Tapering Trailing Edge of Skeg?

[Ron Hotchin]

My Catbird 16 has a 4' long skeg with a depth of about 6" at the stern and a width of about 1 1/2" straight back to the stern. The rudder blade is a foil about 1/2" wide and fits up to within about 1" of the rear of the skeg. Would better water flow be gained by tapering the trailing edge of the skeg to the width of the rudder blade or would this actually increase turbulance? I notice most skegs, even on pulling boats, seem to have parallel sides and a flat trailing edge. As always, advice is welcome!

[bainbridgeisland]

A 1/2" thick rudder is pretty thin for a 16'boat. This aside though, tapering the skeg to fair with the rudder should improve performance.

How much? Barely any speed difference. You might be able to feel slight turbulence through the tiller now when sailing fast. This would probably improve with a faired skeg.

[DougWilde]

One item to consider is the hardware needed to hang that rudder. The dimension mentioned about match those of Karl Stambaugh's Windward 15. You likely will need a gudgeon for the skeg. If you taper that trailing edge what will you do for hardware? Bend something? 1-1/2 inch bronze pintles can be had easily and just as easily converted to a gudgeon.
Just think it all the way through.

Doug Wilde

[Ron Hotchin]

Thanks for the replies, sometimes it's good just to bounce an idea around. The rudder blade is actually laminated from hackmatack 9/16" thick and will be glassed and epoxied. It will end up closer to 5/8" thick and I hope fairly stiff. The rudder cheeks are 1/2" okoume ply with a 3/4" spacer, so 1 3/4" width pintles will fit. It's a kick-up blade so both pintles and gudgeons will be mounted on the transom. As for the skeg, I think I'll taper it to 3/4". Again, thanks for showing the interest. Ron