: First install a surf ski style footbrace in the cockpit. They are
: way more comfortable than pegs. I'm sourcing mine through
: Stellar Kayaks. All compression-molded carbon fiber. Light and
: easy to adjust.

: Under the hull rudders are definitely more efficient but you do
: have to mind where you paddle. Forgetting it's there can be
: expensive when you hit a submerged rock or log. If you paddle in
: big waves the under the hull rudders stay in the water more than
: stern-mounted. That can be important. For stern-mounted rudders
: consider Smart Track's Race version. The cartridge is a lot
: smaller and doesn't hang down as far as the regular version.
: That can be an issue with kayaks with low sterns (like the
: Mystery). The blade is also interchangeable with the larger
: tandem blade if you find the single-sized blade isn't providing
: enough turning moment or frequently comes out of waves. You
: don't see the ST Race version marketed in too many places. I
: source mine again through Stellar.

: I used both the Stellar surf ski footbrace and ST Race rudder on
: Lisa's "Mustang Sally" Wahoo FSK.
:
: https://www.facebook.com/media/set/?set=a.301689123249618.71543.301674333251097&type=3&l=46e254cbf8

: The BTD Sea Racer I'm currently finishing up has the Stellar
: footbrace and their under-hull rudder blades.
:
: https://www.facebook.com/media/set/?set=a.307257219359475.72440.301674333251097&type=3&l=b6ed09d7ac

Underhull rudder is also more efficient (assuming the blade is the same shape) can be smaller with less drag for the same effectiveness. End plate effect of the hull means there are less vorticies formed at the top end of the foil which rob the foil's effectiveness on a over stern rudder.

Bill H.