Could you describe this rudder again in a different way? I can't quite visuallize what you've done. I'm coming up with essentially a box kite hanging down with strange funnel cones everywhere. I'm very interested in what it really looks like.

> Some months ago, focusing more on how it would look than how
> it would work, I built an internal rudder that when deployed, projected
> perpendicular to the hull, thus working as a brake instead of a rudder.
> (And not very well at that)

> Still focused on aesthetics, but more knowledgeable about what
> constitutes turning momentum, I’ve since built another integral rudder
> that actually works. Essentially, 3.5” down from the sheer line, I
> cut out a 4” X 11” section from the stern of my 20’ Pygmy Osprey double.
> I installed a bulkhead 3” forward of the cut out, and for strength,
> filled the keel and sheer sections aft of the bulkhead with epoxy/silica.
> I enclosed the top and bottom of the cut out “rudder” section. To
> avoid turbulence when deployed, I fitted a matching conical piece
> to the open end, then drilled the centers of the circles and the reinforced
> sheer and keel sections for the full length rod that would rotate
> the rudder. Once everything was fitted, the rudder matches the hull
> lines with about 1/16 inch clearance at the top and bottom The vertical
> cut in the hull very closely matches the rudder while the conical
> section rotates inside the hull. The opposite side stays flush to
> the hull due to the matching conical shape. You can see it's a rudder,
> but it conforms perfectly to the lines of the boat. (Similar to Dagger’s
> Sitka rudder, but stronger due to the keel, and, I believe, more effective.
> : Sea Kayaker review-Oct ‘97)

> At prox. four knots, with the rudder fully deployed to 35 degrees,
> the Osprey turns 90 degrees in less than twice her length and feels
> a bit like a car’s rear wheels breaking loose in a power skid. This
> is great, but there is an unanticipated effect. The glide of the Osprey
> is now so much better, I wish I had some way to quantify the difference.
> Even my ethereal wife, who has been known to obliviously paddle with
> her blades reversed, said, “Tom, what happened... why is it paddling
> so easy?” Too subjective, I know. I understand a normal flip up rudder
> causes some turbulent drag, but the change doesn’t simply feel like
> less drag, it feels qualitatively less. A skeg’s drag is used to correct
> for weathercocking. Is it that significant? Short of expensive tank
> testing, does anyone know of a way to measure/calculate the difference.
> It’s obviously not a real problem, just pleasantly perplexing... like
> my wife.

> Thanks,

> Tom