I'm told we have an outboard bracket designed for beachcats in our on-line store, but it is not listed on the website yet, so you have to e-mail
rick@catsailor.com directly to ask about it.
It's cheaper and more fun to figure out how to build one yourself. Rick made one once out of wood to use with a 2 hp motor, but we never actually used it because we couldn't get the motor to work.
It has been my experience that an internal combustion engine (and an electric engine) never works when you really need it. They belong to the same union as bilge pumps.
Paddles are much more reliable when you run out of wind.