35-3 New Strut [Master Thread]

[bigd14]

It seems the bolts were only used as an anchor for the mish-mash to be packed around.

I agree. When I tore out my strut it was evident that someone had purposefully wrapped strands of fiberglass fabric around the six bolts to tie it to the rest of the filler material. I attempted to do the same with the new strut. So far so good 4 years on…

 

[Nick J]

This project is finally wrapping up. They glassed over the filled in cavity on the inside and glassed and fared the outside. They're going to spend next week aligning the engine and finishing up the faring and bottom paint. Although I would still like to have done this myself, I wasn't able to spend any time on the boat this week, so it was nice still getting work done while I was stuck at work.

 

[Nick J]

More pics of the work the yard did this week. They said there's probably one more round of faring and sanding before the bottom paint goes on. This week will be focused on the engine alignment and dripless shaft seal install.

 

[Kenneth K]

So, after all the work replacing the strut is complete, will the yard recommend attaching zinc anodes???

 

[Pete the Cat]

So the engine is not coupled and set right now while the installation was going on? I thought that was the process.

 

[Nick J]

I didn't get a definitive answer on that. At first the foundry said it would have benefited form a zinc. When I picked it up, we discussed it again and they recommended leaving it off for the first haul out and assessing it next time. He said the original was almost 40 years old so there's no rush and it would be good to get an idea of how it's doing in it's current slip. If the yard wants to put one on, I'm not going to complain. If not, I'll go with the foundry's recommendation.

 

[Nick J]

So the engine is not coupled and set right now while the installation was going on? I thought that was the process.

Me too. It was coupled then they took it apart. The yard said they were having a hard time aligning the engine after the strut was set and some of the new holes weren't working. I don't understand how that could happen with the template being accurate. The good news is the strut is aligned with the shaft log, so the difficult work is done. Hopefully we'll find out more today.

I'm trying not to focus too much on this because it's pretty stressful. My mind starts going down the path of needing to pull the engine again to reglass the new holes and start over and I really don't want to think about that right now. The yard said they're optomistic it will go well and they are just off becasue the weight of the engine caused it to slide down the stringers. Hopefully that's the case.

 

[Prairie Schooner]

I didn't get a definitive answer on that. At first the foundry said it would have benefited form a zinc. When I picked it up, we discussed it again and they recommended leaving it off for the first haul out and assessing it next time. He said the original was almost 40 years old so there's no rush and it would be good to get an idea of how it's doing in it's current slip. If the yard wants to put one on, I'm not going to complain. If not, I'll go with the foundry's recommendation.

Nick, I just posted in our strut thread my decision on a strut zinc. Short answer, yes.

 

[Parrothead]

Nick, I just posted in our strut thread my decision on a strut zinc. Short answer, yes.

Yep, there's no downside.

 

[Pete the Cat]

Me too. It was coupled then they took it apart. The yard said they were having a hard time aligning the engine after the strut was set and some of the new holes weren't working. I don't understand how that could happen with the template being accurate. The good news is the strut is aligned with the shaft log, so the difficult work is done. Hopefully we'll find out more today.

I'm trying not to focus too much on this because it's pretty stressful. My mind starts going down the path of needing to pull the engine again to reglass the new holes and start over and I really don't want to think about that right now. The yard said they're optomistic it will go well and they are just off becasue the weight of the engine caused it to slide down the stringers. Hopefully that's the case.

I would have expected they would not be drilling the holes until the engine was coupled, but whatever. It should not be too hard to align the engine with shims if everything is near perfect. It is important to get it centered in the down tube as you note. Fooling with shims is what competent yards do in the alignment process when they are servicing boat drive systems. It was just that they had a unique opportunity to get it perfect and you seemed have done all the work for them. It will be fine. You are taking way more care than most yards I have worked in, and the pictures show excellent work throughout. If you want to supervise the result, just ensure that most of the alignment nuts are more or less centered on the studs---not all the way at the top or bottom (they should use shims to prevent this).

 

[Pete the Cat]

BTW-- I have a large zinc disc zinc on my strut that seems to get the most annual deterioration--more than my propeller (Autostream feathering SS) and shaft zincs. BUT my Tartan's strut is bonded to the engine, keel bolts, and mast (I think Tartan did this as a lightning protection) so I would not assume that your experience would follow. Helpful, eh??? My boatyard friends tell me that you can overdo zincs on a wooden boat (fasteners), but not on a fiberglass boat--not sure of the rationale. I don't have a strut zinc on my new-to-me 1989 Ericson, so I am following this with some interest. Seems like the convention is to not put a zinc on the strut but that could be cheap factory and lazy yard stuff--there is a lot of both in my boat experience. I just think there would be no harm in it and it is cheap insurance. I think I will put one on the Ericson at the next haulout.

 

[Puget sailor]

Really interesting thread. Especially since I was squinting hard to avoid focusing on the evidence of corrosion on my 32-3 strut at my first haul out last spring. Mine had been retrofitted with as small rudder zinc on one side. I decided to sandwich it with much larger ones on both sides since I felt the need for more protection.

I do wonder about the viability of:
A: making these parts from modern materials like carbon fiber
B: making these parts with modern methods like 3d printing or cnc machining from billet blocks
C: Reinforcing corroded parts with high tech composite materials, or low tech welding then and machining in situ.

Finally, noting the challenge and cost of replicating the original exactly, might it not make sense to create some sort of survey on this site to see who might be interested in a go-fund-me type contribution to getting new molds made for struts for any Ericson boats where there is not a readily available stock part available? Knowing, for example, that mine is sketchy, I'd be interested in kicking in a benjamin to anyone who was getting PT foundry to be able to cast an exact copy of an E32-3 strut, and there might even be some economy of scale options if several were ordered at once from the foundry? Even if I was not planning to replace mine immediately, if there was an opportunity to buy a fresh casting for 500 or 600 bucks to add to the bilge ballast, I'd be quite tempted.

 

[Jerry VB]

A: making these parts from modern materials like carbon fiber

Carbon fiber is very galvanically active when contacting aluminum or plain steel. It is believed that it will enhance pitting corrosion in stainless. Titanium is OK, however.

The Boeing 787, which uses carbon composite construction heavily, uses titanium extensively to avoid galvanic corrosion.

Ref: Galvanic Corrosion of Metals Connected to Carbon Fiber Reinforced Polymers

 

[Nick J]

Finally, noting the challenge and cost of replicating the original exactly, might it not make sense to create some sort of survey on this site to see who might be interested in a go-fund-me type contribution to getting new molds made for struts for any Ericson boats where there is not a readily available stock part available? Knowing, for example, that mine is sketchy, I'd be interested in kicking in a benjamin to anyone who was getting PT foundry to be able to cast an exact copy of an E32-3 strut, and there might even be some economy of scale options if several were ordered at once from the foundry? Even if I was not planning to replace mine immediately, if there was an opportunity to buy a fresh casting for 500 or 600 bucks to add to the bilge ballast, I'd be quite tempted.

all of the foundries I talked to said creating an exact copy isn't worth it because calculating the shrinkage is more of an art than science and you'll always end up with a slightly different part. Especially on our boats where the strut is installed from the top, you have to remove so much material anyway, there's no real advantage to having an exact replica. That being said, the closer the replacement part is to the original, the less amount of filler needed to bed the new strut. Marine Hardware in Redmond, WA claims to have the original pattern, but they have a 10-12 week lead time.

I did ask the yard for the old strut so if I ever find some extra time, I can fiddle around with making a composite copy. I don't know if I'll ever get around to it and I will hopefully never need another one, but I thought it would be interesting.

 

[Nick J]

Carbon fiber is very galvanically active when contacting aluminum or plain steel. It is believed that it will enhance pitting corrosion in stainless. Titanium is OK, however.

The Boeing 787, which uses carbon composite construction heavily, uses titanium extensively to avoid galvanic corrosion.

Ref: Galvanic Corrosion of Metals Connected to Carbon Fiber Reinforced Polymers

I may be wrong, but I think that's only an issue if the metal is in direct contact with the carbon. Since Carbon is extremely noble, the issue would be with the other metals connected. A strut is isolated form all other metals unless you deliberately connected it. If this was a problem, I would think there would be a bigger issue with all of the high tech boats being produced. I'll probably never have carbon above or below the waterline on my boat, but that's more of a financial decision than a worry of galvanic corrosion.

To keep it in perspective, the struts we all have on all our boats are actually brass and we've all heard about the downsides of brass, but here we are with 30-40 year old struts just now showing their age.

 

[Loren Beach]

To keep it in perspective, the struts we all have on all our boats are actually brass and we've all heard about the downsides of brass, but here we are with 30-40 year old struts just now showing their age.

I believe that they are specifically not brass, but rather bronze. Or so I have always been told.

 

[Nick J]

That's what I thought, but.... manganese bronze has zinc, so it's actually brass. There's some discussion above in the thread. As evident by the longevity of most props and struts, it's more than suited to be used. Calling it brass is more if a fun did bit of trivia than explaining it's corrosion resistance.

 

[Christian Williams]

Carbon fiber would be my last choice for a strut, or anything else not requiring super lightness. And even then it has become my last choice.

 

[Kenneth K]

I think the strut-zinc issue has developed its share of misunderstandings over the years too.

I stripped all the barrier coat from my strut and added zincs due to the advice from my yard, which was emphatic that copper-based anti-fouling paint can corrode the strut.

It was years later, when further researching the topic, that I read that the specific advice I received originated from a manufacturer of aluminum outdrives for powerboats. Makes sense that copper paint would cause galvanic issues with aluminum outdrives. Not so much on an isolated sailboat strut.

That's one of the problem with boatyard folklore, adages, and yarns.

 

[Nick J]

Here's some pics of the (almost) finished job. The yard's installing the prop tomorrow and I'm finishing up a few things with the transmission control cables.