Roger Long wrote:

You really should not be thinking about self steering on an 18 footer
unless it is one of those miniature keel boats with full deck and
cockpit. A sudden wind increase in a capsizable boat that is trying to
keep maintaining a relative wind direction could be very bad.



It is just exactly that, Roger.
Catalina Capri 18 - ballasted fin keel - NOT a ceterboard -
with a cozy cabin for two.