Introduction: Kayak Rudder
I set out to make a simple rudder that did not cost the typical $250 but at the same time was a bit more effective than a plank on a stick. This was designed for my Ocean Kayak Prowler 13 but could be adapted for any kayak. The focus is more on the rudder design than the various different steering methods that could be used. The rudder is easily removable for transport or when not needed and has a simple single cord to raise and lower it and is sprung to prevent damage in the shallows.
Step 1: Tools and Materials
Materials needed approx 2ft x 3 ft sheet of ~ 1/4" thick ABS plastic or similar to make the rudder, yoke and side plates, some plastic or wooden blocks to make the rudder hinge, some fairly rigid plastic tubing (I used 6mm OD 4mm ID pneumatic tubing), 2 ft of 1/4" shock cord and some non stretch cable or kevlar kite string (I used McMasterCarr 8912T314 Vinyl Coated Wire Rope - Stainless Steel, Flexible 7X7, 1/16" Diameter,Yellow, 25 ft. Length $8). Fasteners and hardware to suit your yak (four 10-32 screws minimum to bolt to the back of the Ocean Kayak ). I suggest reading through this instructable and tailoring your design to use what materials and hardware you have available.
Tools required: jigsaw or scroll saw, bench saw or hack saw, files or sand paper, drill and drill bits, measuring, scribing and marking tools, pliers, allen wrench, screwdriver and wrenches to suit your fasteners. Long wire or fiberglass rods or dowels, string, masking tape to thread the tube through your kayak. Cardboard or paper to mark out your patterns on or make templates before cutting.
Step 2: The Rudder Hinge
These two components and the pin are the basis of the rudder. One mounts to the yak permanently and the other is to mount the pivoting rudder assembly on to. The drawings are what I made to suit the OK Prowler 13. The height above water and hole pattern can be adapted to suit your yaks mounting holes and shape. The width of the rudder mount needs to match the thickness of your rudder material plus a bit! I made my blocks from UHMWP plastic but these could be wood and varnished. Mark out, drill and shape using what tools you have available. A milling machine makes life very accurate and easy, hacksaw, drill and files takes more time and care. The vertical hole through the two blocks should be sized to suit a long pin you have chosen. I have used an allen cap head screw, nickel plated and have drilled 2 holes in it for a keep pin. The hole I drilled will rust in the sea so plan to replace with a cotter pin and hitch pin in the near future.
Step 3: The Rudder, Side Plates and Steering Yoke
The diagrams provided are the dimensions I used. You might be able to improve upon the design and appearance and you can make the rudder the depth and shape you desire. The only requirement is that the raise and lower cord needs to be attached within the width of the rudder and needs to clear the hinge as it rotates. Make cardboard templates and mock-up on you yak before transferring to the ABS sheet and cutting out. Drilling the holes first allows you to bolt the two side plates together when cutting and finishing the profile as a pair. The drilled hole in the yoke needs to be a close fit to your hinge pin and the open slot needs to suit the thickness of your rudder and two side plates. A jigsaw makes life easy and then finish the profile with a file and lastly after it has been fitted up and tested you can disassemble and radius the leading edge and taper the trailing edge of the rudder blade and break the sharp corners where the shock cord rubs. Drill the hole in the edge of the rudder for the raise lower cord, thread the cord in and tie a knot. The knot must sit within the width of the rudder.I used 550 paracord and melted the end to conform. Bolt the assembly up to the hinge block. Make sure the rudder pivots freely between the two side cheeks. Using nyloc nuts allows you to set the clamping pressure at the pivot. You might need to file a lead in on the inside of the cheek pates where the knot enters between them if your knot is a little wider than your rudder. Mount the rudder assembly to the hinge block mounted on the yak by removing and reinserting the hinge pin.
Step 4: Congratulations, That's the Rudder Done!
You should have the completed rudder assembly mounted to the end of your yak. Thread the raise lower paracord though the padeye on the rear deck and forward down one side. I spliced a loop on the end since a knot was too fat to run it though the existing boat hardware. Thread the 1/4" bungee through the hole in the hinge block, through the side slot in the yoke and through the hole in the rudder. Tie knots in the ends and experiment with the amount of spring force you get. It should be enough to hold the rudder down but light enough to a: spring out the way if you hit an underwater object and b: allow you to raise and lower the rudder. Note that to raise and lower you need to give a swift pull to get the rudder to change states but hold on to the tension so that once the rudder passes dead center on the shock cord you can lower the rudder in a controlled manner. Since I have yet to find an effective and compact shock cord knot so once I knew how long the shock cord needed to be, I used a plastic 1/4" shock cord ends. You can file the hooks or loops off.
Step 5: Steering Cable Tubes.
The official OK Prowler rudder kit requires you to cut a big hole in your boat to be able to access where the cables will run and then installing and sealing a cover plate. Granted this makes the job easier, I managed without needing to drill the big hole and then making a hatch to seal it up again. The steering cables will run from the rudders steering yoke through tubes to your steering assembly. You can run the cables above deck in which case leave this step out but this is much cleaner. Drill entry and exit holes in your yak just smaller than the OD of the tubes you are using. Having a tight fit will make these naturally waterproof. Experiment pulling your tube through holes made with different sized drills. To get the tube in place with the only in hull access available being the front hatch of the yak (this is not a Trident with the middle cockpit access) these are the steps I took. Threaded a piece of string into the hull from the outside into the cockpit hole. Pushed a long fiberglass rod into the hull from the rear hole. Leaning into the hatch use a rod with masking tape on the end to get the end of the string. Tape the end of the string to the end of the rod and withdraw the rod back out the rear hole of the yak. You now have a string going in one hole and out the other on one side. Important. Check that the string runs cleanly between one hole and the other and does not loop around any internal feature (in my case the rod holders). Cut the end of your plastic tube into a taper and punch a hole and tie the end of the string to the tube through the hole. Push the string and the tube into the rear hole bit by bit keeping the string taut by pulling its other end. The tighter you made the hole the harder it will be. Keep going until the tip of the tube exits the other hole. Check again that the tube runs straight between the holes and doesn't loop around any rod holders etc. Use pliers to pull the end of the tube through the hole and cut the string. I used stainless nuts to act as keepers for the tube. These were tight and needed the tapered end to screw the nut on and to hold while tightening to prevent the tube twisting. Do this at both ends and then trim off the ends. Then repeat on the other side!
Step 6: Steering Mechanism - First Attempt!
This bit is up to you to make as elaborate (adjustable pedals on rails) or something simpler. I started with something adjustable using a continuous cable run that looped through the forward deck inside a 3rd tube but the friction was too great so I simplified it to two cables and a bungee cord but still did not like the clutter it caused. This would work but I opted to try something simpler. See my second attempt.
Step 7: Steering Mechanism - Second Attempt.
This version uses a simple cross bar pivoting about a rod holder that I had installed in the center of the cockpit. (This rod holder position with the extension is ideal for trolling and reducing the amount you need to lean forward to grab the rod. I have my depth finder mounted in the one further forward.) This design is not adjustable for different users leg lengths but fits me and is removable so only the cable remains in place. Cut a pivot plate and install it in a central slot cut into the side of the 1/2" PVC plastic tube retaining it with a tie wrap. Glue an end cap on each end of the tube having made the tubes length to suit the cockpit width so the ends rest on the ledge. Make a saw cut across the corner of the end caps to fit the cable. Countersink two 1/2" end caps for a 10-32 screw and drill a hole off center in the middle to fit a piece of 6mm tube to act as a cable guide. These screw into the footrest nuts already molded in the side of the yak. Thread your steering cables through the tubes in the cable steadies on both sides and and loop it around the saw cuts in the ends of the tube. Join, tie, connect, adjust the steering. I used oval clamp sleeves to create loops in the cable ($0.19 each at Ace Hardware) around fasteners I had. I made the cable slightly short so the cables remain in tension due to a bit of bend in the pipe.
Step 8: Steering Mechanism. Third Time a Charm.
After testing I wanted to tidy up the design for when I was using the kayak without the rudder. Minor changes were made. Firstly rather than leaving the yoke on the yak all the time with the steering cables bolted to the yoke I removed the screws and attached the cable to the yoke using small S-biner from Nite ize. A key chain for about $8 gives you lockable stainless steel attachments. Small carabiners or hooks would also be suitable. Secondly the steering cables were cut and a single loop crimped on each end to hook onto the screws. This prevents the cable slip and allow the cables on each side to be pulled forward and clipped to the side cord when transporting or not using the rudder.
Step 9: Rudder Complete
This shows the rudder components removed and ready to stow. To attach the rudder, place shock cord in to the notch while sliding the yoke onto the rudder. Position rudder on mounting block and insert pin and insert hitch pin. Attach the cable to the S-biners at the rear. Attach the loops of the steering cable onto the screws on the steering bar, fit cables into the slits on the ends of the bar and hold tension as the rod holder is inserted. The pvc tube bends slightly to maintain tension. Once the rudder is installed attach the steering bar and stretch the cable over the ends.
Congratulations - hit the water and test and remember to be safe!
Step 10: Some Dxf Files
Some have asked for drawings. I have placed some here.