Just bought 1670, have 600 watt transducer mounted on transom of 15 foot boat, need to know best additional 1000 watt transducer for this unit. This boat is beached several times a day,and has a double hull, so I plan to mount 1000 watt on a removable pole mount on transom. So I don't care what kind of mounting it uses , just need best transducer, and the 1670f is the largest unit that will fit my center console. We have been deep dropping at 800 to 1200 feet , need to find bottom structure deep dropping, so bottom definition is probably most important. Fishing in Bahamas if that matters. Thanks for any advice.