1 Topic by john_co26 (edited by john_co26 2012-05-05 15:54:55)

  • Registered: 2009-07-25
  • Posts: 112

Topic: How was your luanch, and source for a prop shaft? lessons learned.

Hello all

So I suspect this is a big weekend for boat launching, so how has it gone? For me? Not so good.

Before I get into my sorry (and long winded) tale does anyone know of a Canadian source for prop shafts and cutlass bearings? I pulled the shaft today to replace the stern tube and am not sure if  I want to use both in re-assembly or replace them.

Over the last several seasons my stuffing box has started to drip more water than I like so I decided to re-pack it, about a week ago. Yesterday I went down to the boat to do a final inspection before launch day(today) I took one final look at the stuffing box, rotating the shaft(by hand) checking for play/stiffness. To my surprise the stern tube(the rubber hose connecting the stuffing box assembly to the cutlass bearing assembly) was rotating slightly with the shaft. Not a lot, but worse, I noticed that the wire that is imbedded into the hose was rising to the surface as  I rotated the shaft. After 20 minutes of rotating the shaft back and forth the wire broke free of the hose. Not good, a day before launch. Given the amount of effort it took to get it out of the boat I probably would have been ok for the season but no way was I launching as things were. I need to sleep at night.

I keep my boat at Portsmouth Olympic Harbour in Kingston, and launch day is a 3 day affair using a rental crane, if you don't get in this weekend you are on your own, crane wise. I spent yesterday trying to remove the flange from the prop shaft with no luck, today went much better. The shaft and stern tube is out of the boat but re-assembling before end of day tomorrow is not going to happen.

Not the end of the world as I had planned on keeping the boat out next summer to do a partial refit/over-haul. So that will be happening this summer instead.

Lessons learned
- Re-pack my stuffing box a week after the end of the season not a week before the beginning of a new season.
- Pay closer attention to all hoses on-board. I did inspect the stern tube prior to re-packing the stuffing box and all looked well. I think that as I dis-assembled the stuffing box I loaded up the hose exposing an underlying problem with the hose.
- Removing the flange from the engine side of the shaft. It doesn't matter how many times you hit it with a punch and a hammer, its not coming off. To remove it, I removed the rubber drive coupling(correct terminology?? correct me please) from the transmission and pulled the shaft back as far as I could. That gave me enough space to attach a gear puller to the flange and off it came.
- In my case, a two bladed prop, I didn't have to remove the rudder from the boat to pull the shaft, with the rudder pulled to one side I had enough clearance to pull the shaft.
- For what it is worth, I needed to use 1/4 stuffing not 3/16's or 5/16's. I have read here and else where that 3/16's thru to 5/16's is correct for the co26.

So, not the end of the world, better to find the problem a day before launch than a day after. I could still make the season if  I wanted to tow the boat to Collins Bay Harbour across town(my boat sits on a trailer and they have a crane on site at all times) I have decided to accept things as they are and get on with fixing some of the problems I have, this year rather that next year. I am looking forward to it, working on the boat is almost as much fun as sailing it, for me at least. So I will be back with more questions I am sure, for now I hope your launch goes better than mine.

Fair winds,
John

  • Registered: 2006-09-20
  • Posts: 175

Re: How was your luanch, and source for a prop shaft? lessons learned.

What's wrong with the existing shaft?

There was the year that the engine and shaft were still sitting on a  pallet beside the boat the day before the launch date while I finished rebuilding the shaft log . . .

I did get it all back in place and watertight by the end of the day's craning (I had arranged to go last) but I was still applying the antifouling grease to the prop as the tractor drove up. :-)   We sat alongside on the crane berth over the weekend while I finished stuff off and *JUST* finished hooking up hoses and wiring + alignment in time to get off the berth before the yard bought the first booked "lift & scrub" boat round.

Put a month in doing maintenance in decent weather then see if its worth launching for a shortened season . . .

  • Registered: 2009-07-25
  • Posts: 112

Re: How was your luanch, and source for a prop shaft? lessons learned.

Ian

You are better at working with tight time lines than I am smile

I have several concerns about the existing shaft, but I am not sure if they are warranted;

- The shaft does have some wear at the point where the flax rubs against it, not a lot but some.
- More importantly. the shaft is a press fit on the flange,  there are two grub screws, one to hold the key in the slot the second to help hold the shaft to the flange. With that said it is my understanding that it is the press fit that holds the shaft to the flange,  the grub screws are secondary. Generally speaking a press fit is a one time affair, you lose holding power if you re-press the shaft to the flange.

So putting aside the wear in the shaft, am I cutting corners by trying to re-use the shaft and flange? I don't have an answer to this so at this point I am trying to get as much info as I can.

Any and all options welcome,
John

  • From: Ottawa, On
  • Registered: 2005-03-10
  • Posts: 353

Re: How was your luanch, and source for a prop shaft? lessons learned.

you might want to look at replacing the stufffing box with a volvo penta "packing box"  i dont have the part number offhand, i posted it here some ways back.  no flax, no drips.  just pull the shaft every year  (if youre particular like me) and grease the bearing surface and seal lips, then burp it once its in the water.  then you can have a dry bilge....

the prop shaft shouldnt really be press fit in the flange, the hold down screws are what keep everything together.  usually rust on the inside of the bore in the flange is what makes it so hard to separate flange from propshaft,  i always install with some copper antiseize.

if the propshaft isnt scored, i would polish it up and reuse

im with ian on that one, work on it for a bit and not at a panic pace.  be ready in a few weeks and wait it out till someone else is launching or being hauled partway thru the season.  the best months in the 1000 islands are from aug till mid oct....

stefan_d's Website

  • Registered: 2009-07-25
  • Posts: 112

Re: How was your luanch, and source for a prop shaft? lessons learned.

Stefan/Ian

Thanks for the replies and confirmation on what I am learning relative to my prop shaft. I dropped by a prop/marine repair business today and they basically said the same as  the both of you. Re-use the shaft as is, after cleaning it up.  Which is what I will do. I am looking into a dripless packing box, no decisions yet.
As to dropping in several weeks from now; it is tempting, I don't want to miss a season. With that said the boat does need some work and taking the season to deal with some/all of the problems is something I don't want to put off any longer. The list of things is not all that long but will take some time;
- repair soft cores in the deck
- rebed all deck hardware
- paint the deck
- add 3'rd pintle/grudgeon
- repair existing pintle/grudgeons(to much play for my liking)
- remove old transducer/boat speed propeller and glass over the holes in the hull.
- replace at least two sea-cock/gate valves
- etc

Most of these could be addressed one season at a time, with that said  the idea of keeping the boat out and plugging away at the above list makes sense to me. I will probably feel differently the first windy and warm day I spend on shore smile Between my former life as a windsurfer and now keel boat sailor, this will be the first season off the water since I was 16 years old sad


I will be back with questions relative to the above to do list.

Thanks,
John

6 Reply by Ian Malcolm (edited by Ian Malcolm 2012-05-11 21:50:59)

  • Registered: 2006-09-20
  • Posts: 175

Re: How was your luanch, and source for a prop shaft? lessons learned.

  • From: Barrie, Ontario, Canada
  • Registered: 2005-10-10
  • Posts: 237

Re: How was your luanch, and source for a prop shaft? lessons learned.

If I recall correctly, (from 10+ years ago) the guys at Holland Marine told me that the rubber hose connecting the stuffing box assembly to the cutlass bearing assembly should not be the usual black hose with the wire in it. Since it is subject to movement and vibration, the wire will eventually wear the surrounding rubber and come to the surface. They sold an identical looking hose specifically for that purpose that did not have the wire. They also stocked the cutlass bearing.

  • Registered: 2009-07-25
  • Posts: 112

Re: How was your luanch, and source for a prop shaft? lessons learned.

Hello all

Things are progressing and stalling out at the same time.

One the positive side I was able to remove the old cutlass bearing and press in the new one, no problems.

On the down side I have a problem. The stern tube has a larger dia than the stuffing box tube. Both have lip that is larger than  the tube size. The stern tube is 1 5/8's dia with an 1 3/4's lip. The stuffing box tube is 1 1/2 dia with a 1 5/8's lip. This can't be normal can it?? I have no reason to think that this is not the original setup, with that said how to deal with this? My local supplier can get 1 3/4 stern tube hose which fits nicely over the stern tube but would be a loose fit on the stuffing box end. He can't get 1 5/8's stuffing box hose. Even if he could, getting it to fit over the stern tube would be tough given it's stiffness.

Thoughts?


seeadler  thanks for the heads up on holland marine, I will be contacting them to discuss my situation..

John

  • Registered: 2006-09-20
  • Posts: 175

Re: How was your luanch, and source for a prop shaft? lessons learned.

Photos of your stern tube and stuffing box showing the lip please - some modifications may be required!

The first option would be to stretch a ring of inner tube rubber over the stuffing box end to pack it out a bit. You will need to use a water based rubber lubricant during assembly so the hose doesn't displace the rubber tube.  Do this off the boat so you can easily check the rubber is still in the right place.

Get the best quality hose clips you can and put a turn of insulating tape under them to protect the hose surface from abrasion and you will be amazed how well the hose compresses onto a slightly undersize fitting.

Other options - if you can get 1 5/8" hose, would be to modify the stern tube to reduce (but not totally remove) the lip.

10 Reply by stefan_d (edited by stefan_d 2012-05-13 06:12:19)

  • From: Ottawa, On
  • Registered: 2005-03-10
  • Posts: 353

Re: How was your luanch, and source for a prop shaft? lessons learned.

stefan_d's Website

  • Registered: 2009-07-25
  • Posts: 112

Re: How was your luanch, and source for a prop shaft? lessons learned.

12 Reply by Ian Malcolm (edited by Ian Malcolm 2012-05-14 02:03:17)

  • Registered: 2006-09-20
  • Posts: 175

Re: How was your luanch, and source for a prop shaft? lessons learned.

Is the stern tube also bronze?

I suppose I am fortunate to have an 'old-skool' rigidly mounted stuffing box and a stern tube threaded at both ends to mate with the stuffing box and the cutlass bearing housing which are also bolted to the surrounding GRP so they cannot rotate.   Of course this makes engine alignment a real PITA as  I have to get five points in a straight line - both ends of the engine, the mid-shaft support bearing (needed to stop engine vibration and resulting shaft whip beating up the stuffing box packing) and both ends of the stern tube.   When I was rebuilding it all I ended up having to make a jig with a Laser beam for alignment as taut fishing line got in the way too much.!

  • Registered: 2009-07-25
  • Posts: 112

Re: How was your luanch, and source for a prop shaft? lessons learned.

14 Reply by Ian Malcolm (edited by Ian Malcolm 2012-05-15 02:07:04)

  • Registered: 2006-09-20
  • Posts: 175

Re: How was your luanch, and source for a prop shaft? lessons learned.

I am not sure about your stuffing box, but mine has an integral white metal bearing in it that keeps the shaft centred so the packing can do its job.  Replacing this bearing is expensive and difficult as very few machine shops still have any experience or capability to pour Babbet bearings.   It was actually cheaper to have an off the shelf replacement body casting, including bearing machined for an exact fit than to refurbish the old one.  Money was saved by reusing the packing nut, though I had a new locking nut made as the old one showed evidence of having been tightened/loosened by an idiot with a hammer and cold chisel.   I now have spanners to fit.

After 20 years, if your box has a bearing, it's probably knackered so replacement is worth it for peace of mind alone . . .

If you cant get the right size box shipped to you, if I were you, I'd look for a shop that reconditions bronze propellers.  All you need is someone who can build up   braze >1/16" all the way round and machine to profile leaving you with a 1/8" increase in diameter.

Another DIY option is to build it up with glass tape and epoxy to match the stern tube diameter, carefully constructing a new lip. Some care is required to get a nice dense layup with a smooth surface.  Copper alloys *MUST* be bright and freshly sanded for epoxy to bond,  and ideally you should sand mixed resin into the pores of the metal surface, wipe off as much as possible then continue with a normal layup.

This is not rocket science - just make sure that whatever you do is sound, but no need to gold-plate it

N.B. DO NOT be tempted to build up any critical pipe nipple with normal self-amalgamating tape.  Its too soft and squeezes out of the joint + turns into a goo if any diesel fuel gets on it.  It could easily turn a minor fuel weep into a sinking . . .