Can I build my own stainless rudder?

Discussion in 'Inboards' started by mongo75, Aug 20, 2008.

  1. mongo75
    Joined: Aug 2007
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    Location: Orange County California

    mongo75 Senior Member

    The 25' Luhrs I am currently restoring came with a bronze rudder that has some deep pitting on the shaft. My question is, since I tried to braze the pitting and didn't have too much luck there, could either (A) fill the pitting with JB weld and sand to shape, or should I just make a new one out of stainless? If I were to make on out of stainless, is it ok to make it bigger to get better response from it (it's a single screw)

  2. BHOFM
    Joined: Jun 2008
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    BHOFM Senior Member

    There is a process called silver brazing, I can't find any info
    about it now, but I did some on some small parts a few
    years ago!

    Maybe someone here is familiar with the process and
    can set you in the right direction! I am sure this will
    repair the problem with your rudder!

    You need a special flux and rod and lots of heat!
  3. Eric Sponberg
    Joined: Dec 2001
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    Location: On board Corroboree

    Eric Sponberg Senior Member

    Consult a naval architect to make a new design rudder for you. There is a lot to rudder design, and if you don't know what you are doing, you can easily overload the steering system, shaft, and bearings. You could also add too much control to the boat and that can almost be worse than not enough control.

    Also, if you want to make a new rudder in stainless steel, you have to use an "L" designation stainless, such as 304L or 316L. These are "Low Carbon" stainless steels. If you do not use these, then in salt water with lots of oxygen near the surface where the rudder is, the welds will easily pit and corrode due to carbide precipitation. That is, the carbide in the steel precipitates out of the metal in the vicinity of the weld, leaving an unprotected region in the heat-affected zone of the weld. In oxygen rich seawater, the heat affected zone corrodes very fast due to the carbide precipitation in that area. You'll lose your rudder pretty quickly.

    Again, consult a naval architect for a new rudder design.

  4. lazeyjack

    lazeyjack Guest

    if you send me the plan of your rudder I will design a foil in ss, for free
    To fix your old one
    get a power wire brush and make those pits shine
    to bronze weld it, you have two choices, one you can use stick metal arc, using monel rods , WHICH ONLY WORLK ON REVERSE POLARITY, BUT WILL WORK
    Or you can braze using bronze rod, the drill here is you must heat the parent metal, in this case your rudder:) til it glows, lay it on some bricks
    Using a big gas tip and a carbonising flame, not an oxidising flame, if you dont know what these are maybe you should not be attempting this, heat the whole rudder near the spots you want to fill, if you were in a dark place the rudder will have to glow, then using plenty of flux on the rod, it should flow on, silver brazing is much different usews low temp filler same as plumbers use
    sounds like this is a flat plate thing, a new foil type would benefit
  5. mongo75
    Joined: Aug 2007
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    Location: Orange County California

    mongo75 Senior Member

    Thnaks everyone for the responses! I did try to fill the pits with brazing rod I got from Lowes hardware, with the flux on them. It took in a few spots, but others it just melted off, I'm guessing I didn't heat it enough. Since it DID work in a few spots, should I just try it again, or would I just be better off building a new one, and maybe just add an extra inch to the end of it? Basically it's a 1 1/8th" rod with none of the blade in front of the rod.
  6. alan white
    Joined: Mar 2007
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    Location: maine

    alan white Senior Member

    I'd guess the shaft could be spray welded and re-turned to build it back to original. Machine shops do it all the time to steel shafts. Maybe bronze too.

  7. mongo75
    Joined: Aug 2007
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    Location: Orange County California

    mongo75 Senior Member

    What's spray welded?

  8. lazeyjack

    lazeyjack Guest

    you have a big torch with a pot of metal powder on it, you can overlay any metal with most any metal, I used to build bark destripping knives up with tungsten, that was in the 70,s, its not called spray welding, but hey I forgot what the correct term is, i really am getting ancienne, I remember its just called metal spraying, you need some special gear and an oxy acetylene set, for a one off no good, but your parent needs to be red hot too, , sure you could have your shaft built up this way then turned down,allow two hrs to do the coating and an hour in lathe, thats about 210 dollars, plus the cost of the bronze or monel powder
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