Icom's IC-M56 marine VHF transceiver features 25 watts of output, a dual watch, multiple types of scans and more. The radio also includes 20 user-programmable memory locations in addition to the usual marine channels like the distress and emergency call "Channel 16" at 156.800MHz. The memory locations can be used to quickly call up channels that you use a lot. Writing to a memory location will reprogram the channel stored at that location by overwriting it.
Press "MR" to choose the memory function. Then rotate the channel selector to scroll through the programmed channels. Note a memory location that's empty, or a location you'd like to overwrite. For example, you could reprogram "Memory Location 19."
Push and hold "MR" until the memory location number blinks. Then rotate the channel knob to choose the memory location number you'd like to reprogram, in this case "19."
Push "Dial" or "WX" and select "USA" or "International" depending on the type of channel. Choose "High" or "Low" power. Then rotate the channel selector to choose the channel you want to program into that location. For example, choose "06." Then press "MR" to complete the reprogramming. Channel 06 will be stored at "Memory Location 19."