Good Stainless Prop Shaft Shaft Manufacturer in US

[ItDepends]

Originally Posted by boatpoker

You do realize that anything with carbon in it and contacting a steel shaft flange or manganese bronze or aluminum propeller would destroy them in short order through galvanic corrosion, right ?

Boatpoker: You have looked at a LOT of boats. Have you EVER seen a "nylon" prop shaft log??? Oh, no wait, it's not nylon, its Dupont "not nylon".

[skipperpete]

Originally Posted by boatpoker

You do realize that anything with carbon in it and contacting a steel shaft flange or manganese bronze or aluminum propeller would destroy them in short order through galvanic corrosion, right ?

PSS beg to differ[ATTACH]266493

[boatpoker]

Originally Posted by skipperpete

PSS beg to differ[ATTACH]266493

I named manganese bronze (ropellers), steel (shaft flanges and aluminum (propellers), common marine metals in contact with shafts. Please show where I mentioned stainless steel.

[wingssail]

This happened to our bronze strut as well. The bronze around the cutlass bearing was becoming pink and soft but the blade coming down from the hull was solid.

We had the cutlass bearing portion cut off and a new one made of stainless steel with two tabs coming up which slipped over the remaining bronze blade. Three strong bolts connected the new piece to the existing bronze blade.

Not very streamlined but strong.

We also installed two flat discs of zinc to the sides of the bronze strut blade

This was done in NZ in 1998. It is still in place and working well (with the same cutlass bearing) today in 2022, however we change the zincs when we haul out.

Photo: After pressure wash, Columbia, 2013. (There are also shaft zincs, not visible)

[silverp40]

Thank you and greetings Wingssail (used to follow your blog many years ago). Your solution seems great.



Ours has a similar "softer" issue also but blade been showing signs of pitting/pinkish/soft sounding metal (when tapped with hammer) for years now. Its one project Ive been dreading and postponing for a long time.



The strut has 2 thru bolts that connect some of the bonding (green ) cables. One of them has a small leak and to properly repair it I'd have to pull the strut off , meaning grind bunch of glass off. In the meantime, I'm sure the hull layup is getting good bit of soaking around the strut area...not desirable . Planning on removing it, and letting the area dry a few months while we're back in the States getting another one made.


Composite, with epoxy resin and carbon fiber layup seems like a very attractive solution. No more disk zincs on either side nor worries about interaction with our stainless prop, shaft and rudder gudgeon and bearing.

[steamgoat]

If you need a strut cast, Algonac Marine Cast have patterns for many boats and will cast you a new one.

[DougR]

Buck Algonquin has various struts available as well as “universal” struts that you bond into the hull.

Mystic River Foundry can do custom casting. 860-536-7634

I had good experience with Morel Industries in the Seattle area custom casting an autopilot tiller for me from Mag Bronze. I built and sent them a pattern and they duplicated it. They also can cast and machine a new strut using your existing strut as a pattern.
Wide variety of alloys available that they can assist you with. A variety of marine struts, rudders, etc for various boat builders.
Contact info: 360-691-9722 morelindustries.com

[silverp40]

Many thanks for the leads. I'll follow up with them.

Cheers

[Bowdrie]

Originally Posted by silverp40

The strut has 2 thru bolts that connect some of the bonding (green ) cables.

Ah yes, it took 20 posts before we are told what perhaps is the "key" to the problem.
The bonded bronze sleeve that holds the cutlass and it is only fractions of an inch from a stainless shaft that is undoubtedly electrically connected to the engine, (which undoubtedly is also serving as the "Master Ground" for the entire boat.
Where all the stray currants from whatever source can mix/mingle and go down the shaft as well as the bonding scheme.
Bronze, (assuming quality metallurgy, not some stuff that's really Brass,) can last almost forever if you just leave it alone.
Don't use it as a device to push electrons into the water and don't use it as a device to collect electrons from another source.

[silverp40]

Originally Posted by Bowdrie

Ah yes, it took 20 posts before we are told what perhaps is the "key" to the problem.
The bonded bronze sleeve that holds the cutlass and it is only fractions of an inch from a stainless shaft that is undoubtedly electrically connected to the engine, (which undoubtedly is also serving as the "Master Ground" for the entire boat.
Where all the stray currants from whatever source can mix/mingle and go down the shaft as well as the bonding scheme.
Bronze, (assuming quality metallurgy, not some stuff that's really Brass,) can last almost forever if you just leave it alone.
Don't use it as a device to push electrons into the water and don't use it as a device to collect electrons from another source.

Bowdrie, this is a cast silicon bronze strut that's been in use for 45 years, not brass. It's been double zinced this whole time and not looking/sounding much different than when we bought the boat 20 years ago. Even being the only bronze item amongst all stainless parts surrounding it, shaft, prop, gudgeon.



Main reason I'm replacing it is cause I have to remove it (difficult) to properly repair the small leak.


Higher bronzes do last almost forever except when used in certain applications like a shaft strut where they get millions of vibration cycles... which create the metal fatigue factor.



And bronze has a much lower tolerance to fatigue than other metals like stainless steel.


Its isolated from the main ground by the cutless bearing but sure, not perfectly... there are always some (some boats have a lot) of stray currents circulating around the running gear.



Bonding does not push electrons through unless tied to main ground.


Thanks for the great points you made though.


Cheers

[Mickeyrouse]

Originally Posted by Searles

Use the old one,as a pattern get a new one cast in alu bronze the easiest way to go .⛵️⚓️

Pattern making for foundry work is a little more complicated than that.
Accurate patterns are made in two matching pieces, the cope half and the drag half. Pattern making is a detailed precision skill. And the work isn’t cheap. Patterns to be used for bronze casting may not have the same dimensions as those intended for casting in other metals due to different coefficients of expansion of the molten metals.
Patterns are almost worth their weight in gold, even though they have historically been constructed in wood, usually mahogany. When the patterns for the marine pieces manufactured and sold by Wilcox-Crittenden burned in a warehouse fire about 20 years ago, some dating back to the Age of Sail, the company went out of business shortly thereafter. And that’s why, among other reasons, you can’t find parts for Wilcox-Crittenden toilets anymore.

[Bowdrie]

Originally Posted by silverp40

Hello all, our 44 year old bronze propeller strut is showing significant signs of dezincing. Plus one of the 2 electrical grounding screws that penetrate the hull have developed a small leak.

Originally Posted by silverp40

Bowdrie, this is a cast silicon bronze strut that's been in use for 45 years, not brass. It's been double zinced this whole time and not looking/sounding much different than when we bought the boat 20 years ago.
Main reason I'm replacing it is cause I have to remove it (difficult) to properly repair the small leak.
Its isolated from the main ground by the cutless bearing but sure, not perfectly... there are always some (some boats have a lot) of stray currents circulating around the running gear.
Bonding does not push electrons through unless tied to main ground.
Thanks for the great points you made though.

Ok, in post #1 you tell us that the strut "shows significant signs of dezincing"
Then, in post #25 you tell us that it's
"not looking/sounding much different than when we bought the boat 20 years ago."

What am I to make of that, concerning my response?
What does "not perfectly" mean about bonding, it either is or it isn't.
Either the bonding wire is connected to ships ground, or it isn't, there is no middle path, perhaps except for bilge water.
I seriously doubt the strut was cast in Silicon Bronze, much more likely to be of Manganese Bronze.
Adding zincs to Bronze is counterproductive to its lifespan, especially when connected to a bonding scheme.
Have you considered that the leakage thru the bolt may in some ways have been caused by deterioration of the bolt caused by stray currant(s) due to your unnecessary Zincs/bonding?
As an aside, the chart(s) that show the ranking of the nobility of various metals is NOT etched in stone.
As soon as electricity is entered into the mix the rankings get all changed depending upon the electrical flow/direction of flow, and the electrolyte the metal is submerged in.
Even AC is changed, the two halves' of the sine wave becoming un-equal, so that a plating/un-plating phenomenon occurs leading to effects similar to DC.
Who knows what evil lurks in the hearts of electrons that are allowed passage into submerged metal.

[silverp40]

My Quote:


Its isolated from the main ground by the cutless bearing but sure, not perfectly... there are always some (some boats have a lot) of stray currents circulating around the running gear.



Should have added "stray currents in the water



Otherwise the bonding is isolated from the main ground.