---

NADAguide.com says a 2003 40 hp 2 stroke Mercury weighs 204 lbs. It's probably fine for your boat. I've read somewhere on this site that Boston Whaler says the motor should not weigh more than 200lbs. I'm sure someone will chime in about how much motor the cable steering can handle. I know in the personal page section you will observe many boats with 40 hp and cable steering. It sounds like the Whaler dealership was not interested in helping you because there is nothing they can sell you. At this time of year they are probably very busy rigging motors that they sold. Where I live there are many independent shops that would do the work. With an older boat I doubt I would ever darken the door of the dealership unless I needed parts. Their focus is to rig the new boats they sell and service the boats under warranty.