CD36 stern tube

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Russell
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Joined: Feb 5th, '05, 11:14
Location: s/v Lady PaulineCape Dory 36 #117

CD36 stern tube

Post by Russell »

Well I just finished removing my prop, stuffing box and stern tube. The stern tube arrangement is just plain silly I think. In order to get the rubber hose off the thing I had to remove the whole thing from the boat since the clamps were hidden in the hull. The rubber was in very bad shape, so I am glad I took it out and could see it. Now reclamping it isnt possible with this stern tube, CD used some odd clamps that didnt have screws, so it could fit, not somehting I can get here, and not sure if I would want them anyways.

What I am thinkinig is somehow lengthening the stern tube so I can clamp a new (shorter) hose onto the tube and still be able to access it from inside the boat, ussing regular hose clamps. I would love opinions on this, I am no metalurgist, I am going to a machine shop tommorow to talk to someone, but bronze isnt something often used down here, how well would some sort of welded on bronze peice work? I worry about strength, if this thing broke it would be a serious problem.

Russell
Russell
s/v (yet to be named) Tayana 42CC
s/v Lady Pauline Cape Dory 36 #117 (for sale)
Oswego John
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Location: '66 Typhoon "Grace", Hull # 42, Schooner "Ontario", CD 85D Hull #1

Stern Tube

Post by Oswego John »

Russell,

Ask the shop if they have any high tensile brazing rod in stock. Possibly even stronger, silver solder.

Good luck,
O J
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David van den Burgh
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Location: Ariel CD36, 1979 - Lake Michigan
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Pictures

Post by David van den Burgh »

Russell,

What a great opportunity to get some pictures of the process and the steps involved! I don't suppose you have a camera on hand to snap a few? I'd love to see what you're up to.

Good luck, and I look forward to reading about your progress.
Ron M.
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Location: CD30c Harwich,Ma.

Post by Ron M. »

Russell,
If you are replacing your shaftlog go ahead and install one that is longer, that will make maintenance and inspection easier. I know of a couple CD owners who have.
I'm not keen on welding pieces together but given your location that may be your alternative, unless you can fabricate another fiberglass one. Good luck
________
M112 Engine
Last edited by Ron M. on Feb 11th, '11, 05:34, edited 1 time in total.
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Russell
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Location: s/v Lady PaulineCape Dory 36 #117

Post by Russell »

OJ, thanks for the tip on the brazing rod, I will ask about that.

David, I can certainly snap some photos, its an ugly mess right now, not the kind of thing I like to share, but it could certainly be of some use to other CD36 owners who one day may face the same problem.

To give some background on this whole thing: I hauled out to paint the bottom, while enroute to the yard I heard some odd noises and vibrations that were seperate from the engine noise. It had to be coming from the drive train somewhere, my instinct was the cutless bearing.

Once the boat was out, I grabbed the prop shaft and with all my might pushed it back and forth to see if it was loose. It was solid and the yard mechanic agreed, he didnt think the cutless bearing was a problem.

The yard guys cleaned all the growth and barnicals off the bottom and the prop, etc. once off I started looking closely at everything. It didnt look right. There was no zinc, but I had been hanging a zinc grouper overboard so I wasnt expecting electrolosys... but sure enough, I had it, and bad. Simply picking with my thumbnail at the metal on the end of the shaft where the nuts screw on I was actually able to get some of the metal to flake off! Scary stuff! The prop however looks totally fine, as do the thruhulls, seems the bronze prop shaft has a higher zinc content then everything else(my theory) so acted as a sacrafical. So the shaft had to come out, and what a job that was...

To get it out we had to cut it in half, 3 hours of banging couldnt get the coupling off, no problem since its being replacing anyways. Taking a good look at the shaft once out, I am lucky I made it here.

My theory is this issue predates my ownership of the boat, its simply way too bad to have happened in a short period, this is years of issues here. They just reared their ugly head after the shaft had muratic acid brushed on it to clean the barnicles.

Oh and just another fun thing about repairing a boat in the caribbean, the local chandlery does sell prop shafts (shipped in from St. Martin) but the shortest one they sell is 6 feet!! So I had to buy a 6' shaft to cut down to replace my little 18" or so shaft. Though I figure I can easily sell the excess.

Back to the stern tube issue, I wonder if anyone with a Robinhood 36' could desribe their setup? I cant imagine its the same as the mid 80s CD36, which is downright silly, I hope they improved it. I know the older CD36 (from reading archives) has a longer bronze stern tube which the stuffing box attached directly to, with no rubber. I can see how adding the rubber was considered an improvement, but not the way they ended up doing it. If robinhood did improve on it, perhaps they have a ready to go solution I could just buy from them? Granted its for a different engine and transmission so the angle would probably be wrong or something anyways.
Russell
s/v (yet to be named) Tayana 42CC
s/v Lady Pauline Cape Dory 36 #117 (for sale)
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Russell
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Location: s/v Lady PaulineCape Dory 36 #117

Post by Russell »

Ron Musk wrote:Russell,
If you are replacing your shaftlog go ahead and install one that is longer, that will make maintenance and inspection easier. I know of a couple CD owners who have.
I'm not keen on welding pieces together but given your location that may be your alternative, unless you can fabricate another fiberglass one. Good luck
Ron, the CD36 doesnt have a fibreglass sterntube, I know from reading archives that most other models do though. Its just a short bronze one, problem being its so short that the clamps are inaccessable and litterally in the hull(which is insanely thick here) The welding issue has me concerned as well, but they certainly dont do bronze casting here to make me a new one, so extending with a weld may be the only options, but what would they use? Bronze house plumbing pipe? I have serious concerns about having this work done here, but its completely nessisary work, I have no choice.
Russell
s/v (yet to be named) Tayana 42CC
s/v Lady Pauline Cape Dory 36 #117 (for sale)
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Jim Davis
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Edgewater, MD

One possibility

Post by Jim Davis »

Go to McMaster Carr http://www.mcmaster.com/ then search for "pipe nipples", go to "brass pipe nipples" and "threaded both ends". Scroll down to "cast red brass" I think you will find what you need. Red Brass is what seems to be normally sold as bronze today.

Good luck.

p.s. My wife owns the open Ty you saw at Caso Rio.
Jim Davis
S/V Isa Lei
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Al Levesque
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Location: Athena CD33 #94 Salem MA

Post by Al Levesque »

Some while ago, maybe 6 or 8 years ago, we had our shaft replaced in an out-of-town yard. The yard mechanic said he couldn't clamp onto the tube and had an extension welded on. I didn't question it and just hoped he had a qualified welder do it. We have had no trouble with it. Two years ago the tube came out for some other work and it looked fine.

Bronze seems to weld readily, I think it is actually brazed, and I have never felt any qualms about the strength. The loading is not great anyway. The extra length makes future work much easier and I wonder that Cape Dory didn't give us the extra length in the original. The extra length also allows installing the dripless shaft seal.
Greg Kozlowski
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Joined: Jun 1st, '06, 08:29

Some advice on stern tube

Post by Greg Kozlowski »

Hi Russell,

Find a good welder down there who knows bronze well. As you know, our 1979 model 36 has a one piece combination stuffing box-stern tube. After we bought the boat, I discovered that the thread on the stuffing box was shot. I pulled the stern tube and took it to a guy who knew bronze. He cut off the stuffing box threaded end and welded on a new one I had bought. The two mated perfectly. Extending the length of the stern tube in a similar fashion might be your best solution at the moment.

Good luck,

Greg
Gregg
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Location: CD 36 # 10 LaBaleine San Mateo, Ca

Post by Gregg »

Russell & all,

My CD 36 is '78 and I thought I would contribute to this thread with the set up I have and follow this work to learn & appreciate what you are doing. I first question how you removed the stern tube?

As with Greg, my set-up is without a hose. The shaft enters the bronze 1 1/2" dia stern tube with a packing nut where it enters. The tube is threaded to accept the packing nut. Aft is a lock nut and aft of this the tube is directly embedded in the hull. I will email you pictures. I have absolutely no room to extend the tube (as Greg described) since the packing nut is only 1 1/2" aft of the coupling nut.

In preparing to repack the box, I question what a longitudinal cross section of the tube looks like and how it is held in the hull Is it cast bronze, are there ridges on it or in it? Is there an internal ridge to which the packing material compresses?

Best of luck & thanks for your advise in the past, Gregg
Gregg Johnson
Greg Kozlowski
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Joined: Jun 1st, '06, 08:29

solid stern tube

Post by Greg Kozlowski »

Hi Gregg,

I can answer a couple of your questions.

1. The tube is thru-bolted by two bolts to the hull. You can see the nuts on the bolts above and below where the bolts enter the hull.

2. The stuffing box takes three rolls of 1/4 inch stuffing and it compresses against the threaded end of the stern tube.

Be carefull when threading the nut on after putting in new stuffing. It is very easy to screw up the thread on the tube end, and if you do that, you will have to pull the stern tube and repair it as I did.
Suggest you put in two rolls, screw them in tight, then unscrew the box and put in the third roll.... it should be easier that way
Gregg
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Joined: Feb 9th, '07, 12:42
Location: CD 36 # 10 LaBaleine San Mateo, Ca

Stern Tube & Stuffing Box

Post by Gregg »

Greg,

thanks for the descriptions. After my post I found a great drawing by the pervious owner showing a longitudinal xsection through the stuffing box, and notes about the 3 ea.1/4" packing rings as well as some custom devices to assist in the process. I would imagine that it will be a tight fit getting the rings on the shaft with the limited room available when the nut is backed off. How much sea water should I expect or is this strictly a job at time of haul? And yes I would agree that the threads need to be treated with great care.

In your description of the stern tube being bolted, and visible above & below, is this from inside or out? I do not see any sign of such from inside.

Regards, Gregg
Gregg Johnson
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Russell
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Location: s/v Lady PaulineCape Dory 36 #117

Post by Russell »

Hi Gregg,

I got the picture you emailed me a few days ago of your arrangement. Definately different from mine, certainly probably what Greg has though.

Its shocking to see how much bedding compound they used on yours, assuming thats what that is, it seems to extend pretty far up the tube beyond the hull, thats going to be a real bitch to remove if you ever have to.

As for the bolting your asking Greg about. Its visible inside and out. Inside, in the photo you sent me, the top bolt is clearly visible above the stern tube, this is how mine (and I assume all CD36s are). Its the bolt you see the bonding wires attached too. The bottom bolt is not visible, but its certainly there, and a HUGE pain in the ass to get to. Your going to want a deep socket of the right size handy when you need to remove it, and of course someone on the outside to actually turn the bolt with a big screwdriver (and perhaps impact driver at first, dont strip it though!).

Your shaft appears stainless, thats suprising, perhaps its been replaced at some point? Or did early CD36s have SS shafts? My 84 was bronze.

Dont take this wrong, but glad to see someone elses engine sump looks as nasty as mine does!
Russell
s/v (yet to be named) Tayana 42CC
s/v Lady Pauline Cape Dory 36 #117 (for sale)
Gregg
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Joined: Feb 9th, '07, 12:42
Location: CD 36 # 10 LaBaleine San Mateo, Ca

Post by Gregg »

Russell, It just looks nasty.

Is the tube a casting? do you have photos so that I can see how nasty it really is?

Let us know how you will proceed.

Gregg
Gregg Johnson
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vjasinski
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Post by vjasinski »

Russell
I believe we have the same setup on our CD33. We recently had to change the hose between the stern tube and the stuffing box. I found that the clamps used be CD can be found and clamped by a hydraulic parts supplier. The clamps are called "preformed clamps." The layout on the CD33 is such that we could not lengthen the stern tube as you are contemplating. All back together for us, and we are now in the Bahamas.
Vince
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