That is a near impossible question to answer with what has been given. Why do you need a new prop? Was the boat running good with the current prop before whatever happened that is causing you to replace it? While it may be a PITA, you need to know what pitch and diameter prop is currently on the motor. You should be able to trim the motor all the way up and get to the nut holding prop on with minimal pains. Worse case, you take a little dip in the water to do this.(given you are in the NE, you might want to do this sooner than later since the leaves are already starting to change!). If you can get to the prop nut and remove it (without dropping it in the water), then carefully slide prop off. It will show you on the end of prop what it's diameter and pitch are (ex. 14 3/4 X 15). From there you can decide what prop you want to replace it with. The diameter must be the same, however you can adjust pitch depending on what you want to gain/lose in terms of RPM's. For every inch you drop the pitch, you will gain about 200 RPM's, in the like manner, every inch you up the pitch, you will lose about 200 RPM's. So if you are trying to gain some RPM's to get a little more top end, and are not currently above the motors recommended max RPM's then drop your pitch a bit. If you were happy with the way it was running, but damaged the prop, simply replace it with the same pitch and diameter.