MT34 Dual Cabin Shaft Log Replacement

[JoshW]

Well I've endeavoured to replace the failing/leaking shaft log on my Marine Trader 34. The constant leaking in this area has bothered me since I obtained the boat a couple of years ago. I began by cutting an access hole in the floor of the aft head shower pan and enlarged the hatch under the aft cabin companionway steps.

 

[JoshW]

What I found was the expected delaminated fiberglass tabbing the floor tie/stuffing box thart frame. I found the casting for the stuffing box was thru bolted and every bolt was spinning in the rotted floor tie. I attacked this with a combination of Fein saw and chisel and hammer to get the floor tie and delaminated fiberglass removed. It was immeaditly visible that I in fact had a hole in the shaft log. At this point it appears that the hole is caused by having the engine/shaft alignment too high causing the shaft to wear a slot in the shaft log.

 

[JoshW]

At this point I'm contemplating a temporary repair by cutting back and sleaving the shaft log with a bronze tube machined to appropriate dimensions. I had to expose more of the shaft log to cut it back and make sleave. What I found is more pitting and holes. So decision to pull shaft log is reality now.

 

[JoshW]

To pull the shaft log I removed the stearn bearing hanger bolts. Then inserted pry bars between the stearn bearing flange and the aft face of the keel. I dont know at this point how this is assembled. I found the stearn bearing housing was threaded onto the aft end of the shaft log. I managed to get it pulled aft about an inch with pry bars. I then ran a come-a-long from the stearn bearing housing to a tree that was behind the boat. I would apply pressure with the come-a-long and then persuade with a large hammer.

I am forgetting to mention that I had the boat hauled for the winter and have already removed rudder and prop shaft prior to this. I was replacing the swim platform due to an unfortunate accident last fall involving a storm, broken dock lines and a bulkhead. That is another large project, probably due a different thread.

 

[Larry M]

What a project. Thanks for posting.

 

[FoxtrotCharlie]

Quite a project! What year was your boat built?

 

[JoshW]

Built in 1974

 

[ARoss]

Josh, you have my sympathy. I’m a former owner of a 1973 MT34 and went thru the same exercise a few years back. Very frustrating since the first yard that worked on it really didn’t solve the problem and it took a second visit to a more qualified yard to fix it. They wound up putting in a fiberglass replacement shaft log. It was a project well beyond my capabilities, but good wishes for your successful solution of the problem.

 

[siestakey]

Thanks for sharing what a job!!!!

 

[Irish Rambler]

I don't envy you your task but in my humble opinion its not a job to be skimped and the only standard on such a critical part of your boat is perfection.
Near enough is not good enough.
Depending on your pocket and the rest of the installation would a 7degree down angle gearbox be a worthwhile proposition to prevent a re-occurrence and lower the engine profile ?

 

[Comodave]

Good luck with your project. Looks like you have a handle on it.

 

[geoleo]

My 1982 MT DC under previous owner had shaft log FG tube actually come loose ! In 2014 he had it repaired/replaced in Beufort SC Yard at a cost of $6400! He was enroute from Maine to South Florida.

 

[MVDarlin]

I don't envy you your task but in my humble opinion its not a job to be skimped and the only standard on such a critical part of your boat is perfection.
Near enough is not good enough.
Depending on your pocket and the rest of the installation would a 7degree down angle gearbox be a worthwhile proposition to prevent a re-occurrence and lower the engine profile ?

Tough sledding. I had to replace my 2" stainless shafts on my 43 OA many years ago because boat had not been run in a year (prior owner). Packing could not seal because shaft pitting at only that location would eat the packing in a few hours. $20,000 repair in 2004 +/-

 

[MVDarlin]

I don't envy you your task but in my humble opinion its not a job to be skimped and the only standard on such a critical part of your boat is perfection.
Near enough is not good enough.
Depending on your pocket and the rest of the installation would a 7degree down angle gearbox be a worthwhile proposition to prevent a re-occurrence and lower the engine profile ?

Might be a good time to add tangible coupling. Only a few hundred $$$. Could save a tranny/engine.

 

[SeaMoose]

I went through this on my 76 MT 34 about six years ago now, I had help it’s a huge job by oneself, very impressive. What was your keel filled with? Mine was full of river gravel, under the aft cabin sole is concrete.

 

[MVDarlin]

I went through this on my 76 MT 34 about six years ago now, I had help it’s a huge job by oneself, very impressive. What was your keel filled with? Mine was full of river gravel, under the aft cabin sole is concrete.

"frangible shaft coupling" sacrificial, it will shear and save your tranny/ engine if your prop hits something.

 

[JoshW]

I went through this on my 76 MT 34 about six years ago now, I had help it’s a huge job by oneself, very impressive. What was your keel filled with? Mine was full of river gravel, under the aft cabin sole is concrete.

I found both areas filled with a concrete gravel mixture. The top 1" in the keel area had fallen apart probably due to age and leaking seawater constantly keeping it wet . I chiseled out all that was loose and have filled with thickened epoxy and have begun the fiberglass repairs.

 

[JoshW]

"frangible shaft coupling" sacrificial, it will shear and save your tranny/ engine if your prop hits something.

Thanks for the suggestion, what brand of coupling would you suggest? Seems like this would be a good improvement with everything disassembled.

 

[JoshW]

I don't envy you your task but in my humble opinion its not a job to be skimped and the only standard on such a critical part of your boat is perfection.
Near enough is not good enough.
Depending on your pocket and the rest of the installation would a 7degree down angle gearbox be a worthwhile proposition to prevent a re-occurrence and lower the engine profile ?

Thank you for the insight, unfortunatly I rebuilt the engine bedding and the Paragon gear only a couple years ago. I do intend to do the best I am able and not skimp on any part of the new shaft log installation. I will be posting progress pictures along the way.

 

[SeaMoose]

Thanks Josh. My issue was the aft coupling, which we rebedded. Left the gravel in there, filled the small void with foam building up a cloth plug to close the hole fwd of the coupling we made.

 

[JoshW]

Update, received the replacement shaft log tubing from the machine shop that threaded one end to match the metric threads in the stern bearing casting.

 

[JoshW]

More progress pictures. New shaft log install completed. Now to start putting everything else back together that was removed for this task.

 

[SeaMoose]

Looks really good Josh, nice work.

 

[alormaria]

Schweeet!

 

[RT Firefly]

 

[Larry M]

That’s the same boat? Nice job!

 

[88FuHwa]

This entire posting was quite timely for me and the boat yard where I had to take it to repair a small leak that was filling up the keel. It turned out to be a leaking shaft chute that was embedded in the fiber glassed member that mounts the stuffing box. The boat yard manager reviewed this posting and after yanking out the SS chute, which was severely corroded, also recommended a fiberglass replacement.
That work is being done as I speak at considerable expense but I had no choice and the boat yard is fortunately quite professional and credible. I surmise that most Taiwan Tubs will eventually run into this repair so, be prepared for a hefty charge and a long time on the hard. I will post the details once the job is complete.

 

[Memorymaker]

Shaft log replacement

Does anyone have any information or knowledge on how to replace the shaft log that the driveshaft slides through replacement

 

[88FuHwa]

Yes, the yard finally decided that a fiberglass option was not the best and reinstalled a stainless steel tunnel. It meant boring out the entrance to the keel and installing a new stuffing box. All had to be fiberglassed in and aligned with the transmission. Quite elaborate and I could not have done it myself. Very costly as well but I had little choice. Yard rates are $120 per hour in the SF Bay Area so you can imagine the bill when it was done.

 

[Comodave]

Yes, the yard finally decided that a fiberglass option was not the best and reinstalled a stainless steel tunnel. It meant boring out the entrance to the keel and installing a new stuffing box. All had to be fiberglassed in and aligned with the transmission. Quite elaborate and I could not have done it myself. Very costly as well but I had little choice. Yard rates are $120 per hour in the SF Bay Area so you can imagine the bill when it was done.

Bet you didn’t sit down for quite a while after getting that bill... Amazing how it adds up.