Non-standard stern tube and cutlass bearing

[sailorchic34]

So the Rose has a non-standard stern tube (Oh $%^& Joy). Most stern tubes are made from pipe where the inside diameter is the pipe size. The Stern tube on the Rose is actually 1-1/2" stainless steel Tube. Which means the exterior is 1-1/2 inches diameter and the inside is 1.414". Compounding that is my prop shaft is 1-1/8" diameter. Not a lot of space for a cutlass bearing.

Back in 2009 I replaced the old plastic cutlass bearing that was beyond shot. I purchased a 1-1/2" x 1 bronze cutlass bearing and had the outside turned down to 1.41. I then attacked the inside with a brake hone to get it to 1-1/8".

In another year I will be hauling again. I suspect I might need to address the cutlass bearing at that time. I would like a better way then spending $250 (bearing plus machining).

Any thoughts from the collective on the best way to do this. The old cutlass bearing was plastic, perhaps nylon, perhaps machined to fit, but I have been unable to fine a suitable replacement.

What's a Girl to do????

[a64pilot]

Anything I can think of, which is replacing the tube is more painful than living with what you have.
At least you are now aware of it.

[Celestialsailor]

We're close and I have a machine shop. If you wanted a plastic one, I could machine one up for you. You would have to wait until early summer for me to get back from Mananaland. The better thing to do is replace the stern tube with a F/G one of standard sizes. If you laminate, you could do it yourself. A yard would want a Kings ransom to do it.

[Pete7]

SC, disappointed that our last cutlass bearing didn't last very long I found an interesting thread on an owners forum. It would appear that all cutlass bearings are not made equal. The Vetus brass ones have a molded inside rubber piece whilst the more expensive ones are first moulded over size and then ground back to spec. £45 for a 1.5 x 4" expensive cutlass against £25 for the Vetus one. I hope the more expensive one therefore lasts longer due to the cost of lifting. Also there are two types of "rubber" for the inside bit. One is much harder and therefore likely to last longer.

Your 1 x 1.5 doesn't sound very long to support the shaft, can you fit a longer one?

[bletso]

Vigah has a similar non-standard OD on the Cutlass bearing. I had to have ours turned down as well. I had toyed with the idea of turning out the ID of the cast bronze housing but decided, (from engineering advice), that it may not have held up. The housing screwed onto the shaft log and the bolted to prevent turning. Of course it took a while trying to figure out how to remove it after we removed the bolts. Engine / Power Train | Sailing Vessel Vigah I replaced mine with a Duramax purchased from Humco Marine Products, St. Louis. Duramax can also custom manufacture your bearing if you want. Contact is Glenn LaMarche glenn@humcomarine.com

The pics are the housing. Good luck

[foufou]

Why do both the stern tube side and cutlass bearing side of the cutlass bearing side of the housing have to be the same diameter? If the housing has a diameter that accepts a standard cutlass bearing on one end and a diameter that accepts a standard tube diameter then the problem is solved isn't it? By the way, Mc Master Carr sells G-10 tubes with standard OD. In my case I bought a 1.25" OD G-10 to replace a 1.25" stainless tube.

[bsurvey]

look into stave cutless bearings that you can fit with the shaft in place

[UNCIVILIZED]

I'm wondering if starting with a piece of G-10 tubing might be the way to go. Whether you have to machine it a bit, & or, add an insert to it. Though as stated by others, 1" sounds too short for such a bearing. And may be why it's wearing so quickly. How many engine hours between bearings? And are any of the other shaft support bearings or structures wearing so rapidly?

[sy_gilana]

Sailorchic, you will love this site....

Vesconite STERN TUBEÂ* Design-a-Bearing Calculator IMPERIAL

Or just browse around, they have a LOT of stock.
I can vouch for their product, slurry pumps in mines are a tough design challenge.

[Cheechako]

Originally Posted by Pete7

SC, disappointed that our last cutlass bearing didn't last very long I found an interesting thread on an owners forum. It would appear that all cutlass bearings are not made equal. The Vetus brass ones have a molded inside rubber piece whilst the more expensive ones are first moulded over size and then ground back to spec. £45 for a 1.5 x 4" expensive cutlass against £25 for the Vetus one. I hope the more expensive one therefore lasts longer due to the cost of lifting. Also there are two types of "rubber" for the inside bit. One is much harder and therefore likely to last longer.

Your 1 x 1.5 doesn't sound very long to support the shaft, can you fit a longer one?

I suspect she's talking 1.5 OD and 1 ID before machining to fit. Not length....?
SC: yeah, not much to work with there with the tight distance between ID and OD on your stern tube. That doesn't leave a lot of rubber in there! You could put in a proper fiberglass stern tube but that's a lot of work for sure. How many hours since 2009? Seems like it shouldn't be worn out already....
Incidentally, I think all my stern tubes have been fiberglass....

[sailorchic34]

Yes the cutlass length is 4-1/2" long. I have to cut a 1-1/2" OD brass x 1" ID rubber down from 1.5. to 1.414 and then hone most of the rubber out from 1" to 1.125. That was sooo much fun.

I'm pondering going with a 1" prop shaft rather then a 1-1/8". But then I need a new prop, etc and that's starts to get spendy The yanmar only has 24 ish hp peak and I never run at peak anyway. That would mean I only need to have the outer bronze cut down. That leaves enough bronze to tap in.

I suspect that someone either ordered the wrong material tube rather then pipe or was shiped the wrong one 45 years ago. There is not that much boaton either side of it either. Removing the old stern tube sounds like a ton of work.

Yes Vesconite is an option. I found a Chinese site that might be able to machine one too. I'll probably chat with them boat and see about having two made.

Hours since 2009, probably 800 hours ish or so. Mind you there was all of a 1/16" of rubber left once the prop shaft fit. So it's most likely bronze on SS now.. .Joy. The shaft is actually worn a few thousands where the old bearing was so there was a bit of space for water to lube it..

I kind of want to be ready with a new cutlass bearing once I haul if it's found to be bad. Last time it took 8 days to find a bearing that would work, have it machined down, etc,etc. All on the hard of course. So much fun back then.

But I have over a year before that happens again. Really April, May ish 2018 would be as soon as I might have enough funds for a haulout. Of course staying in fresh water during summer months helps keep the hard growth down.

CS. A plastic bearing would work too. No rush on that as I'm more then a year away from needing it. I just want to have something in my hand before I haul next time. bearing OD is 1.414 (ingrained in my memory), ID is 1.125. x 4.5 long with a few tiny slots for water. I can hone it, if it's a tad tight. I'll probably be in the delta being a layabout good for nothing this summer anyway. Let me know costs. But no rush.

Ya'll can imagine my surprise when I learned that the Roses stern tube was a non-standard size and that off the shelf was not going to happen. Of course I found that out AFTER removing / trashing the old plastic bearing that had a wee bit O play in it anyway. Was nearly 1/16" OUCH...

[sailorchic34]

BTW, the total prop shaft length is 48" end to end exactly.. Distance to front of prop from back end of hull is 1/2". All numbers pulled from my old mind and firmer ingrained. So its a fairly short prop shaft. Engine supports the front end with standard screw packing gland.

On the plus side I have a V drive so shaft pulls out from the inside. Which is nice as I have an aperture prop area that is a bit tight and would have needed to drop the rudder or pull the engine to remove the prop shaft otherwise..

[Celestialsailor]

Well...you could go to the 1" shaft and use a tapered bushing. People tell me that they work fine and I believe you can buy them at "Bay Ship" (who now owns Svendsens).
I would be happy to turn the (1.5" to 1.414" (ingrained) on my Toolroom lathe. Like I said, I will be back in April to build my friends dodger and back to Mx in Jan 18 prepping for the Marquesas. If all goes well.

[a64pilot]

I think with that little of rubber, I'd go with a plastic housed bearing, that way if it wears, it's SS against plastic, not bronze

[sailorchic34]

I just had a crazy Idea.. OK I have many I know.

1-1/4" CPVC tube, available everywhere has a 1.125 ID (exactly what I need) and 1.375 OD. If I add 0.02 ss shim stock (available from granger) around a 6" long section of cpvc tube it works out to a 1.415 od again just about perfect.

I could even get a slightly thinner shim stock and epoxy it to the CPVC (maybe not sure how well it would stick). So for about $30 in parts I could make about 5-6 cutlass bearings. I would need to hacksaw cut some short water grooves in the tube.

CPVC is 7500 psi tensile strength compared to nylons 10,000 psi. CPVC has same compression strength to nylon. Pretty sure the old bearing was Nylon.

I could roll my own plastic cutlass bearing for not too much money.

Please tell me why this would not work???