Select the proper-size ice chest or cooler to fit the boat. Sometimes called beer coolers these insulated plastic containers come in a wide variety of sizes. Choose a plastic cooler rather than plastic foam for added durability.
Attach a portable bilge pump to a 5- or 6-foot-long piece of hose. Use a portable submersible bilge pump that has a cigarette lighter as a power source. Connect the other end of the hose to the cooler.
Drill a hole in the same diameter as the hose about 2 inches above the bottom of the cooler. Fit a compression coupling with a hose connection on the outside through the hole in the cooler. Tighten the coupling and seal the area with latex caulk.
Drill another hole about 4 inches from the top of the cooler. Fit a compression fitting through the hole, tighten and caulk the area around the hole. Attach 5 to 6 feet of hose to the coupler.