Suggestions to Increase Secondary Stability?

[addicted2sp33d]

My wife and I use our Pelican 130T Tandem on Lake Hodges at least once a month - we (meaning mostly me) paddle a few miles every excursion.

This thing tracks about as straight as a Tim Tebow spiral, so I wanted to get a narrower kayak with a more-pronounced keel. My wife really likes the primary stability and is not a big fan of getting a narrower tandem.

So in the interest of continued adult activities together, paddling or otherwise, I am stuck trying to improve the tracking of this hull.

I was thinking of adding a rudder. Would that help, or would that be the equivalent of adding a Hobie rudder to an aircraft carrier?

Maybe some under-hull fins like surfboards?