Not transom rated but hull speed rated
Hull speed on a Catalina 27 is 6.3 knots, so jet propulsion won't take it above that speed - okay, maybe a jet might but do you really want to be on board when it does? Most sail boats in the 25 - 28 range use a 9.9 motor. On my Catalina 27 with a new 4 stroke Merc 9.9, I don't need all the power to reach hull speed. 15 horsepower is over kill for the Cat 27. It cost me around $800 to have the transom fully enclosed and the new transom re-gel coated; it looked brand new. After this you can add what ever manual or power bracket to it to take a new 4 stroke engine. And oh yes, you can more storage room in your transom locker. One big recommendation if you do this; enlarge the drainage hole to as large as you can get it, you won't regret that move either. Probably your cockpit scuttles drain into your transom locker and if that frigging original tiny hole is plugged you have problems. I installed a secondary drainage system for the cockpit scuttles, independent of the transom storage locker. I have tubes, the same as under your sink, going from the cockpit scuttle to a new transom drainage hole, exclusively for the new drainage system. The old wider hole drains whatever else gets in the transom.
