Congrats on the new boat Loaf! Rather than buy ice, you should work on strategies for doing without. Remember, there was no such thing as refrigeration until the 20th century. Somehow civilization survived without it until recently.
I survived without refrigeration for a year living on my boat in much warmer climes than Annapolis in the winter. Most foods will keep without refrigeration, some for a long time. Eggs, cheese, butter, condiments, sandwich meats and beer do not need refrigeration. Even milk will keep for several days without.
Hopefully others will chime in with more tips on doing without refrigeration. But in any case, it's pretty cold down here in Virginia tonight. More so in Maryland I'm sure. So your ice quandry should be moot soon.
Gemini Catamaran Split Decision