corrosion of rudder stock

[Squeaky]

Good morning:

A friend has removed his rudder to change the bearing and discovered that the bronze stock is corroded for several inches above where it disappears into the rudder. The yacht is an Allied Sea Wind built in the mid-seventies.

It appeared that the diameter has been reduced by 3 or 4 mm over several inches.

The question is what should be done. It has been suggested that an inch of two of the rudder material should be removed to see if the corrosion extends down into the rudder and if not that the affected area be ground back to bare metal and then built up with welding/brazing (what ever the procedure is called) and then "faired" as well as possible because it will not be possible to put the rudder on a lathe.

Any suggestions/comments welcome.

Squeaky

 

[vyv_cox]

It's a little difficult to tell from your photos but it appears that there may have been a sleeve over an internal bar and the sleeve has corroded? It may be possible to replace the sleeve. The problem with a brazed repair is that the composition of the original and repaired metals will inevitably be different. Braze is normally a brass alloy, although there are many varieties. Even by selecting the best for corrosion resistance, galvanic corrosion is inevitable and the repair may soon fail.

 

[Neil_Y]

That's not an area I'd be happy with repairing (if it was my boat) As Vyv sais brazing is not ideal and even if it were stainless you'd want to sleeve it down into the rudder blade for a repair that would be as strong as an original un-damaged shaft.

If it's going to fail this is where the most stress is and failed rudders can be quite a problem.

Somebody from here may help with their experiences
http://www.alliedseawindii.org/

 

[Squeaky]

Good afternoon:

Things have moved on and it has been suggested that a new rudder and stock be made using stainless steel for both the rudder (10mm s/s) and stock with a flange permitting the rudder to be disconnected without the need of removing the stock meaning rudder could be removed without the need to suspend the boat in slings or digging a hole in the ground under the rudder.

The owner has had a firm quote of 1,000 euros for the above s/s rudder and stock.

In addition he has had a number of ball park quotes for opening the rudder and replacing the stock before closing the rudder and retaping the seam. I believe these quotes include a s/s stock. The owner is in the process of firming up these quotes before making a decision during the week-end on how to proceed.

The s/s rudder would be of the same shape in 10 mm s/s as the original and the stock would also be s/s similiar to the original bronze stock.

Attached are a couple of additional images showing the shape of the rudder and a poor image of the aft part of the keel.

Comments welcome.

Squeaky

P.S Forgot to mention that there was no sleeve on the original - the apparent sleeve is just the way the stock corroded allowing layers to be peeled off.

 

[garvellachs]

Heavy?

A 10mm stainless rudder sounds very heavy to me? If it's a lot heavier than the old one you may need to look at the strength of the bearings that support it too.

 

[minkysailing]

Squeaky,

I have just in the last 2 weeks surveyed and overseen the replacement of a badly corroded aluminium stock on a Najad rudder. Have a look at my news article on my website. Happy to assist or answer any questions if you wish to contact me.

 

[Oldhairy]

a new rudder and stock be made using stainless steel for both the rudder (10mm s/s) and stock with a flange
The owner has had a firm quote of 1,000 euros for the above s/s rudder and stock.
In addition he has had a number of ball park quotes for opening the rudder and replacing the stock before closing the rudder and retaping the seam.
Comments welcome.

Squeaky

A stainless rudder would be OK if you could guarantee to never ever go aground and dry out. If you do go aground sods law dictates that the trailing end of the rudder will dig in nicely and the boat will be supported by the, now possibly bent, stock.
You might also induce lee helm.
Personally I would ,without hesitation, replace the stock. The flange sounds like a good idea.

 

[Blueboatman]

May I suggest that the OP weighs the existing rudder before commissioning a all metal replacement?
It may well be that the existing rudder has neutral buoyancy so that it is not pulling 'down' on the helm when the boat us heeled.
This, and the possibility that a plain metal rudder may not be as 'faired' at its leading edge, being 10mm only, would encourage me to open up the existing rudder and replace the stock with a new, two part flanged one.