Rudder and hull fiberglass

Rudder plug


I printed out NACA0020 foil that Rick suggests using for the rudder -
man it looks tiny, but I guess a stern hung rudder, like the typical
ocean rowing boat is about 1/3 rd the effectiveness for a given area
of a non-aerating position under the hull. The rudder is 12" long x 5"
wide by an inch thick.

I used my micro scroll saw to cut the tight curve at the end of each airfoil because the cut needed to be squarer than my x-acto knife would cut.

I cut twelve NACA0020 foil shapes out of 1" thick Styrofoam and hot
glued the stack together using a guide that to ensure that the stack
was perfectly straight and square.

I sanding the stack down with a sanding block and sculpted out the
trailing edge of the rudder. I was pleased with the outcome. Then I
spray glued about 6 layers of fiberglass fabric to it, and I'll wait
until the hull is out of the vacuum bag before I epoxy and bag the

Then I will dissolve the foam with some gasoline, and insert my 1" OD
stainless tube. The rudder tube will have smaller 'branches' welded to
the end where it is inserted into the hollow fiberglass rudder fin to
grab onto the epoxy/micro mix that will I fill it up with.

Deck Fiberglass

Ben and Helen were my helpers today. We got messy with epoxy and
wetted out the entire 2 layers of fiberglass roving in the Hyak deck.
We finished in about 3 hours which must be some kind of record. I'll
pull it out of the vacuum bag tomorrow and start thinking about the
drive leg well. I'm thinking of building it with Marine plywood, then
glassing it. It needs to be super strong.


7 Responses to “Rudder and hull fiberglass”

  1. # Anonymous Anonymous

    Ben you're starting to look buff in the last picture :-)  

  2. # Anonymous Greg Nuspel

    Greg if you have to cut more foil shapes there is a computer controlled 4 axis foam cutter in town that I built. I'm sure I could get you some cut on it.  

  3. # Blogger Adventures of Greg

    Ben - stop posting comments anonymously!  

  4. # Anonymous Anonymous

    This pic shows a motorized high-speed submersible, note the snorkel up top.

    Dave (DDeden)  

  5. # Anonymous Simon Martin

    Hello Greg,

    Just a question regarding the rudder shape: I see on the CAD drawing that the rudder shaft is positionned near the straight side of the rudder blade, then on the pictures I see you shaped the rudder the other way, the edge of attack being on the rounded side of the profile outline: why has this been changed? So that debris have better chance to flow free of the rudder blade by themselves?

    Thanks for the inspiration by the way, I am making your endeavor known to as much people as I can around me, and everybody agrees that you are a bright example of "if one wants, one can!" (I don't know if it's the right way to say that in english!)

    Allright, sorry for the long story!

  6. # Blogger Adventures of Greg

    ah - someone is paying attention! I certainly wasn't! I goofed up and rounded the wrong part of the rudder. As it turns out, it doesn't really matter that much which side you round - if any. One advantage to rounding the leading edge, as you said, is to shed weeds and other obstacles.


  7. # Anonymous Ron Hongsermeier

    Hi Greg,
    you're being a busy boy again.

    As to the rudder shape, it seems a bit thick to me, not on basis of any empirical evidence-- just feeling for boat that size.

    Second: very small inaccuracies in your fairing of the curve in the rudder may mitigate what you save in reduced surface area by unfairness; i.e., you probably won't notice much difference in leaving the rudder with a "square" top and bottom over against the two different curved faired possibilities. Apart from the weeds and obstacles observation at least.  

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