The coolers formerly known as Icey-Tek are now being marketed under several different names, one of which is the Yeti Roughneck.
http://www.fishing-catalog.com/iceytek/index.htm
BoatersWorld markets them under their OuterBanks brand.
http://www.boatersworld.com/product/479670119msk.htm
I have a pair of Icey-Teks, a 40 qt which is my 'beverage cooler', and a 70 qt which is my 'fish cooler'.
The 40 qt is the perfect size to keep on the boat, and I've used it for 3 full seasons now keeping beverages cold all season long. Pretty nice to stop by the boat on the way home from work to make sure all is well...
and have a beverage before going home. 8)
The key to keeping ice for days is simple. Load up the cooler with beverages and fill with ice. The less dead-air space you have in the cooler, the better. Then place a towel over the cooler to protect it from the sun and help insulate it.
Beyond that, resist the urge to drain off all the water each time you top off your ice. That cold water displaces air and the ice-cold water helps to keep the beverages colder, longer.
I have a 'beverage refrigerator' at home with an ice maker in the freezer. During the boating season I'll stockpile ice by putting it in plastic grocery bags and store it in the freezer. Every couple days I'll take a bag to the boat (I'm only a mile away) and top-off the cooler. The plastic grocery bags then become 'boat trash bags'.
Even in the heat of summer, ice will last in my Icey-Tek for 3 to 4 days (or more).