So the plans call for the rudder to be shaped into a blunt taper on all edges. Wouldn't rounding off the leading edge and tapering only the trailing edge be a better shape for the rudder? More like a teardrop or a wing on a plane. Or does a more "pointy" leading edge reduce drag by cutting through the water easier?
Here are a couple of pictures of my rough cut steering assembly. I have a lot of work to do to shape the tiller once I determine what fits me best. Hopefully I will not get kicked out of Home Depot for fondling the garden tool handles.
Tom
Oops. I missed a d in the subject line. Didn't mean to be "rude".
I think Paul has far more competitive experience to draw from, but I think in our boats it's not super-critical. Slightly rounded leading edge, I leave a sharper edge on mine but probably a nice ogive with either a blunt ot sharp entry is OK. Technically, I suspect blunt ogive and tapered trailing edge, as you stated, are probably preferable.
I just draw on a centerline and whack away with a surform and have fun...Not too scientific, but a little bit of feel does go into the shaping. Like a surfboard.
Mike
I like the airfoil effect on my rudder. Look at the bulb on the nose of ships or the shape of whales and dolphins. A nice rounded leading edge tapering to a small rounding edge.
A sharp or crisp leading edge will cause the foil to stall very quickly, which is why you always see rounded (00 NACA series) or elliptical (5 digit NACA series) shapes used on the leading edge.
A flat sided foil shape will do just fine. Round over the leading edge with a belt sander or what ever is handy. Taper the trailing edge starting about half way back along width of the blade. The trailing edge should be very crisp and dead bang straight cut. Don't not round over the trailing edge, it'll make the blade hum and vibrate, not to mention create a bunch of drag too.
Great! Thanks for the info. It's just what I needed to know.