We had a Yeti and two Engels on the Grand last year, along with Igloos and Gotts. The Yeti and the Engels were half filled with good block ice from Tour Ice and then we added water to fill in the gaps and put them in a minus 20 degree walk in cooler for a week. (Nice to have a friend who manages a grocery store.) The Yeti ice was melted on day twelve. There was still ice in the Engels when we were cleaning up at home on day 17. The Yeti was smaller than the Engels and didn't fit side to side on the inside of the boat so there might have been some air circulating on the sides, but not enough to make a 5 day difference IMO. Plus, the Yeti had the meat for the last three days and so it hadn't even been opened yet, where the Engels had been opened earlier in the trip.
You had me at 'Hey, Row'