OK I`m ready to lay down some cash for a new FF. After picking out a model I need to decide which transducer to get with it. One says dual freq. for maximum saltwater preformance the other says dual beam for max coverage. I don`t need a ducer that penetrates 1500ft. I want to have as big a cone as I can get to see more bottom in the under 50 ft depths I usually fish. Will I be able to get away with the dual beam which says ideal for freshwater or do I have to get the narrow beam dual freq ducer because I`m putting it in the salt?