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Drilling bare rudders  Bottom

  • The head of one of my Nacra 450's original rudders has split and expanded to the point that it is beyond my meager fiberglass skills to repair. Luckily, Murray's was able to find a similar blade in their warehouse. The new board is bare with no holes drilled or bushings installed. Any advice on what bushings to use and how to install them?

    Looking through the usual sites only shows plastic bushings while what is currently installed appear to be a stainless/aluminum tube captured inside the blade.
  • If you can measure the inside and outside diameters of your existing bushing or spacer, it is very easy to find aluminum spacers made to that specification. I don't know what you need, but it would be a cinch to find "Aluminum Spacer Bushing, 1/2″ OD, 3/8″ ID" even on a site like Amazon, as well as many automotive and parts machining sites. Spacers will come in many lengths, but it should be easy to cut to size. The main use of the spacer is to prevent wear and elongation of the hole, and older boats were produced with just a hole bored in the rudder.

    NACRA 5.7 (1984 Sail 181)
  • Use a SS spacer if possible, the bolt will be SS and so should the spacer. Dissimilar metals do not act well together.
  • Delrin seems to work pretty good as a spacer on other boats, but you can't glue it in very well (slippery), if you're trying to do that...

    Chuck C.
    H21SE 408
  • Thanks for the advice all. I found some stainless steel spacers that should work. Any thoughts on how to secure them...I was thinking epoxy?
  • If the rudder head is foam core, then you could probably drill the holes and then carve out some of the foam and then epoxy the bushing in place. That will give the epoxy some area to adhere to. If you try to epoxy the bushing into a hole that fights tight to the bushing, then all of the epoxy will be scraped off when you push in the bushing.

    If the rudder head is solid fiberglass, then consider drilling the holes using a slightly under-sized reamer (a couple thousandths less then the bushing OD) and the tap the bushing in for a press-fit.

    Another option, if the rudder head is foam cored, would be to drill the holes in the rudder oversized. Then fill the hole with thickned epoxy. Then re-drill to the final diameter after the epoxy cures. I have done this on Hobie EPO rudders. The epoxy seals the foam and also acts as a bushing. The hole can then also be easily re-filled and re-drilled if the position needs to be adjusted slightly.

  • What kind of foam does Hobie use on EPO rudders?

    Chuck C.
    H21SE 408
  • Simple!
    Use the bushing from your old rudder.
    Drill a whole for it, use the bushing as template. If my mind serves me well I used 10mm, but you can probably go down to 9,7mm.
    Nacra do not use anything to close the foam in the rudder, if you want to add something, use epoxy.

    Edited by revintage on Nov 16, 2022 - 03:45 PM.


    Frankentri 5.8/5.5/Inter20
    Aerow trimaran foiler


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