Nothing gets a debate going in the international kayaking community more then the use of rudders. On one side it is argued that the paddlers skill should be all that is needed to go in a straight line with a well designed kayak and that a rudder just adds drag. On the other side this is agreed with, but it is pointed out that even with a skilled paddler more energy is wasted on correction strokes then caused by rudder drag. My own preference is obvious.

I could have made the whole rudder system, but decided to go with a proven commercial model to save time. To keep the profile low I cut out a 1.5cm dip in the stern before attaching the deck (see above photo). I was aware that a rudder is great to stop weathercocking but when lifted can cause weathercocking itself by acting as a small sail. The Quality Kayak rudder I purchased had a very wide aluminum blade. This had a noticeable effect in strong winds so I decided to make myself a high aspect rudder (longer and narrower). The new wooden blade has the added advantage of reducing the amount of drag when in use. I also think it is more effective in keeping the kayak straight, and because it is longer is less likely to come out of the water in choppy conditions.

Making the Blade

To make the new blade I used the old one as a template. This rudder system has 2 discs on each side of the blade which the lifting lines wrap around. Each disc has hole for an axle and a tab to engage the blade. This meant the blade had to have 1 large centre and 2 smaller exactly placed holes above and below it. I used some leftover 4mm ply as the core of the blade.

I traced the outline of the aluminum blade onto the ply, marking the positions of the holes. I then redrew the rest of the rudder to the length / width I wanted and cut it out with a jigsaw and drilled the holes. To start an airfoil shape I rounded of the top edge of the blade (the edge that will part the water when in use) and sanded a knife edge on the underside. After a general sand, I wetted out the ply with epoxy and when dried, glued on the veneer designs

The blade has 3 layers of 6oz cloth on both sides. This was the time consuming part since I had to wait for a layer per side to dry tack free before flipping it over and doing the other side. The wetted out cloth was allowed to overhang both the blade and work bench on the rounded edge of the blade so that the cloth naturally followed the curved edge. Once tack free each layer was trimmed to size with a craft knife.

A final sand down to 200 grit and a few coats of UV protective varnish finished it off. If the blade is too thick to allow the control lines to lift / drop the rudder then the 2 plastic discs can be sanded down until the thickness of the control lines is reached.

A major disadvantage of a fiberglass rudder is that it can not bend and will break if forced sideways on a rock or the beach when surfing. Since a rudder is not essential and since I have never broken or bent a blade yet (lift it up before surfing into shore) I'm willing to take the risk for the performance advantage the longer rudder provides.

The rudder block caused me a few headaches. The blade hit it with such a force that it would chip the wooden block. I even made one with 4 layers of glass to protect it, only to find the fiberglass delaminating after a few weeks of use. The problem was solved with version 3 when I sandwiched a PVC insert. The blade hits the insert first (which is 2mm proud of the surrounding ply) and it is strong enough to absorb the impact with out chipping.

Since epoxy will not adhere to PVC, I shaped it as in the diagram above. The epoxy fills in between the two pieces of ply and stops any movement of the PVC insert. Two side strips of ply 4mm x 4mm where added to the sides to cover up the mess. After six months of use there is no sign of movement or damage to either the block or blade. The foot of the block was cut from some pine which matched the Gaboon ply remarkably well.

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