How do maximize ice chest efficiency for a five or six day trip? The first thing is to have a good quality cooler. This does not mean that you have to spend hundreds on a cooler. Good coolers can be had for under $100. The first thing you will want to add to your cooler is a piece of closed cell foam pad to the cooler. This is the material that the cheap sleeping pads are made from. Cut a piece that is the same size as the cooler lid. It is placed directly on top the food/drinks/ice. This adds a layer of insulation directly over the ice and food. This will make a big difference in the efficiency of the cooler.
The next consideration is what to use for ice. The best option is solid block ice. This ice is more or less clear where the compressed ice looks like it was made of compressed ice chips. The problem here is most places sell compressed block made from by-product ice chips. Compressed block ice has much more air within it, than the solid block ice. Solid block ice melts much more slowly. Don’t use ice cubes for keeping a cooler cold for a long trips as these melt faster than other types of ice.
What is the ice to food ratio for the cooler? This is a tricky question. This will depend upon a few things. How many coolers are you bringing? If you are brining only one large cooler, you ratio will need to be 1 part ice to 1 part drinks and food for a five day trip. Good luck trying to fit it all in. If you are bringing more coolers there are other ways of keeping your stuff cold for prolonged periods of time. On my most recent trip we brought three coolers for a six day trip. We had one medium cooler full of block ice and a couple bags of cubes to add to drinks. This was topped off with 5 lbs. of dry ice. The dry ice will super freeze the ice and it will stay frozen for a very long time. When my block ice in my big cooler got small, I put the blocks from the medium cooler into the large cooler. The third cooler we used was a medium size for beverages only. This was half full of block ice and half full of drinks. The idea here is to not have to open the food cooler as often, and keep the perishables cold. Our large cooler was for perishable food only. We pre froze items that were freezable to help maintain the temp of the cooler. We used about 1/3 of the area of this cooler for block ice and 2/3 for food.
It is also important to drain off the water in the bottom of the cooler twice a day. This will keep your melting rate at a minimum. You also want to make sure your coolers are not left in the direct sun. If you don’t have shade, emergency blankets are great at shielding the coolers from the sun. Just make sure the silver side is facing up.