

Failing that I can Machine down the tubing to 1 and 3/4" on one end. This will leave 1/8" thick fiberglass where the stuffing box hose attaches. Is this strong enough?If not I guess I can get a length of 1 and 1/2" OD pipe and glue it inside in that area. Do you think this would be neccessary?

Any thoughts, ideas or sources of tubing or stuffing boxes of the right would be appreciated.

Thanks
Brock

[Figment]

It may be easier to wrap the end of the 1-1/2" tube up to 1-3/4". I had to do that with my existing Triton tube in order to mate it with the stuffing box hose.

(PO had used very compressible hose and honked down on the clamp instead. That's right... "clamp". singular.)

But wait, I think I missed something. Why are you replacing your existing stuffing box?

[Tim]

Don't reduce the thickness of the fiberglass tubing; that would make it too weak. You're better off trying to wrap it with fiberglass to increase its thickness appropriately. Since you're starting with a new tube, it should be fairly straightforward to wrap fiberglass cleanly and evenly around the inside end as needed. Do yourself a favor and allow the new tube to extend further into the inside of the boat than the original, as it will improve clearance and clamping space for your new hose. (Assuming you have room between the coupling and stern tube to allow for more exposed tube, that is.)

I had a similar issue myself, years ago. My prop shop, who sourced my stuffing box for me, machined a 3/4" stuffing box assembly to accommodate my 7/8" shaft, allowing me to use the 1-1/2" hose size to match my stern tube size.

[Tim]

I never know the status of Spartan Marine, and what they actually stock, whether they actually want to sell anything, or whether they are really still kicking, but if they are up and running they show a wider variety of fiberglass tubing in their catalog, including 1-3/4" OD tubing (with either a 1-1/4" ID or 1-3/8" ID).

Link: Fiberglass Tubing at Spartan Marine

[Peter]

I am running into a snag in this project. My shaft is 7/8" and the only stuffing box I can find for 7/8" shaft is the Buck Algonquin model. It uses 1 and 3/4" hose.

I don't know if this helps, and I know it's not the best solution, but on the Vega I have a 1 1/4" OD shaft tube and a 1 1/2" stuffing box. The local marine supply had special rubber inserts to step up the shaft tube size to fit the stuffing box hose. I had to use 2 to get the sizes to match ... used a little gasket sealer (flexible) at all the joints and double-clamped the works ... no leaks and very solid.


Edited to add a picture of the installed bushings:

[The Good Goose]

But wait, I think I missed something. Why are you replacing your existing stuffing box?[/quote]
My thinking was to use a 2" stern tube and reuse the cutlass bearing and replace the stuffing box. I think my new plan is to use 1 and 3/4 " tube, if Spartan marine will ship and actually has it, and replace the cutlass bearing.
Plan C is to use 1 and 1/2 inch tube and wrap the end for the existing box and a new cutlass bearing.

This all goes to prove the saying:"Nothing is ever easy".

Thanks Brock