Dry Ice, How Much?

[WanderingStar]

I'm cruising from Florida to NY, one hop, no refridgeration. I'm bringing meat and dairy in the ice box. I can get block ice and dry ice nearby. I plan to use both. How much dry ice can I add without freezing everything? Any experience with this?

[patrickrea]

If you are using dry ice, watch out for the CO2 that is released as a gas. Your ice box probably drains to your bilge and the CO2 will will drain there as well (heavier than air) and has the potential to force ALL of the oxygen out of your cabin thus incapacitating you or at worst killing you.

I would just use block ice. You should get a decent amount of time out of it. You could also use the UHT pasteurized milk that can live on the shelf until opened. Freeze some of your meat solid and then thaw on the way. It would also keep your other contents cold.

[huguley3]

I have been experimenting with both block,cubed and dry ice in my 5ish cubic foot icebox. The top is not insulated very well but the sides are. I have not had any trouble with stuff freezing unless it is right by the dry ice. Have not had any trouble with the CO2 produced either even with the boat closed up. One thing I will note is that you do not want to stick your head too far into the icebox or breath into it with the top off. The CO2 is pretty strong and I am sure you will note the same thing if you try it.

I found that 2 blocks of dry ice of around 9ish pounds would last a bit over 3 days. Each block is about a foot square and 3 inches thick. You can quickly chill a beer by putting it on the dry ice for about 45 minutes. If you forget it it will freeze solid.

I liked the dry ice better than block ice because my icebox drains into the bilge. I put a plug in the hole and just empty it in the morning to help hold some of the cold in. But spending $200 a month on dry ice has me looking at converting the icebox to a fridge. Dry ice is $1.29/pound where block ice is much cheaper.

I put the dry ice on some of those blue freezer packs that were pre frozen so if the dry ice all sublimates I still have some cooling in there. Once the dry ice is gone the temp starts to rise pretty quick without some mass to keep it cooler. Right now I am buying a couple of blocks of ice and an occasional block of dry ice. Blocks do last a LOT longer than cubes and stack more efficiently as well.

[svHyLyte]

FWIW I found that making a double layer pad of Reflectix (See Reflectix 24 In. x 25 Ft. Staple Tab Insulation - ST24025 at The Home Depot ), to fit on top of foodstuffs in our icebox, dramatically improved the longevity of block ice. While we now have a refrigeration system, we still use Reflectix pads in both the refer and freezer and our energy usage is reduced measurably. The material is inexpensive, easily cut and layers can be glued together with spray adhesive.

s/v HyLyte

[WanderingStar]

Thank you all. I'm not too worried about co2, it's a small amount of dry ice, a large volume of well ventilated space. My thought is to use dry ice combined with block ice to extend the life of the blocks. I don't live aboard, so this will be a rare expense, just for this delivery. I'll look into the reflectix.

[Bene505]

I found this site

Reflectix Product Summary

which had these details:

Product Name: Reflectix
Insulation Classification: Radiant heat reflector
Thickness As Tested: .28"
Claimed "R" Value: 8.3 to 14.3 depending on type of installation.
Actual "R" Value (at product thickness): .67
Equivalent "R" Value (per inch): 2.38

[Cruisingdad]

We just bought big blocks and wrapped it in newspaper. We tore holes in the newspaper to allow more cold air to come out. We always had problems with stuff near it freezing. I never perfected it.

How long will it last?? No way to tell as we do not know how much insulation you have in fridge, how often you open it, how tight it is, etc. All this stuff about CO2 seems way over blown to me. I have used it so many times I cannot say. And let's face it - no boat is tight. Crap, most of us can't even keep them from leaking water in - much less keep air in!!!

I say use the paper. I seriously doubt it will be as good as the product mentioned above - but it is a lot easier and cheaper and by tearing the holes in it, you can adjust the temp. Tightly wrapped, with little access to the fridge, we might get 5 -7 days out of it (of course, I have kids and it makes that really cool fog in water!!!!). We used top buy it at Walmart and then at some grocery stores... but many do not carry it anymore. After that, you are down to "water"-ice, which melts. Another way to minimize your cold air loss is to make sure the fridge is packed tightly (every air space). Some people even carry plastic bags of those foam peanuts and shove them in the empty spaces as they can. We used to cover the top of the fridge with a solar blanket (cheap) so that when opening you do not let out all the cold air.

Hope that helps.

- CD

[WanderingStar]

Thanks. Experience is priceless.

[WanderingStar]

It worked. We put 14 blocks of ice on three cakes of dry ice. We put in three fresh and three frozen meats, two and a half gallons of milk, six dozen eggs, cheese, butter, vegetables. Because the trip had breaks, we added cubes twice, but also soda and more fresh food. Twelve days later we finally added more blocks (only four). Today, sixteen days after our start, I took out three peices of the original ice. The cooler is five and half cubic feet.

[MacGyverRI]

>All this stuff about CO2 seems way over blown to me.

Many have died from breathing it in while unloading veg/fruit trailers.
CO2 residual gas is nothing to fool with.

Here's a freak, but true story, 1746 people killed in one night from CO2.
snopes.com: Carbon Dioxide Deaths