Hey Laker Taker I have had the Merc 15 it ran good for 6 years, the Yamaha 9hp, speed fluctuated by .5mph got rid of it after a week. I had the new Merc 8hp for almost all last season it did not run in rough water. Seen a new boat sink in Oswego with the same 8hp Merc, the guy said the motor shut off due to rough water and it did not restart. Merc has changed something about the oxgen sensor location. When any water covers(waves grater than 1 foot) that area the engine shuts off. I now have a 6 hp Honda (Classic)and it runs in any weather or rough water. Also much lighter than any other 4 stroke out there. All these were 4 stroke motors.
