This topic includes the making and installing of a rudder winglet on the Hobie sailing rudder. Applicability is for sailing, boat wake/ downwind running and any Adventure Island applications.
Benefits include better rudder authority under high speed when rudder deflection or side loads occur. It does not improve rudder handling at normal kayaking speeds, especially in mild weather conditions. If your rudder is doing all you want it to do, then this project would of little more interest than, say, a gripping suspense novel. So lets get started.
Note: In some of the pictures below, you may notice other rudder modifications. They are not a part of the winglet project and may be ignored.
The winglet measures about 3 1/2 in. x 1 1/2 in. It is made from Plexiglas approximately 1/8 in. thick, but you can use any scrap material you find suitable and workable.
I strongly recommend building two at the same time (for the very small additional time it takes) for the following reasons:
1. It's much easier to handle and work with the larger piece
2. Better strength when you are cutting and shaping the slots
3. If you break/mis-cut one while building, you have a spare
4. If all goes well, your new best friend will want one!
Materials and tools:
7" x 1 3/4 (+/-)" x 1/8" suitable plastic or Plexiglas
epoxy glue (I used a fast set for set up, then JB Weld for final gluing), pencil, ruler or tape measure, masking tape for lay-out, coping saw or equivalent, thin file (can sub. folded sandpaper, emery board, etc), assorted sand papers (med., fine grit) and wet/dry sandpaper (med or fine).
1. Remove rudder for ease of handling.
2. Draw vertical reference line from notch on starboard side of top to extreme tip of rudder (see pics #1 and #2).
3. draw horizontal line 13 1/4" from top shoulder of rudder as shown in pic #3 (both sides of rudder).
4. If using another location or rudder, measure and mark thicknesses at 1/4" intervals along the horizontal line. For the large sailing rudder, the measurements are (from front to back): 0;1/8;5/32;3/16;3/16/3/16;3/16;--;5/32;9/64;1/8;7/64;3/32/--. See pic #3 for clarification. Note the winglet should not run all the way to the front of the rudder.
1. place masking tape over your winglet blank and draw a center line and 1/4 " grid pattern (pic #4)
2.Carefully transfer your rudder thickness measurements to your blank as best you can. After rechecking, connect the dots.
3. Using pic. #4 and your grid as a guideline, mark symmetrical reference lines to create the outer shape; connect the dots and smooth.
Cutting the winglet:
1. using a coping saw (jig saw, band saw, etc) carefully cut your slots for both winglets.
2. With a thin file, folded sandpaper, etc. smooth and enhance your slot, fitting frequently on the rudder for reference (slip it on from the bottom). Don't rush this phase.
3. extend and customize the back of the slot to fit your rudder's curvature. The fit will not be perfect, but not to worry -- epoxy will take care of any gaps. Don't force the winglet or you may stress the small area behind the rudder.
4. When satisfied with the final fit of both winglet slots, cut your outer shapes (pic #5)
1. Using a combination of filing and sandpaper, taper from the center out in all directions. Ideally the top edge will be somewhat mounded and the bottom flat, the edges rounded, except for the back edge which should be left blunt. Pics # 6 and #7 apply.
Attaching the winglet:
1. I'm recommencing a quick set epoxy or glue to tack the winglet in place. You may have to hold it until the glue sets. It is important that the winglet is horizontal and not set crooked from side to side. Your reference line may disappear (as mine did) under the glue line, so you should draw parallel lines on both sides +/- 1/8" from your mounting location.
2. When tacked, you can apply the JB Weld (or whatever you want to use for a permanent bond). Let it set-up then use your wet/dry paper to apply the finishing touches (see pic. # 8 & 9).
Finally, here's what it looks like mounted in the stow position. You may fashion a cushion so it doesn't slam against the deck, but I haven't found it necessary. Note only half the bungee goes over the rudder to put less pressure on it.
That's about it! Hope you were able to stand the suspense, or at least stay awake. Don't forget to let your friends know you have an extra!
For more discussion on winglet characteristics and performance, see:
http://kfs.infopop.cc/eve/forums/a/tpc/ ... 2761090753
For more info on the Adventure Island rudder modification, go to: