# Prop shaft strut repair



## jfdubu (Jul 18, 2002)

Ok guys, I have quite a repair ahead of me. Without posting on the PO thread it's apparent that the PO wrapped a line around the prop and bent the strut. I just bought the boat and yes the survey reveled this problem. The strut is bonded into the hull and does not have a flange.
My three choices for the repair are;
1) buy a new "close fitting" strut from Bock Algonguin, $ 600.+
2) cut existing strut out and weld/braze on a flange (bronze)
3) fab a new strut out of stainless

I have access to a full on machine shop and can do most of the work myself, zero boat $

All three options involve cutting the existing strut out and realigning the whole drive train. When I think of the things I can buy w/$600 options 2,3 are my preferred methods. So the question becomes what's wrong with fabbing a new strut out of stainless and/or would the welding/brazed method be strong enough?

John


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## deniseO30 (Nov 27, 2006)

what boat, size, engine and shaft size may help those trying to help you.... Many struts are "glassed in" so the flange isn't showing. Often, the fuel tank is over the "bump" where the strut would be located in the back bilge area. even the bolt "bumps" show on some boats. 
Don't know how you found a new one at such a high price.. unless it's a very large boat.


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## overbored (Oct 8, 2010)

Stainless is not good below the waterline. why do you need a flange. there are struts that are straight on the end and are glassed into the boat. the glass in one are cheaper


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## jfdubu (Jul 18, 2002)

The boat is an express 35, yanmar 3gm, 27hp, 1" shaft. The strut is a straight tang glassed in. It's loose at the hull join and leaks, neither of which is acceptable.
I could cut it all out and start fresh but I really don't want that "hole" in the boat.
Once I do start cutting my plans may change. I have great access to both sides of the hull. Nothing in the way on the inside. 
The price was as quoted by Buck Algongin. I was shocked too, and the part does not really fit. More mod's would take place.


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## Markwesti (Jan 1, 2013)

Ditto on no SS below water .


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## SchockT (May 21, 2012)

If I am understanding you correctly the strut is bent, AND it's fibreglass bond to the hull is broken. If that is the case then you will need to grind away the damaged glass and remove the strut. From there you can assess how badly bent it is, but there is a good chance you can straighten it with a hydraulic press while it is off the boat. Then it is just a case of reinstalling it the same way the manufacturer did, and glassing it in again. There is a reason they use bronze instead of stainless, and there is a reason they glass it into the hull. Why try to reengineer the boat?


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## deniseO30 (Nov 27, 2006)

jfdubu said:


> The boat is an express 35, yanmar 3gm, 27hp, 1" shaft. The strut is a straight tang glassed in. It's loose at the hull join and leaks, neither of which is acceptable.
> I could cut it all out and start fresh but I really don't want that "hole" in the boat.
> Once I do start cutting my plans may change. I have great access to both sides of the hull. Nothing in the way on the inside.
> The price was as quoted by Buck Algongin. I was shocked too, and the part does not really fit. More mod's would take place.


You still have to dig out the old one. Very very good chance you will find a flange in there. I've seen this done a few times by DIY friends in my YC. with all due respect you are over thinking this project. Pulling the prop will maybe be the most difficult part of the job.

I know you don't want to do a "repair" that looks like this.


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## StormBay (Sep 30, 2010)

At $600 for "close" it may be better to have a new one cast. Thats what we just did. It came out to be closer to $700 with a new bearing included but ours is massive and weighs 50+ lbs (so at $4 a lb, thats $200 in bronze alone)


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## Faster (Sep 13, 2005)

This is a pretty critical piece that you'll want to do more than 'make it work'.. and if you can get it done for under a boat buck that's relatively inexpensive peace of mind for the future. But it doesn't sound like your $600 'close enough' is the best plan either..


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## jfdubu (Jul 18, 2002)

To be clear, engineering things is what I do for a living, reengineering a boat is not a big deal. I'm not looking for the path of least resistance. This is a "I only want to fix this once" quest. Where my experience lacks is the strength of brazed bronze. There is a 6"x6"x8" box inside the hull that houses the broken strut-hull bond, no flange


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## deniseO30 (Nov 27, 2006)

John, I know I'm not the only one that would love to see photos of this mess! 

I guess from the builders way of thinking, a flange-less strut would be an easy install rather then mold a recess for the bolted and buried flange. No need to worry about shaft angle. just slide it on the shaft. and "glue it in place with resin! Betting they did the shaft log that way too.. after the engine and drive line were in place. It would save many hours on the build of a new boat. this is just speculation on my part.  

Just think, back in the day when they had to drill long holes through a solid wood (usually white oak or other very dense hardwood) "deadwood" to get the shaft in the keel of wooden boats being retrofitted with engines.


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## Capt Len (Oct 9, 2011)

The seal is broken and leaks so cut it out or what ever it takes , straighten it on a press and re glass. Bronze is quite easy to fix ,even with a larger mallet. Probably won't even need heat. A couple of large pipe wrenches can twist the shaft hole back to alignment. (don't need my bare foot augers much any more)


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## tommays (Sep 9, 2008)

1. I weld and braze a bit and do NOT know any naval bronze brazing rod ?? and it will most likely crack if you unbend it







2. It will be a plenty big challenge just getting it back in and lined up as they always do a poor job at the factory


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## JimsCAL (May 23, 2007)

Brazing is not the best way to go. I found a crack in my strut along the barrel where the set screws to hold the bearing in are. Contacted a former coworker who teaches welding and pipefitting. He recommended arc welding, not brazing. He came out to my boat with his portable machine and welded the crack. Has been fine for three seasons.


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## svHyLyte (Nov 13, 2008)

jfdubu said:


> The boat is an express 35, yanmar 3gm, 27hp, 1" shaft. The strut is a straight tang glassed in. It's loose at the hull join and leaks, neither of which is acceptable.
> I could cut it all out and start fresh but I really don't want that "hole" in the boat.
> Once I do start cutting my plans may change. I have great access to both sides of the hull. Nothing in the way on the inside.
> The price was as quoted by Buck Algongin. I was shocked too, and the part does not really fit. More mod's would take place.


The method of mounting of your J-Strut is not uncommon for boats of the mid-80's era. We have a similar arrangement on our boat and had to effect a similar repair. In many/most cases, the pocket that the strut slips into was built up of numerous layers of glass around a sacrificial foam mold that was dissolved after the glass cured. The strut was then slipped into the resulting "slot" and one or more pins were passed through the sides of the pocket and through holes in the strut. In some cases, transverse triangular gussets were also built into the sides of the pocket to prevent the strut pivoting from side to side about the "slot". Once aligned, the edges of the slot around the strut were dammed with caulking putty and the remaining cavity around the strut filled with thickened resin. Several layers of glass were than applied over the pocket and carried down to the hull to prevent leakage of any water that might infiltrate the pocket.

To effect the repair, you do not want to unduly damage the pocket. If you can grind the outer layers of glass down on either side you should be able to determine whether drift pins were used to position the strut as described above. If so, these can be driven out (with some effort) and the strut worked loose and slid out of the hull. With that, a good machine shop may be able to straighten the strut or, if not, fabricate a duplicate. The foregoing is somewhat more difficult to describe than to actually do although the effort is unpleasant (BTDT). Reinstalling the strut is not difficult and the alignments and positioning will be preserved provided the mounting pocket/box is not unnecessarily damaged during removal. Once the strut is repositioned, one dams the slot around the strut with caulking compound and injects thickened epoxy around it within the pocket through small holes pre-drilled in the pocket for that purpose. Once that's cured, a couple of layers of woven roving over the pocket finishes the job.

FWIW...


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## PBzeer (Nov 11, 2002)

I also had a bent strut that is glassed in over where it joins the hull. Had it fixed in a yard, where we pulled the strut, straightened it, then re-attached and glassed back in. Forget the exact cost, but other than the material to re-glass, it was all labor. (You may as well replace the cutlass bearing as well unless it is nearly new) Had no shaft alignment problems after the repair.


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## jfdubu (Jul 18, 2002)

I will take plenty of pre, during, and post pics. And I will be very careful in the initial removal phase. To make matters more interesting the PO install a new dripless shaft seal and motor mounts. Now everything is aligned to an out of position shaft. Stay Tuned.


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## jfdubu (Jul 18, 2002)

before pic's second attempt.,, foiled again


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## Faster (Sep 13, 2005)

jfd... SN pic upload is toast. Use Photobucket.com and paste the IMG code directly into the body of your text. Works much better.


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## jfdubu (Jul 18, 2002)

Well, I failed in my attempt to post the before pic's but I will try again. I'm well into the "during" phase of this project and it's not as bad as I expected. The strut isn't bent it and it didn't appear to be misaligned when I took it out. So the strut was just installed funny. New question what would considered too much shaft run out. I have .004 at the ends and .025 in the center. Doesn't seem too much to me.

John


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## JimsCAL (May 23, 2007)

jfdubu said:


> Well, I failed in my attempt to post the before pic's but I will try again. I'm well into the "during" phase of this project and it's not as bad as I expected. The strut isn't bent it and it didn't appear to be misaligned when I took it out. So the strut was just installed funny. New question what would considered too much shaft run out. I have .004 at the ends and .025 in the center. Doesn't seem too much to me.
> 
> John


Not sure I understand what you mean by "installed funny". Note that some boats (like my Cal 33) have the shaft off center to permit removal of the shaft without dropping the rudder. With regard to the shaft, I would just replace it.


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## jfdubu (Jul 18, 2002)

Installed funny as in it was canted about 4 degrees such that it looked like it was bent coming out of the hull. I'll get the pics posted and you can see it. 
BTW, I didn't start this project because of the "bent" look, I started it because It was loose and it was weeping water.

John
Ok two pics added. these are the before pics


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## jfdubu (Jul 18, 2002)

OK, I got pictures. The above post shows the before. In the outside pid you can see the strut canted. These are the "during" showing the box cut out and the strut removed. 
Hopefully next week will be the finished product.


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## tristan35 (Oct 30, 2016)

Reviving an old thread since I'm working through the same issue (although not quite as bad as this appeared to be)... 

My wife and I recently acquired an Express 35. I've been a little hard-pressed to find many other owners or much specific tuning/maintenance information about the boat online so I was interested to see that you (jfdubu) have (had?) one as well. 

Currently I'm seeing just a trickle of a leak when under motor and nothing noticeable under sail or at anchor. The fix for this season is going to be grind a small trough around the strut and fill with a flexible sealant, then fix a hole in the glass 'mound' inside the hull. If that doesn't hold this season, I'll be into a more involved fix next winter.

Just wondering how did your repair go in the end? Any 'after' pictures?

Best,
Tristan


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## Jack Smith (Sep 25, 2017)

tristan35, how timely! I hope my situation helps with yours. I just got my transit out as I will pull my Cal MK III this week. This boat came with a improper set strut due to a folding prop that blew apart. The strut was eyeballed in?! There is excessive vibration in the shaft. I plan on dropping the rudder, pulling the prop and shaft. I will check & true the shaft if need be. I believe after shooting the strut , log and drive line the strut will have to be cut out and reshot. Old salts advised of lag screws holding the strut plate onto the hull under the fiberglass. I plan on rematting with six10 and fibreglass, building up on both sides of the strut plate. Have faith in your ability. Can you really mess it up as bad as the "professionals" who reset mine originality. keep us posted. good luck. my pics will follow. thanks, JS


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## jfdubu (Jul 18, 2002)

Well, Funny how things happen. I haven't been on the site in a couple years. This morning I decided to check it out. Tristin, first great to hear someone else has one of these boats to compare notes with. I have hull 32 and have done a quite few repairs and upgrades. I have details of how my strut came out, it's rock solid and leak free. Lets compare notes

I sail out of Narragansett bay.

John


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## jfdubu (Jul 18, 2002)

Jack, It sounds like you have flange mount strut, if so you should have pretty good vertical reference to start. I'm not sure how easy a transit would be to align the coupling, stuffing box and strut but if you have the knowledge use it. For my boat I didn't have to remove the rudder to get the shaft out. With a "fin" strut it was bit of an exercise to get the strut line up.


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## tristan35 (Oct 30, 2016)

John, we have hull #33 and live up in Boston so it seems like we might have plenty to discuss!
I'll PM you my contact info.
Tristan


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## TAPH2O (Jan 6, 2018)

Ok I’ll bite my daughter is having a strut welded up of stainless steel $500 as opposed to $1400 for new bronze casting on an Ericson 36c Why not stainless Steel?


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