Jump to content

Ice Box Design


Howard

Recommended Posts

I'm in the process of building a "practice" ice box, that will be used as the prototype for eventually building one into a boat. Goal is to have a super insulated box that if used carefully, might keep perishables safe for a week or two in 80 to 90 degree heat.

Basic design is around 1/4" plywood box, glassed on the inside and epoxy coated on the outside. At least 6 inches of two part polyurethane pourable foam, 2# weight, with another exterior containment shell of 1/4" plywood. Size is about 14 inches square, inside dimension, with an interior depth of about 25" to 26". This will allow two stackable milk crates on the inside for holding jugs or block ice on the bottom, and the contents of a full milk crate above the ice.

Is there a "best" design for the drain and lid? I have several ideas for both, but feel no need to re-invent the wheel by trial and error if there is already a "best" design.

Link to comment
Share on other sites


Option A for my drain design is roughed out in this photo:

IMG_2941.jpg

Photo is not exactly right, as the side drain outlet will drop to the bottom of the box (flush to the inside edge) and bottom of 2nd loop will be below the level of the box. Not much, just an inch or so. Plywood block in photo is 6 inches, about the same thickness as the insulation will be. Two part poured foam insulation will engulf and encapsulate all these loops.

I've heard two versions of melt water theory. One is to retain the melt water in the box. It is cold and retains a thermal mass of "cold". The other version says to get rid of it as it will continued to melt your ice and ice won't last as long.

Option A retains the melt water. Unless you close the drain valve outside the box, melt water will rise to the level of the loop, then begin to drain out. Top of the loop is the same height as the top of a milk crate, which will be inside the box. A second box stacked on top of the first will leave food elevated just above the ice and melt water. With plans to have the bottom of the box above the water line of the boat, this leaves the loop open to drain overboard with no involvement of the crew. In theory, this puts a vertical loop in the system to prevent cold from seeping out (cold air sinks) and isolates any warm air in the line from the cold of the box. More so if the hand valve is closed. If you want to drain the box completely, dump a bit of extra water or ice in the box and a flow will start, priming the line and creating a syphon to drain the box almost to the bottom. A bit of water would be left in the bottom when the syphon breaks. It would have to be sponged up.

Option B is much simpler and depicted in this photo:

IMG_2943.jpg

Just a 90 degree elbow into the bottom of the box and a straight pipe out out the side. Valve at the box end is a simple rubber cork to plug the drain. However, this method allows cold air to drain out, unless that line valve is closed. If you skip the rubber cork and cold water is allowed to get to the line valve outside the box, then heat can also get to it and work it's way back into the box, causing more melting. Option B will allow you to drain nearly 100% of the melt water.

Option C is a setup similar to Option B, but draining to a foot pump, going to the galley sink. Personally, I'm not a big fan of using melt water from the ice box. General assumption on my part is it's contaminated with food and bacteria and not fit to use for much of anything.

Option D is to build the inside of the box a bit larger, then permanently install something like a Beckson bilge pump, and hand pump it to the galley sink. A bit more work, but no drain to leak or drain cold air from the box.

Any other ideas?

Link to comment
Share on other sites

If you're going for super-insulated, I'd suggest a bilge pump to get the water out. If you install a drain at the low end of the box for gravity fed water drainage, it compromises the insulation at that point and reduces efficiency. I think the best solution is to mold a small drainage channel and well in the bottom of the cooler, form-fitted around the intake of the bilge pump so that virtually every drop will be sucked up by the bilge pump if you wish to use it to totally drain the cooler interior. That way, after a trip you can pump out the water and then leave the lid open to let the last little bit of water evaporate. Another possibility would be to use a gravity fed drain that is a removable screw-out plug (totally watertight and that screws in flush), which could then be covered on the inside or outside by a insulated cover to prevent the plug from reducing the insulation efficiency.

Are you planning 6 inches of foam insulation on all sides? I would think that would eat up a lot of space. I've thought about building one myself, but I would want to keep the insulated wall and floor thickness to three inches. Is there any super-insulating foam that can be used for this? The Coleman Xtreme coolers are only about 2" thick in their walls, but some of them will easily keep ice for five or seven days with proper packing techniques and pre-frozen food items. I don't know what kind of insulation they use, but beefing it up another inch of thickness ought to extend that performance to 8 or 10 days, which would be plenty for my needs. Perhaps you're thinking of even longer outings though?

By the way, I've always had better performance from coolers if I minimize opening the lid and retain the meltwater. That water stays mighty cold and seems to keep items cooler as a result, though whether or not it melts the ice faster (technically speaking), I can't say. I've never tried to measure. I just know the coolers I've used stay cold for longer overall if I leave the water in.

Link to comment
Share on other sites

  • 3 weeks later...

I had not found such a site, and I looked. One of the links from there was informative......

http://www.sailnet.com/forums/cruising-articles/20431-art-ice-ing.html

That would suggest you want to drain melt water out as you go and NOT let it accumulate. So much for our theory of retaining the mass of cold?

My experiment has progressed to this point:

IMG_2963.jpg

This drain system does work and once the water level reaches the crosspiece, water drains out. Prime it full and a syphon is created and drains it all down. This drain enters from the side, so when the syphon breaks, about 3 quarts of water remains. If the ice melt theory is right, this needs to be cut way down to get far more of the melt water out sooner. An inch or two at most.

I also got a copy of Calder's book and in true Calder form, the vast majority of his material on cold storage was devoted to mechanical refrigeration systems and almost nothing on ice. Still, a lot of the material on insulation amounts and types made sense. Calder's drain sketch showed a bottom drain with trap, similar to a common sink trap, as a means of blocking the cold air from draining out. Presumably, this also blocks warm air from infiltrating in. There may not be enough conductive heat entering through the insulated drain pipe to matter, especially if the drain is PVC. But such a trap in a bottom fitted drain also traps or pockets water that is not drained out. It would still be there to freeze in the wintertime. My syphon loop leaves water in the box, but not hidden in a line. To lay up the boat for winter, you can sponge it up out of the box.

I've also ordered the Pardey book that explains design and use of ice boxes. I find the Pardey's theory of simple, robust systems an interesting contrast to the complex, mechanical Calder solutions. As I lean in the direction of simple, I'm looking forward to reading what Larry has to say about how to build an ice box.

BTW, I will also mention that in the Calder reference, his recommendation goes to foam sheets (blue board) vs. poured in foam, which he indicates has two flaws.......voids in the pour, which allows air infiltration (heat gain by convection) and is moisture permeable, which means moisture will be trapped in the insulation, resulting in heat transfer into the cooler by conduction.

I would have questions about the blue board. I see no mention of it's ability to support loads, nor concerns about it breaking down if exposed to solvents. In my experience, any exposure of these foams to an oil based paint (Brightsides for example) will cause it to break down....even if glassed over first. I've seen it happen. Poured foam will support the amount of weight of an icebox and is resistant to all these solvents.

Lastly comes the idea of adding heat reflective additive to paint used outside the box. This one pops up in most searches:

http://www.insuladd.com/

If this works as advertised, we may want to consider it for all topsides and deck paints as well.

Link to comment
Share on other sites

That would suggest you want to drain melt water out as you go and NOT let it accumulate. So much for our theory of retaining the mass of cold?

Well, as far as I understand from my own experiences, the ideal scenario is to retain the meltwater, but to keep the ice in an elevated position so that it is not sitting in contact with the meltwater. The problem with meltwater (i.e., the reason some say to extract it) is that when it contacts the ice, it speeds up how quickly the ice mass melts. As that mass reduces, so does its cooling capacity and duration. If, however, you keep the ice above the meltwater, then I think the problem is eliminated and keeping the meltwater in actually helps preserve some of the cooling capacity which would be lost if the water is drained.

I don't know the science behind it, but I have definitely found that my Coleman Xtreme coolers seem to work better (i.e., stay colder for longer) if I pack ice on the top of the food items, while allowing the food items themselves (in sealed containers/packaging) to sit in the meltwater. The ice chunks on top of the food (out of the meltwater) seem to take longer to melt, while the food items seem to stay colder when they are partially or fully immersed in the cold water. On the other hand, if I extract the meltwater, the ice seems to disappear faster. I don't know how much of a difference since there are other variables that are hard to control unless you're running some kind of lab test (i.e., how often you open the lid, how much time it takes to locate the desired item, how large the ice blocks/chunks you use, how much food I pre-froze before putting it in the cooler, etc.); however, I would guess that, on average, my cooler stays colder for at least 6 or 8 more hours (over a 3 day period) if I retain the meltwater and keep the ice near the top of the cooler. My best guess for why this occurs is because on my cooler the drain is at the lowest point, so as I let the meltwater out, perhaps it is allowing valuable cold air to flow out also, raising the cooling demand on the remaining ice when the lid is subsequently opened (i.e., more space for outside air to now enter). This is supposedly why chest-style (top opening) freezers are more efficient than those with a side-mounted hinged door... each time you open the door, cold air spills out the bottom and gets replaced by warm, moist air. With meltwater, it stays cold and won't be unsettled or warmed significantly by a quick opening of the lid--at least not nearly to the same degree that cold air can be disturbed by that same action.

I think you're prudent to build a test version before installing one on the boat, as then you can just run some tests to see which way is better. Keep in mind that my observations have all been casual and therefore highly subjective. I have never actually timed how many times and how often I opened the lid, or using a thermometer to verify actual temperatures, or any of the other things that can make a big difference in actual efficiency. But I do feel reasonably confident that my experience does not fully support the theory that it's better to remove the meltwater. I think it's more a case of keeping the ice out of that water... which could be accomplished by building an ice holding compartment near the top of the box or putting the ice in a plastic container (with drain holes) that rides on top of the food items.

Kind of an interesting subject the more I think about it... now I'm very curious about the science of all this. I look forward to hearing what you discover.

Link to comment
Share on other sites

For this test, I have decided to add a bottom drain with loop and will cut down my syphon loop above, leaving about 2 or 3 inches of melt water in the bottom. The interior of this box is about 14 inches square and if left to the level of the drain as shown, the box holds several gallons of water. That is a lot of weight to have sloshing around and riding on the insulation. But by having both in the same box, I can measure melt water both ways. Not entirely scientific, but should work well enough for my purposes.

One thing I'm pretty sure of is a square shape results in the most internal volume for least amount of surface area. As per Calder, as you increase the amount of insulation, the R-value benefit from each additional inch is halved. It all tops out at about 6 inches being the greatest benefit. Beyond that, the diminishing returns isn't worth it. This box will have about 5 1/2 inches.

Next problem is the lid. Building an access lid that doesn't conduct heat in. Best materials for durability and R value would likely be pvc or an injection moulded plastic like the stuff coolers are made of. Most of the home built versions use glassed and painted plywood or glassed over foam board with foam seals. Turns out fiberglass is a good conductor of heat, seals or not. Wood conducts heat too.

May give Lexan a look as a durable surface for the foam board top and lid. Lexan has a decent R value of about 2.5 or so. Thinner being better.

Link to comment
Share on other sites

The value of the melt water as a cooling material/cold plate is minimal. It is barely below the temperature of the air in the ice box. The considerations needed to keep ice above it complicates the design of the interior of the box as you need a rack for the ice and now the ice is above and in the way of getting to the food/drinks. A drain with a trap in it eliminates air getting in through the plumbing and means all water can be drained out immediately. A spigot can be added if you want to utilize the drain water for drinking. This does however mean you have to keep it clean all the time and most find it tedious to do. Being able to get food or drinks out quickly seems to me extremely important. Ice on the bottom means it is never in the way.

Link to comment
Share on other sites

The math for this project is kA(To-Ti)/D where k is the thermal conductivity of the material (inverse of R value, I think), A is the surface area, To is outside temp, Ti is inside, and D is the thickness of insulation. I wonder what the R value or conductivity of your expanding foam is? I'll bet purpose-made insulation would be way better. Because you want minimal area, the closer to a cube you are the better. (Spherical is better still, of course...) Melt water should be retained if practical: it has the power to absorb a calorie of heat per cubic centimeter with a change of only 1 degree C. (That's the definition of calorie.) That's a lot of thermal inertia, and there is no commonly available material that even comes close to that. (We use melting ice in coolers because it absorbs 40 calories per cubic centimeter in the act of changing phase.) I can see how immersing the ice in water would be a problem, though, since water carries heat much more effectively than air, so means that the air in your cooler isn't able to provide its own contribution to insulating the ice. I would avoid any plumbing that compromises your insulation, so I'm with Wes on a hand bilge pump and a sponge.

Link to comment
Share on other sites

The considerations needed to keep ice above it complicates the design of the interior of the box as you need a rack for the ice and now the ice is above and in the way of getting to the food/drinks... Ice on the bottom means it is never in the way.

Hirlonde makes a good point. For efficiency, I assume you'll be using large blocks of ice. I wasn't thinking of that. In my coolers, I use smaller chunks of ice, which aren't really in the way on top because I can plunge my hand right through the ice, identify the food or beverage item by feel, and pull it out--all in a quick movement that requires the lid to be open only a short time. With block ice, though, it probably would be impractical to have it on top unless there is a very large dimension to the upper portion of the chest. If the chest is very large (length x width), it might be possible to make an ice compartment for one-third or half of the top, and to make an access lid the size of the other half or two-thirds of the top. The smaller the access lid (keeping convenient access still in mind) the more efficient the icebox should be because there will be less opportunity for loss of efficiency each time you open it. Even then, depending on the size of your ice mass, it might get in the way if it's on top as Hirlonde rightly warns.

Regarding the meltwater... I could be wrong, but my theory for why it seems to help with the cooling in actual experience is because when you open the lid, the cool meltwater cannot be wafted out of the cooler by the lid-opening action. This means it keeps the cool in, whereas the air in the cooler does stir a bit when open the lid, and admits warm air to enter, placing additional thermal load on the ice. That makes sense to me logically, and lines up with my experience that retaining the meltwater ultimately permits a few extra hours of cooling as opposed to emptying it. But I don't know the science of it, so it may be that some other variable is actually making the difference, of which I'm simply unaware. I do agree though that the ice cannot be allowed to sit in the meltwater or it will dissipate faster. Thus, if you cannot make a raised shelf for the ice, then you probably do want to extract the meltwater.

Link to comment
Share on other sites

Jeff: As near as I can tell, the R Value for the 2# (weight per cubic foot of foam) two part poured foam insulation is 6 to 7 (I've found both numbers). I'm assuming an R value of 6. Your comments about the thermal mass is what prompted us to assume retaining melt water would be better than draining it out. Why dump ice water? It would absorb heat....or so it would seem.

On the ice/meltwater ideas, it also depends on what you are cooling and how you manage the box. Beer or other sealed beverages can slosh around in ice water and stay "ice cold" and become part of the thermal mass. On the other hand, meat, eggs, butter, fruits and perishables are not something to immerse in ice water. They would be kept up out of the water, but to be of any value, these items need to be kept in close proximity to the ice, which appears to offer temps in the 40 degree range inside a box. One of the things I intend to measure is the temperature profiles as you elevate above the ice. Block ice apparently lasts about 4x cubes or crushed, at least if you are draining melt water. You can buy blocks or make your own.

On the open lid ideas, Calder now advocates easy to access side opening ice boxes (those with mechanical refrigeration). He says the heat loss / transfer is not that great over a top loader. In his system, the real damage comes not from heat gain, but from humidity and moisture that condenses and limits the efficiency of his electric system. That is not a problem with a true ice box. Almost everything points to a well insulated top loader for ice boxes.

Link to comment
Share on other sites

On the open lid ideas, Calder now advocates easy to access side opening ice boxes (those with mechanical refrigeration). He says the heat loss / transfer is not that great over a top loader. In his system, the real damage comes not from heat gain, but from humidity and moisture that condenses and limits the efficiency of his electric system. That is not a problem with a true ice box. Almost everything points to a well insulated top loader for ice boxes.

That's interesting... I would still think a top loader would be better for electric systems also, though I suppose part of the rationale might be that the coldness of the cooling unit is not significantly affected by either access (door or lid) design. Nonetheless, all that cool air is still spililng out of the unit when the door is opened, which is not only losing its cool so to speak, but also therefore admitting in more of the humid (and warmer) surrounding air that Calder worries about. I would definitely still expect a loss of efficiency as a result (and more drain on the power supply), though I would understand if he reasons that this is an acceptable loss for the added convenience of a front door.

I agree about the icebox approach... everything I have read has said, unequivocally, that a top-loader (lid) design is the best way to go. If I were building one, I might even consider making a 2" rim all the way around the top (framing the lid) to act as a "lip" or "rim" to further discourage air movement when the lid is opened. I don't know if that would help or not, but it might. I remember I once put some dry ice in a cooler and I noticed that when the lid on the container is opened, there is a suction effect that wafts some of the cold air up and out of the box (you could see it happening because the dry ice is so cold it sort of "smokes" when it mixes with the warmer air). Since I've been thinking about this thread, I've begun to wonder if a lip of the sort I described would reduce that effect in a significant enough way to improve efficiency.

Link to comment
Share on other sites

If you think about it. If you have a box relatively full of cold food, you simply do not have much air in the box left. Therefor opening the box allows little air to spill since there is little air in the box relatively speaking. Also air does not hold a whole lot of BTU's per cubic foot.

Hence the benefit of a front access for ease of entry and access to what you want offsets the small loss of cooling efficiency form having a front access. The biggest issue is to have good seals on the door surfaces.

All the issues Calder talks about insofar as insulation thickness, and gasketing and reduced conduction bode well for either ice boxes or mechanical refrigeration.

Refrigeration is incredibly expensive compared to ice and I would never consider mechanical refrigeration on a boat unless it was a liveaboard myself.

Link to comment
Share on other sites

Test box is progressing:

Inverted, with a chopped off syphon line and a new bottom drain:

IMG_2965.jpg

Syphon line will retain about 4 inches of meltwater. For testing, bottom drain can be corked, which is one normal way of sealing it off if you want to. Flaw with that is you have to did to the bottom of the box to pull the cork. Another way is to drill larger holes in the bottom, then glue several layers of backing plates to the bottom, creating a small drain well. Seal it off with a large, flat rubber bathtub type flopper stopper on a pull chain. That also seals it off and might eliminate the loop.

I have grave concerns over the bottom loop drain. That loop will always have water in it....winter layup included. Someday you would forget to drain it or dump antifreeze in it and it's going to freeze and bust and you can never get to it without tearing the whole thing out.

Next concern is the cold water loop is nearly 2 inches deep, looping it outside the 4 to 5 inches of insulation. Lastly, for gravity to work, you have to watch the drain level in relation to the waterline. I've heard some have to drain to a small electric bilge pump to eliminate the meltwater. The side drain offers elevation.....at least to the bottom of the box.

Interior of box, showing drains:

IMG_2968.jpg

Construction methods I've found include glassing entire interior, just the bottom, or just epoxy, with no glass at all. This one has xynole polyester on the bottom. The real deal should be completely lined and possibly 2 or 3 coats of white epoxy paint. Imagine dropping a 20 pound block of ice on this. Would it hold up? It might need a rubber mat in the bottom to cushion the bottom from the pounding a block of ice can give.

Exterior box is about ready:

IMG_2969.jpg

Sanity took over and I cut the bottom and sides to 2 feet square, resulting in insulation that is about 5 inches thick vs. the 6 I wanted. But that meant a lot of wasted plywood from odd shapes. This will suffice for a test. Top of the ice box and top rim of the exterior box will be level. Still need a lid design.

Link to comment
Share on other sites

Ray is correct on the side door, top door theory. For ice, I think you strictly go top lid access. The open topped freezers in the grocery store seem to work fine that way. Cold air isn't going to rise very far.

As for a top loader, yes, some stuff does pile up, but I'm not going to have 8 cubic feet of storage. One Cu. Ft. is about all I'm shooting for. I can dig through a foot of stuff. (Less being more).

Link to comment
Share on other sites

Pardey book (Care and Feeding) arrived yesterday. Crib notes version is:

#1 Top loading (ideal is large opening lid and smaller access lid)....double or triple gaskets to seal the lids.

Advocate a large box to fill available shape....so much for square. By large, I mean 100# or more of block ice. That gives them 2 weeks or so of cold storage. I'm hoping for the 2 weeks, but would like far less ice if that's possible.

Stainless steel liner is best, but if plywood is used, triple glass it. Concern is the weight of a dropped block of ice smashing into it. (This morning I found myself staring at a fiberglass laundry sink in my basement and started to imagine how that might be converted into the interior chest. It even has a drain already built in).

#2 Insulation is the BIG difference. They do not favor poured foam. Instead, they suggest multiple sandwiches of tin foil and 1/2" thick polyurethane board insulation...they max out at 4 inches. Sheet of foil (shiny side out) between each layer of foam.

Bottom drain with loop....drain the melt water....save that to cool your beverage. They use hose vs. something like my pvc. Say it's important to be able to disconnect it to clean it. Over time, the hose may fill up with bacteria and mold and can clog. Drain opening needs to have a screen to prevent food and other stuff from clogging the line. When the ice runs out, it's a good idea to clean the inside of the box (with bleach). It then makes a nice dry storage box that bugs, etc can't get into.

Things that I have been fretting over, like potential cold loss from a lid built of a hard, conductive material, they don't even mention. Lid idea is to have a tapered plug. Top will then be flush with the counter top.

Lots of other very good information about this and just about every other aspect of extended time spent on a boat. I find the contrast between Calder and the Pardey's to be remarkable. I know Calder has a well deserved reputation as an expert on all things mechanical on a boat. But mechanical also means something that can break down or fail. I clearly favor the simple, robust systems the Pardey's advocate.

******

I'm still going to try the two part foam insulation for this test box. I have it and want to try it. Also, I'm not sure I can find polyurethane board locally if I wanted to. Styrofoam, polystyrene, polyiso...something, with foil face. All these insulation boards are for the construction industry, but as near as I can tell are only intended for static insulation use. None of them are structural as in ability to support a load. I've got some pink board and am going to set sheet of it in the back of my pickup and put a weight on it and drive around with it back there for a while. All the bumps etc. are what I would expect an ice box to be subject to. Will then see if it holds up or crushes.

Link to comment
Share on other sites

Here's how an engineer would look at the cooler problem and tell you what you already know. There are three things going on of interest. (1) heat transfer through the wall of the box, (2) mass transfer ie air or water into or out of the box, and (3) heat transfer between items within the box.

(1) Heat transfer through the walls is just conduction. The most important variables will be the r-value of the insulation and something called the heat transfer coeffecient at the interior surface of the cooler wall. The coeffecient for water is much higher than air, which means the underwater portion of the cooler will transfer heat faster than the dry upper part.

(2) Mass transfer is pretty simple. Air leakage is obviously bad. Draining cold water looses the cooling capacity of the water and replaces it with warm air.

(3) heat transfer between items within the box is a bit of a red herring. Blocks of ice last the longest because they have smaller surface area then cubes. They both last longer when kept dry.

So using block ice and keeping it dry makes sense, but it comes down to a trade-off when you look at draining water. In an uninsulated box or perhaps even a poorly insulated cooler draining the water would improve performance becasue it dramatically slows down the heat transfer through the walls. In something supper insulated, the change in overall heat transfer associated with draining the water would be less, and might not be worth giving up the remaining cooling capacity of the liquid water.

Link to comment
Share on other sites

Lots of other very good information about this and just about every other aspect of extended time spent on a boat. I find the contrast between Calder and the Pardey's to be remarkable. I know Calder has a well deserved reputation as an expert on all things mechanical on a boat. But mechanical also means something that can break down or fail. I clearly favor the simple, robust systems the Pardey's advocate.

Larry Pardey also has a reputation too. He says not to use epoxy as heat will cause it to soften and the boat may fall apart.

Despite loads of survey proof and plenty of evidence that epoxy joined boats hold up fine.

Foil barriers (radiant Barriers) have a place, but for them to work you need air space between each foil If the foil barriers are in contact with the insulation on both sides, the benefit is largely lost.

Heat conduction is heat conduction. Doesn't really matter if the cooling method is mechanical or ice. Good insulation and design will minimize heat gain and reduce the work that either method needs to take care of. The very same things that will keep the amp hr demands down with mechanical refrigeration will also work to keep your ice lasting longer.

Heat goes from an area of greater concentration to one of lower.

It moves by conduction, convection and radiation.

Keep your icebox interior as small as you can get by with. Two different flanges on box access with gaskets on both and 6 inches of insulation all around.

There are high tech insulation chocie out there that involve foam packets in foil packets with a vacuum pulled on it that allows you the same insulation value with less thickness albeit at considerable cost.

For an icebox, the bigger the block of ice the less surface are to mass rtatio so longer use.

Drain off melt water to keep ice lasting longer.

In my mind having one drain trap to splash a cup of non tox in at end of season is no great problem. Loads of boats out there serviced every year that use a few gallons of non tox every year. 1 cup down the drain is tiny...

I never bother with a built in icebox myself.

I have a carry on 5 day cooler I fill with frozen food. I have another carry on cooler I transfer the next days food into each night. As that defrosts it keeps the food in there cold.

These two in combo will last me better part of a week with no need for ice.

I could easily extend with no ice simply by having non refrigerated food options for a bit. Or stop at a store and buy more food and a block of ice.

Ice is pretty cheap.

About a buck a day by and large in a descent carry on icebox.

In fact it is so cheap I can't imagine spending all that much money for the top of the line icebox myself.

But then again I sail in Maine. I guess if I was sailing where ambient temps are higher I might think differently.

Link to comment
Share on other sites

It makes absolutely no difference which way aluminum foil is oriented (shinny side out). More Pardey unresearched silliness.

An elementary science project for most 5th graders is to measure the temperature of a glass water, during the life span of the ice cube in it. To most folks surprise, the water remains at 32 degrees right up until the ice is gone. A grate will keep the ice dry and you'll save the cooling capacity of the water too, not to mention the internal volume it occupies.

If you want to get clever, you could drain off and pump the water through a coll surrounding the box.

Link to comment
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

Loading...


Supporting Members

Supporting Members can create Clubs, photo Galleries, don't see ads and make messing-about.com possible! Become a Supporting Member - only $12 for the next year. Pay by PayPal or credit card.




×
×
  • Create New...

Important Information

By using this site, you agree to our Terms of Use.