reparing a crashed rudder..

Zed Nivel

Zed Nivel

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Hi all - as I had damage on rudder and keel in Lefkada Chanal (already I have alerted abt the dangers there) I now must repair my boat a 40 foot Bavaria.
The shaft/axle is SS and on that is pressed a material "bearings" but of course with the opposite function.
These existing items looks like nylon, POM (Polyoximetylen) or Acetal.
Now - of course i want some kind of guider as "medium" bonding well to the GRP?
 
Hi Zed,

I was sorry to read about your bad luck damaging the rudder. I would try Sikkaflex for fixing the Nylon, POM or Acetal bushes into the GRP.
 
[ QUOTE ]
I would try Sikkaflex for fixing the Nylon, POM or Acetal bushes into the GRP.

[/ QUOTE ] Which particular Sikaflex product are you suggesting. There are many. Sikaflex 292?


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Hello John
thanks for tip! But but..
do you really suggest that i use Sikaflex in the fitting between shaft and GRP ( construction inside the rudderblade)
 
Other posts are talking about nylon bearings - Now I will be the first to accept that the level of my knowledge here is not excessive, but from previous discussions I understand that nylon can swell if immersed in salt water, and that Delrin is a better material.

I await the pronouncement of somebody who does know!
 
Ohh well Delrin or Nylon - My retailer here in Göteborg recommended Nylon (which in itself has a number of different qualities). But what does he know I don´t really know. I have already ordered Nylon....And would probably go for it ..... Actually its not bearings is it -- they are prompted to be sitting well on the shaft on not at all swirl.
 
Talbot is absolutely right. I had mine replaced a couple of years ago and they were fine while the boat was drying out (bilge keel) then we went off for a week and were afloat for the majority of the time.

The nylon had swollen and it was absolute hell on the majority of the eighty miles getting home. The squeaking noise was almost deafening and it took major force to move the tiller. I had them rebushed while wet but got some Vesconite ready for next time they play up. He sent it up from South Africa. It's the biz and not a lot of people know about it. /forums/images/graemlins/smile.gif

http://www.vesconite.com/industry/marine/marine.htm

BOL
 
Hi you guys - Sorry but i am not sure you grasp what I mean: this is NOT a bearing for the shaft to swirl in. No this joint its meant to be really really stuck on to shaft and also bonded into the GRP inside the rudder. Mind All the force from the Wheel/ shaft is transported out in the rudder material via this joint and vice versa.
So i dont understand this about Nylon squeeking and swollening... in this part of the rudder its ALSO meant to be no water at all.
 
Sorry Zed,

I misunderstood your question. You should find that the end of the stainless steel shaft should have a rectangular piece of stainless steel welded to it inside the rudder (together with the shaft this looks like a letter L - like a golf club). When you take the shaft out, check it carefully to see that it is straight, if not take it to a hydraulic press and have it straightened.

You need to separate the two haves of the hollow GRP rudder (saw blade and chisel) and dig out the old foam filling. Then the shaft should be wrapped in epoxy resin/GRP, carefully aligned with the blade and and securely bonded into one half of the blade, also with epoxy-GRP. Then the two halves are bonded together around the edges with epoxy and microfibres and the joint reinforced round the outside with a layer of GRP. Through a hole bored in the top pour in 2 part polyurethane foam to fill the void and then seal the hole with GRP. Fair the blade with epoxy and microbaloons and after sanding to shape, prime and antifoul.

John

Whilst I was writing all of this, you added your post (just above) So now I think again, I have misunderstood your problem.

If the shaft is still securely attached to the blade and the shaft is not bent, perhaps it is just a thrust bearing or a thrust and radial bearing that this nylon bush provides.

An earlier post was quite right that nylon absorbs water and expands, so your new bush, if it is in nylon, needs to have a suitable clearance to avoid getting too tight in the mating part when it swells.

I don't think epoxy or polyester resins will bond with nylon, so you may still have to bed it down with sikkaflex if the adhesive is required to prevent the bush from rotating on the shaft.
 
Yes John, you are just so much better writing about my work then myself ! Well - the rudder is already dismantled and the shaft is straight but ( i would have to come back to the boat in a weeks time to see) i can only hope i will find any "ears" on the shaft that you write abt. I have only very hastily glanced thru the big cracks saw these bearing look-alike joints. Maybe i can skip these joints and come out with a much better job then the farmers in Bavaria ( hehe?)
well thanks !

you other guys Talbot and other friends: The bearings you are talking about are really fine in my boat but i have surely picked up your info thanks - can use that next time...
all the best from me - i will appear in Cleopatra Marina next week looking like an Astronaut /forums/images/graemlins/tongue.gif
 
Zed,

I'm glad I was able to reach an understanding finally. I will place this thread in my favourites and check from time to time. Do let me know how the work on the rudder is proceeding. I will be glad to help you again if I can.

John
 
[ QUOTE ]
Ohh well Delrin or Nylon - My retailer here in Göteborg recommended Nylon (which in itself has a number of different qualities). But what does he know I don´t really know. I have already ordered Nylon....And would probably go for it ..... Actually its not bearings is it -- they are prompted to be sitting well on the shaft on not at all swirl.

[/ QUOTE ]
It is my understanding that the plastic/nylon can swell up and make the effort required to move the rudder get more and more of a problem.
 
yes its understood and i have found a retailer for the material to use when its time to upgrade the REAL bearings;
Marilia in Athens sells Vesconite
//all the best
 
You are a good man taking so much time to give what it seems an accurate procedure for total renovating a crashed rudder!!!!
thanks ever so much and as said - i will document this and also publish the report on my website -- i will come back. If not remind ME pls!!!
 
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