* reversing a short-cutoff engine is tricky, particularly a single cylinder.
* a single screwed boat nearly 40' long can be difficult to
handle in close quarters, particularly in reverse, and the Kitchen rudder provides
excellent slow speed handling since it's basically a steerable stern thruster in reverse.
* Keeping the engine running in one direction lets me use roller pumps for coolant
circulation.
Building a slip eccentric reversing gear is pretty simple; that's what I had on Otter's
first engine. Worked fine; this would be more difficult with a bigger engine but still
workable. The ability to throw the engine in reverse as a brake is handy though,
and you cannot do that w/ a slip eccentric, so more planning is required on the part
of the helmsman.
From looking at various videos of the Kitchen rudder in operation it does seem like a marvellous device. Perhaps if he'd marketed it as a vector thrust steering device he'd have had more success. The partial shrouding of the propeller that it offers should mean it is more efficient too.
The other day an old MoD mate of mine pointed me in the direction of the Voith Schneider propulsion system which the navy used on its mine-sweepers at one time. A bit impractical for small steamers but it does make the point that there are alternative ways of doing things.