Coolers and Dry Ice

[Mark Prouty]

Dry ice is frozen carbon dioxide. A block of dry ice has a surface temperature of -109.3 degrees F (-78.5 degrees C). Dry ice also has the very nice feature of sublimation -- as it melts it turns directly into carbon dioxide gas rather than a liquid. The super-cold temperature and the sublimation feature make dry ice great for refrigeration. For example, if you want to send something frozen across the country, you can pack it in dry ice. It will be frozen when it reaches its destination and there will be no messy liquid left over like you would have with normal ice.

-109 degrees F

How do you keep the beer from freezing?
Where would one get dry ice?

Thread has been interesting. First time my son has learned of the dry ice concept.

I thought those were tomato plants.

[Frank C]

... Im still not convinced this CO2 is an asphyxiation hazard, but I do confess if I brought dry ice on board....I would add a CO2 level detector to my safety gear.

Stephen,
I'm with you ... dry ice seems a terrific, energy-free, short-term solution to the problem of refrigeration on a small boat. Seems to me that it just needs careful sizing at outset, and some prudent handling. I also agree that a CO2 monitor is a very valuable safety item. You & Moe (of scientific bent) reveal that this stuff does a significant volume of off-gassing, and my cooler is relatively airtight.

If this question is slightly daft, pardon my cluelessness ... but as Kevin asked earlier, what's the argument against plumbing the cooler's draincock to a thru-hull? As long as the lid is secured with a couple of velcro straps, seems to me the gas will push any melt water out the drain, along with the excess CO2, right? As long as one can avoid icing-over of the drain cock ... sounds like lemonade from lemons.
So, where's the problem?

[Frank C]

Okay - that makes sense since we're beginning with minus 109 ... so everything stays frozen, drain can remain open to a thru-hull, gas will push out & overboard. Guess the point is - too much of a good thing.

I've been using those "ice cube blankets" acquired at a boatshow. In concert w/ them, wonder if just a small quantity of dry ice would permit stratification - cold at top, down to frozen at bottom?
* Is dry ice available in one-inch thick sheets?
* If a dozen sheets were kept in a separate small cooler, would they keep longer?
* Could they be moved one each day to a working cooler, to keep it a little less cold than frozen?
* How costly is dry ice?

(Still slightly daft).

[Sloop John B]

I think I got my tongue stuck to a chunk of dry ice when I was a kid.

There are all kinds of plastic containers. We use the Indian River grapefruit juice containers. After you pour the juice out on top of your gin and ice in a salt rimmed glass, you clean it and fill it with water and freeze it.

I use the cheap Thermos cooler that came with the boat and another one like it. Ice is good for about three days. When the cubes are gone, slice off the top of the containers and pound what's left with an ice pick. That will do you for the fourth day and then it's time to go home.

[Andy26M]

When the CO2 sublimates (off-gasses), how much pressure will it generate? I think it'll be more than what the normal cooler seal would hold in, so the gas is going to vent somewhere - may as well tube it out through a vent or drain so it goes where you want it. If you have one of those stainless steel heavy duty coolers, I could even see the pressure damaging the seal or latch. (If the cooler lid was 20"x30" = 600 square inches and you built up just 0.5 psi inside the cooler, you'd have 300 total pounds of force pushing outward on the lid - something is going to give long before that I think; or you're gonna get a bloody nose when you pop that baby open).

For long term use, it seems like you could carry a compressed CO2 fire extinguisher and after several days use it to re-freeze water ice. A 15-lb. CO2 extinguisher should be able to freeze a decent chunk of ice... I don't think refilling them is that expensive, either.

For camping trips I learned from my parents to always use things like soups, chili, spaghetti sauce, etc. for the meals later in the week, and always carry them frozen. That way they act as the ice in the cooler, and you never defrost them - just don't use them until they have melted.

- AndyS

[Moe]

wonder if just a small quantity of dry ice would permit stratification - cold at top, down to frozen at bottom?

If you want stratification, I'd think you'd have to pull everything out to put the dry ice on the bottom. I would expect with ice on top, as recommended, convection occurs with cold falling in the center of the cooler, and with the warming occuring on the cooler sides, it rises there.

* Is dry ice available in one-inch thick sheets?

I'm sure it is from some sources, but you may pay more for it that way.

* If a dozen sheets were kept in a separate small cooler, would they keep longer?

I would expect so... and as they were used the sublimation rate would increase.

* Could they be moved one each day to a working cooler, to keep it a little less cold than frozen?

I would think anything near the dry ice would be frozen at or near -100F. As the quantity of dry ice varied from a fresh piece in until time to replace, there may be some contents in the cooler thawing and refreezing, depending upon what point that occurs for that item.

* How costly is dry ice?

I have no idea, but like most things, it probably varies with location.

The best use I can see for dry ice is to have a cooler for refrigerated stuff, kept cold as long as possible by water ice and as many frozen contents as possible, and an auxiliary cooler with spare ice extended by dry ice. The spare ice would be transfered as the contents and ice in the refrigerated cooler are consumed.

Frozen contents really help the refrigerated cooler stay cold longer. For example, with our Ice Cube cooler, using as many frozen water bottles as possible, with as much ice packed around them as possible, and the remaining space filled with refrigerated water, would be about as optimal a situation as I could imagine. No dry ice involved.
--
Moe

[Andy26M]

The few times I have ever gotten dry ice, they just blew it into a metal container; they didn't have a big freezer full of dry ice, they had a big cylinder of compressed CO2 and they created the dry ice as needed. In this fashion, the dry ice was not a big dense chunk like water ice, it was more like snow or ice cream.

- AndyS

[Catigale]

Dry ice is 10-15 cents a pound in Albany NY

If we use that 1 pound per day sublimation rate, we make 250 liters of gas at room temperature per day, so that would make a 50 qt cooler go up to 6 atmospheres pressure if you tried to seal it.

Moes research showed its probably an even higher number like 3-10 pounds per day.

A simple vent overboard would do the trick - I dont think I would drill in my hull, but would just throw the cooler in the cockpit at night fall.

[Chip Hindes]

10-15 cents per pound? In what quantities? Dry ice is available in most of the larger grocery stores in FL. However, it's way expensive. As I recall we paid something like $20 for a 10 lb block.

It damaged and ruined the taste of everything that wasn't tightly sealed. One of the guys had a six pack of Coke freeze and explode in his cooler. He's not a proponent.

Forget the dry ice. If you're going to be somewhere you can buy regular frozen water, say every other day, you'll be way ahead monetarily and otherwise doing that instead. If not, learn to live with stuff that doesn't require refrigeration.

[Moe]

If not, learn to live with stuff that doesn't require refrigeration.

As much as I love cold beer out on the water, I can certainly get by with any number of different whiskeys, rums, or tequila neat... no water, no ice.

--
Moe

[Tripp Gal]

We had a standard ice box on our liveaboard and used dry ice for major crossings. It has it's uses and place and we never had any problems with it if you know how to pack your icebox.

Take a 10lb block of dry ice and place it in a cardboard box insulated with crushed newspaper that surrounds the block. Tuck in your ice-cream bars in this box between the newspapers. It's a nice tread halfway to Raratonga. Drop the "ice box" into a plastic garbage bag to keep things dry inside.

Now the packing requires much planning but it makes it well worth it.

1. Remember that anything near the box (all 6 sides) will freeze, so foods you want to stay frozen for extended periods should go closest to the box. This includes putting longterm foods (like frozen meats and frozen gallon of milk for later in the trip) at the bottom of the ice box.

2. The next layer we would pack is stuff that needed to be very cool such as fresh meats, milk, and such. Remember to put the least used items near the bottom.

3. The outer "ring" includes a home for cheese, eggs, mayo, lettuce. that do well with moderately cool spaces.

This setup will last in a 3.5'X3'X18" icebox for up to 3 weeks depending on how many openings. What we recommend to new cruisers is to do a 2 icebox system so that drinks and snacky things are in a separate box and can be easily disturbed without affecting the serious food.

Just hold your breath when you dive in the box and use gloves for diving for frozen bits. Let your icecream soften a bit before biting into it as well.

[Frank C]

My question was not academic. We'll be out for five days in the Channel Islands this summer. There's no ice out there, and no gas either. Though the Igloo cooler is a 5-day version, the ice we have on Sunday will have definitely expired by the time we get to Catalina on Friday. That's not a disaster, but it's worth considering alternatives.

Nice summary TrippGal! Unfortunately, even the Igloo-70 is probably only half the size or your big boat's ice box. Moe's idea has good merit too ... dry ice could be used in a separate cooler to keep some water-ice reinforcements nice and cold for 2 or 3 days. Good ideas, Thanks all!

Upon reflection: Seems like that Mead Madness event will also be 4 to 5 days with no commercial stops - and it'll prolly be 95F out there! Hoping to be ready to go for that one too ....

[Tripp Gal]

Other than being a tad deeper it seems like so many coolers today are about as big as my "freezer" box on the old boat. It always felt like I was trying to stuff a years worth of food stores in a college desk fridge on that boat.

[Catigale]

Thanks Tripp - if a 10 pound block can last 3 weeks that puts the 'snuff out' issue to to rest....that sure seems long imho though....

Chip - i got that 10 cent per pound quote from carbonic in Albany for home freezer use in a power outage - didnt specifiy a qty.....it makes sense to me it might be a lot cheaper to buy it direct from MFG when you consider the sublimation losses in the business plan

i guess if i were trip planning I would use your number of $10 per 20 pound block unless i could get to a manufacturer direct.

Catigale

on edit - corrected brain fart on Chips price

[Tripp Gal]

While I would never accuse Hunter of making an icebox with amazing insulation power I guess they could. I doubt Warren cared that much about such a detail. Most of the "neighborhood" were experiencing the similar results though. Planned entryies into the coolers, pre-freezing some things if possible, insulating the dry ice in the box with newspaper made the biggest deal. We had a couple of folks who just threw it down in the bottom of the box but then it didn't last but about 3-5 days.