You want to make a hit with others on the cruise?

Get a styrofoam cooler. Take a second cooler and cut the styrofoam so it makes it double walled. Buy 20 lbs of dry ice, wrap it in a newspaper and put a a couple of quarts of Hagan Daz inside and tape it closed. It's good to punch a small hole in the top and cover with tape so it can bleed the air as the dry ice melts. It should last almost a week (if you're concerned about how long it will last, Hotwire has a digital temperature gauge with a 4' sensor for $10.00. You can monitor the inside temp with it. Always good to have on a boat and $10.00 is a great price. Hotwire doesn't list it on their website so it's hard to find if you don't know about it. Call John and ask for the $10.00 digital temp gauge. John at Hotwire Ent. 727 638-7417

here's the page http://www.svhotwire.com/catalog/advanced_search_result.php?keywords=digital&x=0&y=0

When you have one or two days left bring it to a pot luck or get together and share. You'll be the hit of the cruise and they'll wonder how you did it with the small boat.