Rudder and Boat Stand


I covered my Styrofoam rudder plug with a few layers of light weight fiberglass cloth and two layers of Kevlar, whetted it out with epoxy resin, then vacuum bagged it. When I removed the rudder from the bag, a couple of outside layers of fiberglass had bunched up and made a very small crease along the leading edge of the NACA0020 airfoil. After grinding this ridge off, I noticed that the composite skin was especially thin and weak along the leading edge which is not good because that is the edge that will need to withstand debris, weeds, rocks and the occasional shore.

To reinforce the leading edge, I added another layer of Kevlar and a layer of carbon fiber. This time instead of vacuum bagging it, I wrapped it with shrink wrap which worked WAY better. It resulted in a very tight, hard and smooth surface. To further toughen that leading edge, I could insert another layer of carbon to the inside of the rudder after I dissolve out the Styrofoam.

The next step is to cut the top of the rudder off at the correct angle so that it meets up flush against the bottom of the hull. Then I dissolve the Styrofoam plug, weld some branches onto the end my 1" OD stainless rudder tube, place the tube into the hollow rudder, and fill the rudder up with an epoxy/micro/carbon strands mix.

Stand for Within

I realized that I needed a better stand for the kayak hull, so I made three wood stands to support it. It's just high enough off the ground to allow the prop to spin, so I will be able to climb in, sit in the seat and do some stationary dry-land training and testing of the drive. After i get the drive leg and seat in, I would like to re-visit my original power test:

With my SRM power meter, I had measured the following efficiencies for power transmission from the cranks to the spinning prop:

STRAIGHT CHAIN = 100% (set to 100% as baseline)



I would expect to maintain 94.1%, but I will probably lose a % due to the chain clinking along the stainless steel tube guides. Then again, the right angle gear box has not been run in yet, so I may gain some efficiency.

When we added the two layers of fiberglass roving to the Nimbus kayak hull, we hot glued a 1" wide x .5" thick strip of Styrofoam to the perimeter of the kayak just under the thin lip. Then we tapered (by sanding) the lower edge of the foam so that it met flush with the hull. After this was glassed, it provides a solid edge to matte with the 1/2" thick edge on the deck.


2 Responses to “Rudder and Boat Stand”

  1. # Blogger scott

    I'm imagine you are aware that carbon fiber is one of the most galvanically active substances and will be expecially so in salt water. I was wondering whether you might be better off to use a carbon fiber tube instead of stainless...  

  2. # Blogger Adventures of Greg

    If carbon is galvanically active in salt water, shouldn't ibe using stainless?


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