If things are like I think they are, the channels you are talking about 24 and 84 are marine operator channels that were designated by the FCC for use in public sea to shore telephone communication. They are encripted meaning you can only hear one side of the conversation. They are also ( or at least used to be) used by Telephone companies only. A lot has changed in the last few years but be aware there may be problems with these selections. That's the very reason the Non-Com channlels are all cluttered. The rest are all off limits for reports and day to day hailing and chatter.