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Dinged rudder advice please

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  • Dinged rudder advice please

    Hi all

    Its spring in New Zealand and time to sort the Stars and Stripes. Last season we hit something - we never saw what. There was prop and rudder damage, but luckily the strut and shaft stayed true. The prop got replaced and the rudder performed ok, but we had a leak.

    Im pretty sure the leak was around the box due to the sealant being compromised during the ding. I have pulled the rudder. Pics attached.

    The first bit of advice I am looking for is - how can I tell if the shaft and seal are good? I feel the slightest bit of play between the shaft and the box. The box spins smoothly on the whole length of the shaft. The box and rudder are only 5 years or so old (there was a previous more substantial impact).

    Should I just reinstall the rudder and be good to go - with a new grease nipple and grease?

    Secondly, is the small twist/impact at the bottom of the rudder a big deal? How would I go about fixing it if it needs it - a simple press or do I need heat as well?


    Attached Files

  • #2

    You mention the 84 with a newer (appears to be newer) port installed about 5 years ago. However I am not certain of the newer port but that is moot.

    Shaft and seal are good if: Shaft has an straight shot going through the port. Put a straight edge on it, shine a light behind the straight edge and the rudder shaft and see if it has little or no light. You could use a micrometer to do a Total Indicated Run-out if you suspect the straight edge method is not sufficient, but the edge method will give you a good idea.

    If the port is leaking water, it needs rebuilt in my opinion. You have it apart now.

    The OEM 84 has two seals inside for maintenance. What I see now is a newer model and from the appearance, it may have a replaceable bushing. Best way to determine that (seals vs. bushing) is to open it and look. Seals are (sort of) easy to find as well as bushings but each will have its own specifics for fitment. Not too hard to figure out. If you want to rebuild the rudder port I can offer a few U.S. sources for parts.

    Rudder is a little different opinion and others may have a better take on it than myself.

    The slight twist should be heated and straightened. A fabrication or machine shop should have heat and a press.

    The edge damage is another issue where if you clean up the area with a Rat Bastard file you could possibly take away some of the steering characteristic of the rudder. I say that relative to taking some pull out of the steering (which I do not recommend) by filing the trailing edge of the rudder to lessen the pull on the steering. That does not take much at all to alter said condition. To begin a random clean-up of the rudder's edge(s) may have an unintended consequence to the final steering; or it may not. That is a consideration and a trade-out I would consider. There is also a possibility that to leave the twist in the rudder could create an unwanted vibration. So another point to consider is that the damaged edge appears to be on the leading edge of the rudder and not the trailing edge. It could be that that will not effect the rudder at all. Water test it and see.

    I think my decision would be to straighten the rudder and test it to see if it performs to your satisfaction. The rudder is easy to drop in and out as well as the port. For now, upon reassembly, do not seal the rudder port to the hull (inside or outside) with a product that is semi-permanent (3M 4200) or permanent (3M 5200) in nature. Use 100% silicone in case you decide to remove, rebuild, and reinstall. The silicone will work fine or if you prefer the 4200 is acceptable. No 5200. I would also rebuild the port if it is leaking water. For merely a slight wiggle without a leak, you could use it until it needs further attention (not my recommendation), however you have it apart now so do the work now and be done with it. Not a hard task.

    So also to add I will say this and you may already know this; you may think that the test, or trial and error part of this is a pain because you have to remove the fuel cell. Not true. I hope you do not remove it every time you need to get in behind it. Remove the hold down brackets on the fuel cell, loosen the worm gear clamps on one end of the fuel filler hose, and rotate the fuel cell outward, about the axis of the fuel filler hose. No need to remove the hose nor remove the fuel cell. That will make it much easier to test one or more scenarios with the rudder. There is ample room to work in behind the cell like that.


    MC Master Poster
    Last edited by waterlogged882; 09-15-2020, 12:38 PM.
    93 190


    • #3

      Thanks for your detailed reply. Its is really appreciated. As you recommend, I will get the twist heated and pressed out, but leave the port and rudder - I think they are true and as you say, pulling them in the future isnt a major. I will use pure silicon.



      I will


      • #4
        Hard to tell from your photo but is the shaft of the rudder bent? The shaft should be square to the flat machined portion of the top of the rudder. If you put the rudder in a vice and level the flat on the rudder itself then put a level on the shaft it will show if the thing is bent.

        Good viewing if you like working on underwater gear on boats.