lm27 rudder clamp corrosion

[oceandancer]

Hi All,

Here is a cautionary note regarding the upper LM27 rudder clamp, the one where the tapered pin fits through.

As have many of us,  I have not paid really close attention to this, it's normally covered in antifoul and it just gets painted again every time the antifoul is topped up. I only noticed some severe corrosion damage on removing the rudder in the process of changing the cutlass bearing.

I have included a picture which I hope gives an idea of the damage. The corrosion pit has not penetrated right through the central collar which is about 6mm thick. I hope it can be repaired and will be taking it to the welder on tuesday. If not it would be a fairly difficult item to duplicate and absolute precision would be required in order to align the holes with the rudder shaft hole AND to provide the same morse taper across the collar. I estimate that it would take a fabricator most of a day to do it with a corresponding price tag. The clamps top and bottom do not appear to be made of stainless steel.

I shall be adding a small anode along the top of the rudder when it gets put back.

So,  when you next antifoul make a point of scraping off the old paint to assess the condition of your clamps.

Mick

[wilhelm]

Hello Mick, bit of a worry finding the corrosion hope the welder can build up on the lost metal. Question, do I take it that the two clamps hold the paddle part of rudder to the stock and they are manufactured in Mild steel, pinned to Stl Stl shaft ! if this is the case other members should take heed of your finding. Having repaired a rudder and about to help my son repair rudder on a Westerly. The std. make up for rudder is of two halves moulded round a Stl. Stl. frame then the two halves glassed together. 

I do have an anode mounted on top of my rudder connected to clamp but intend to check situation. Survey report when we purchased our 27 about three years ago commenting rudder having water ingress, and to  drill a hole in bottom of rudder to drain repeating annually allowing rudder to dry out over winter.

Good luck and thanks for advice.

Wilhelm









   

[oceandancer]

Hi Wilhelm,

The welder did a good job of restoring the rudder clamp. it looked almost like new. He said it was stainless steel although it did not look like it and was slightly magnetic,however, when I tried to reassemble it I found that the central collar which is very thick seemed to have been distorted a little bit in the heat and it would not fit onto the rudder shaft.It took an hour with a round file carefully taking off the high spots revealed but turning it round on the shaft. It now fits very well and I have anodes top and bottom fitted to the edge of the rudder and electrically bonded to the clamps.
I am now sailing in the sunshine at last!

Regards

Mick

[Sula]

Hi Mick,

Thanks for the useful information and warning.

I too have until now 'left well alone' and and not previously investigated my clamp and tapered pin, important though they are. (There always seem to be more urgent things to do.)

Stainless steels are often slightly magnetic - the amount of responsiveness to magnetism (from quite a lot to negligible, apparently) depends on the particular type.

John

[wilhelm]

Well done Mick, and once again thanks for info. We often admire your boat in the marina a real cracker. 

Regarding your comment now sailing we are envious, being in total lock down due to this plague !.

Wilhelm