Is all ice the same?

[Goochi]

What will the best type of ice to cool fish I catch and place in my icebox. Frozen plastic bottles of freshwater or saltwater? - assuming that they both start at the same temperature coming out of my freezer. My gut feeling is saltwater but I cannot figure out why. Will the fact that they are both encased and cannot melt into free space make a significant impact on their ability to chill the fish?

[Todddo]

Fresh tap water - 1 tablespoon of salt per 1ltr of water

http://antoine.frostburg.edu/chem/senese/101/solutions/faq/why-salt-cools-icewater.shtml
Bit of info for you

Mythbusters did a thing ages ago on what ice is the coldest. I think the above formula is what they came up with :)

[NAGG]

Salt water freezes at a lower temp ....... so you have a colder starting point -
If I was going out for a feed - I would freeze up 2 x 5kg blocks of salt water (half a cup of salt to 10lts of water) & add it to approx 10lts chilled salt water ........ you can add sea water in place of the chilled salt water when out on the water - but it wont last as long.

Chris

Freeze the salt water blocks at as low a temp as you can over as long as you can (7 days)

[Freeeedom]

The best water to keep your fish in is the water you caught them in. If you throw crushed ice into this it will dilute the salt as it melts and this will result in your fish absorbing water through their gills. This could affect the quality of the fish. Using ice in containers so that it can cool your water but not mix with it is the better option by far. I have a block of ice in a plastic storage box which I put in my big cooler and then add a bucket of the water I'm fishing in. The water is chilled by the melting ice and the fish go straight into that. When I get home the plastic box (half melted) goes back in the freezer to freezee again for the next trip.
Adding salt to melting ice causes a reaction which lowers the temperature below freezing. It is possible ( but not practical) to get a temperature as low as -20 degrees celsius by doing this. (This property was used to make ice cream before the invention of refrigerators).
This does not help us with cooling fish however. If you make your own ice with salt in it and freeze it at home it will freeze at a lower temperature (if your freezer is good enough!), but it will come out of the freezer at the same temperature as ordinary ice - that is the temperature of your freezer. When it melts it will melt at a lower temperature than ordinary ice - therefore it will melt a bit sooner than ordinary ice as it takes heat from its surroundings.
But the main thing is that the cooling effect of ice comes from the fact that it takes a lot of heat to turn ice into water - this heat is called the latent heat of fusion - and for pure water it has a value of 80 calories per gram of water. This means that to turn 1 gram of ice at zero degrees into 1 gram of water at zero degrees requires 80 calories (or 332 joules) of heat. This is the same amount of heat that would be needed to heat 1 gram of water at zero degrees to a temperature of 80 degrees - so you can see that there's quite a lot of heat needed to melt the ice and that heat comes from the surroundings - meaning your fish.
Adding salt (or any other substance) to water lowers its freezing and melting point but does not alter the latent heat of fusion.
Sorry if this got a bit technical. Hope it helps!
Cheers Freeeedom

[FisHard]

I feel so dumb :(

[Todddo]

I feel so dumb :(

Google makes me look smart B)

[fishfeeder]

Is a few degrees really going to make any difference to the eating quality of the fish..... ???
I would be more inclined to look more into cooking method to get the best out your catch then the temperature of the ice...

Most people fish for a day maybe 2.. So as long as the fish is killed and bleed and put in a ice slurry say a 60L esky with 2 bags of ice with about 5L of salt water in a quality esky, its going to stay cold all day and when you get home there will be still heaps of ice in the slurry....

The only problem I find is getting the fish to go into the esky !!!

[nathank]

A few degrees will make no difference whatsoever.... an ice slurry in a good esky will keep the fish perfect till you get them back for cleaning.. its what ya do with them after that ..that will determine how they taste ;)

[softplasticsdude79]

try packing 2 x 2litre coke bottles full of newspaper and 1 tablespoon of salt.a bit of food colouring for visuals if you like.i take 2 of these in my 70 litre esky and it does the trick.

i packed 1 1/2 sundays mails per bottle.

i have used these for 2 days at a time,brought them home and there still rock solid except for 2 cms around out edge,good cheap ice bricks,that stay frozen 4 times longer than any ice bricks i have brought before.

[cuzzamundi]

Softplasticsdude,

Mate, you've sold me. One (stupid) question: is it just the paper and salt-no water at all? Sounds like a ripper idea.

Cuzza

[softplasticsdude79]

hi Cuzza,

you need to fill with water,but shred the paper and fill with as much paper as you can,trust me,it will take an hour per bottle,or in my case a 1 hour massage on my missus for 2 bottles done,she used a wooden spoon handle upside down to jam inside and keep compressing the paper,and a little water every now and then until full of paper and water and packed solid,it will then take 2 days to freeze solid.i got the idea from mythbusters when they built a paper mache boat,put a yamaha 4 stroke 100hp (or something similar) on the back and drove it for 20 minutes before it started to break up,they proved that paper and water together is much stronger than just water.

[Triple]

Just try to freeze your salt/fresh coke bottles/ice cream tubs/paper mache mixed containers for as long as possible before use. Deep frozen ice seems to last at lot longer than water that has only been frozen for a day or two. (We use 4L ice cream containers that sit in the freezer all the time and rotated - frozen for a few weeks before use) I thought frozen was frozen but results show different..
Also using previously boiled water seems to last longer too.. something about no air to break down the ice quicker?

[odes20]

Facinating stuff!

Gonna try it, including ther massage, dont know if I could last an hour tho.


hi Cuzza,


you need to fill with water,but shred the paper and fill with as much paper as you can,trust me,it will take an hour per bottle,or in my case a 1 hour massage on my missus for 2 bottles done,she used a wooden spoon handle upside down to jam inside and keep compressing the paper,and a little water every now and then until full of paper and water and packed solid,it will then take 2 days to freeze solid.i got the idea from mythbusters when they built a paper mache boat,put a yamaha 4 stroke 100hp (or something similar) on the back and drove it for 20 minutes before it started to break up,they proved that paper and water together is much stronger than just water.

[Goochi]

Thanks everyone, especially Freeeedom. So unless a chemical physicist comes along and tells us otherwise there is no difference as the latent heat of fusion is the same for both salt and fresh water. Both types of ice will melt at different temperatures but will still absorb equivalent amounts of heat. I know that making an ice slurry will chill your catch faster but in my case I don't do it for two reasons. One - here in the tropics the surface ocean temp is aroud 30 deg C and I don't want to waste my ice chilling the hot water. Two- I fish on a budget and have a hand me down fibreglass icebox(that I have refurbished); I don't want a lot of liquid in it because it will eventually find it's way into the insulation an wreck the box(hence the plastic bottles). Also I don't use a 60l icebox 'cause it's too SMALL.

[Freeeedom]

Half your luck Goochi - I wish my 60 litre ice box was too small for what I usually catch!
Just a point about filling your Coke bottles with paper first. Because you are replacing some of the volume with paper (which does not melt) instead of water/ice (which does melt) you are actually reducing the amount of cooling that the frozen bottle can produce, since it's the melting of the ice that does most of the cooling. If you want to use Coke bottles I would use just water, but squeeze the bottle a bit before you screw the cap on so that as the water freezes and expands it doesn't blow the bottle apart.
Cheers Freeeedom

[softplasticsdude79]

Half your luck Goochi - I wish my 60 litre ice box was too small for what I usually catch!
Just a point about filling your Coke bottles with paper first. Because you are replacing some of the volume with paper (which does not melt) instead of water/ice (which does melt) you are actually reducing the amount of cooling that the frozen bottle can produce, since it's the melting of the ice that does most of the cooling. If you want to use Coke bottles I would use just water, but squeeze the bottle a bit before you screw the cap on so that as the water freezes and expands it doesn't blow the bottle apart.
Cheers Freeeedom

i tried just using water and they melt far quicker than the paper filled bottle,sure,the paper filled bottle may not have the cooling power of just melting water,but,as far as keeping your esky and goods inside very cold for a longer period of time than just water blocks,the paper/water combo works just fine for me,and have not had a bottle expansion issue in 100 uses/freezes.

http://www.youtube.com/watch?v=iHufDv6obrU&feature=related

[Triple]

Also try to cool down the eski the night before use.. Put some sacrificial ice/bottle or 2 in the night before and put you fresh stuff in when you leave. AND keep it in the shade and don't open it unless you need to.

[Goochi]

I have been thinking about the paper mache ice in the coke bottle. I suggest this type lasts a long time because it is partially insulated by the paper. If this is the case then it will actually inhibit the cooling effect imparted to the contents of the icebox. The ice will be preserved because it has not been able to soak up the heat from its surroundings. Do any of you great people have a thermometer to do this experiment to test my theory. Make two bottles of ice, one plain the other paper mache type; freeze them both for a couple of days. Get two identical buckets with the same volume of tap water in them and place one ice bottle in each bucket. Measure the temp of the water in each bucket every 5mins for half an hour or more. I think the plan ice will chill the water faster.

[Triple]

http://hyperphysics.phy-astr.gsu.edu/hbase/thermo/firlaw.html#c1

[fishfeeder]

Might chill it faster but by the sounds of it the paper added bottle will keep the water cold for longer... would be interesting to see the difference.
One other thing you can do to keep the ice longer is to place a wet towel/Hessian Bags over the ice/fish in your fish box.. This will help keep the temperatures down...

[nathank]

Man the paper/ice idea is a cool one... im deffo gunna try it....

[Lucky Loz]

My brother used to use 2 litre milk bottles of frozen fresh water. They would keep the water cool but not cold and you could then drink them as they melted. But not cold enough for a nice cold beer. The plastic itself insulates and more so is a layer of air that forms between the ice and the bottle. Not much chop in my opinion. A couple of home made block ice in "camping wash tub" size, frozen for a good weekor more. . And a bag of party ice. Then a bucket or two of sea water. Party ice melts and brings temperature down quickly and blocks last for ages. 8-)

[softplasticsdude79]

I have been thinking about the paper mache ice in the coke bottle. I suggest this type lasts a long time because it is partially insulated by the paper. If this is the case then it will actually inhibit the cooling effect imparted to the contents of the icebox. The ice will be preserved because it has not been able to soak up the heat from its surroundings. Do any of you great people have a thermometer to do this experiment to test my theory. Make two bottles of ice, one plain the other paper mache type; freeze them both for a couple of days. Get two identical buckets with the same volume of tap water in them and place one ice bottle in each bucket. Measure the temp of the water in each bucket every 5mins for half an hour or more. I think the plan ice will chill the water faster.

goochi,

i reckon a plain bottle would chill the water faster,but im more interested in my esky staying cooler for longer,not how fast it cools,I usually pour in 4 litres or so of water as soon as i arrive,generally 30 mins later its cold and within an hour its to the point where its chilled and ready for my flatty,I reguarly throw in 5 flathead into my esky and this method has kept them icy cold before for over 24 hours at times,i have even left these in an empty esky at times for 2-3 days and still find they are half frozen,Whilst not the most efficient chiller as far as chilling times goes or making the goods inside ice frozen cold,what it does do,is outlast all other icebricks by a country mile,and best of all is free to use and make.and although they cant compare to bagged ice I havnt brought bagged ice for a long time.

i will do the experiment on saturday and post up the results.

[PinHead]

Half your luck Goochi - I wish my 60 litre ice box was too small for what I usually catch!
Just a point about filling your Coke bottles with paper first. Because you are replacing some of the volume with paper (which does not melt) instead of water/ice (which does melt) you are actually reducing the amount of cooling that the frozen bottle can produce, since it's the melting of the ice that does most of the cooling. If you want to use Coke bottles I would use just water, but squeeze the bottle a bit before you screw the cap on so that as the water freezes and expands it doesn't blow the bottle apart.
Cheers Freeeedom

to work this out you would need the specific heat of both the bottle..the water and the paper to acquire the heat absorption of them combined.
Also..the size of the bottle makes a difference as the heat is absorbed into the ice based on the available surface area .

[PinHead]

but..if it keeps ya fish at the temp you want it then all is good.

[Freeeedom]

to work this out you would need the specific heat of both the bottle..the water and the paper to acquire the heat absorption of them combined.
Also..the size of the bottle makes a difference as the heat is absorbed into the ice based on the available surface area .

Not quite Pinhead. The specific heat is the heat needed to change the temperature of the material without it changing state (solid to liquid etc). The calorie is defined as the amount of heat needed to raise the temperature of 1 gram of water by 1 degree centigrade. This means that the specific heat of water is 1. This is (possibly one of) the highest specific heats of any substance.
The latent heat of fusion (melting) is the heat needed to melt one gram of water at zero degrees to one gram of water still at zero degrees. The value is 80 calories per gram for water.
This means that in this discussion it is the melting of the ice that is the key absorber of heat.
Here's an example to show the difference.
Lets say you have a 2 litre coke bottle of water that comes out of your freezer at minus 10 degrees centigrade - that's colder than most household freezer's I think. It will absorb 2000 (the number of grams) times 10 (the temperature change) times 1 (the specific heat) or 20000 calories as it warms up from minus ten to zero degrees.
It will then start to melt at zero degrees and will absorb 2000 (the number of grams) times 80 (the latent heat) calories or 160000 calories as it melts. That's 8 times the heat absorbed with no change in temperature.
So the key is the melting of the ice - the more ice you've got the better it will work.
Fishfeeder has a very good point. If you can limit the amount of heat that gets into your esky your ice will last a lot longer. The easiest way to do this is to cover the esky with a wet towel and keep it out of the sun. This is very effective, especially in summer when the temperature difference between the inside and outside of the esky is large - this makes the heat travel through the esky more quickly.
Cheers Freeeedom
(Sorry for the late reply - I've been away for a week - catching very little!)

[Cav(J.C.)]

Try the Technice flexible ice pads.Wrap around anything--I use them in eskys, byo bags, champagne buckets, and dispursed between fish and ice.
Follow the destructions, and you can't go wrong.
Cav(J.C.)