Use of Dry Ice ?

[catboatwilliy]

The local supermarket is starting to sell dry ice in small 12"X12"X1" blocks. This got me wondering if anyone has used dry ice for keeping food cold on extended voyages and/or I could best utilize this product for keeping meat and other selected perishables cool. Because it is so cold, I do not think that one could just drop it in the ice box for fear of cracking the plastics. Does any one have any experience with the use this product?
Thanks,
Bill   

[Mike Denest]

I can't comment on dry ice but we got two blocks of regular ice and it lasted for two days and there was enough left of the blocks to go for at least a 1/2 day.

[Larry Robertie]

There was a similar thread on the Mass Bay Sailors list just a couple of weeks ago.  The general concensus was that the stuff keeps your food cold but it evaporates just as fast a cubed ice.  You are better off with block ice for longer lasting cool.  We freeze spring water bottles.  When they melt you have fresh water.

[David Sanner]

One technique is to use both dry and regular ice.

Wrap the dry ice in several layers of newspaper
and then put a block of ice on either side of the
dry ice.  The newspaper and ice act as an insulating
buffer so that the dry ice will last longer.  The dry ice
should keep  the regular ice from melting.

Another advantage of dry ice is that it's roughly twice
as dense as regular ice and twice the cooling power
per pound...  so it roughly takes up a 1/4 of the space
in the ice box... and you can keep ice cream if you
pack it close!

[Michael Algase]

We have used a slightly different approach for using Dry Ice.  When we cruise for more than a week, we purchase a block (~12" cube) and place it into a styrofoam cooler (think Omaha Steaks shipping coolers), and pack all of our frozen foods around it.  When we have kept it well sealed, and only open when necessary, we have had that as a freezer for over a week while underway.  We would steadily transition frozen items from there to the Ice box freezer compartment.

It is worth noting that the sublimation rate for the dry ice is a function of surface area, so if you want it to last longer, get it in as large a single block as you can.  I don't know how well it will recombine once cut to slabs, but I expect not very well. One year I purchased one block cut in half, and it never fused back together again that I recall.  Also pay attention to protecting food from contact with the dry ice.  It should come wrapped in brown paper, but we added a few layers of newsprint around it to protect the food.

If you are looking to use it in place of having a refrigerator, there is a space savings, but I'd expect you'll spend less on ice for a comparable period than you would on Dry Ice if you have the room, especially if you use block ice (again - loss is proportional to surface area).  Many great suggestions for freezing spring water jugs and having the cold water to drink off as they melt over several days.