Yamaha 9.9 4-stroke
I've just replaced our Mariner 9.9 2-stroke with a Yamaha 9.9 4-stroke High Thrust. It's a tight fit and requires some minor modifications, but it works well. In fact, I'm of the opinion this motor is ideally suited to Cat 27's. Enough power to handle almost any situation with very conservative fuel consumption. To get the motor to fit I cut about 1/2 inch off of the 3/4 inch lip on the back of the lazerette hatch over the motor opening. Also, the motor cowling has a handle set into it at the top back. To clear the top of the opening for tilting the motor, this handle must be removed. This is accomplished by simply removing the four bolts in the inside of the cowling. Under this handle you'll find a small opening (vent) I fashioned a plastic cover that kept the rain out but still permitted the motor to breath through it. Space limitations and the additional weight of a 4-stroke made it next to impossible to raise the motor and lock it into place with the built in locking device. This was easily overcome by fastening a old boomvang onto the top of the motor cowling and to the lazerette bulkhead, the mechanical advantage permits even junior crew members to raise the motor and by using the built-in camcleat locking and unlocking is simple. Both Cat 27 owners, in our small marina, are using this motor, we both strongly recommend it.Best of luck to you,Echo Gulfsv SeaRaven