Efficient Cool Box

[Sea Dog]

Is there such a thing? I know a compressor fridge is far more efficient and these are often only meant to keep stuff cool on car journeys so can eat juice continuously, but a friend with an outboard powered cruiser and a small solar array needs something to store essential medication for the odd night or three... and a bottle of milk wouldn't go amiss!

 

Anyone have a solution that works in a similar situation?

[mrsmelly]

9 minutes ago, Sea Dog said:

Is there such a thing? I know a compressor fridge is far more efficient and these are often only meant to keep stuff cool on car journeys so can eat juice continuously, but a friend with an outboard powered cruiser and a small solar array needs something to store essential medication for the odd night or three... and a bottle of milk wouldn't go amiss!

 

Anyone have a solution that works in a similar situation?

A few companies make compressor cool boxes to include Dometic for around 400 ish notes.

[CompairHolman]

Cool boxes work on thermoelectric cooling principle and it requires a lot more energy than a compressor fridge, its beyond science at the moment to make a low power drain cool box. 

[WotEver]

To the best of my knowledge the only options are Absorption (inefficient), Peltier (highly inefficient), Compressor (efficient but expensive and bulky), or evaporative using a water spray. I don’t believe that the latter will drop the temperature by much though. 

[Alan de Enfield]

17 minutes ago, Sea Dog said:

Is there such a thing? I know a compressor fridge is far more efficient and these are often only meant to keep stuff cool on car journeys so can eat juice continuously, but a friend with an outboard powered cruiser and a small solar array needs something to store essential medication for the odd night or three... and a bottle of milk wouldn't go amiss!

 

Anyone have a solution that works in a similar situation?

Many years ago we had one of these.

It is a steel box with a door, it is surrounded by Plaster of Paris, and has a depression in the top.

You fill the depression with water and it trickles down all the holes in the plaster, keep filling it until it stops disappearing.

 

As the water evaporates it cools the contents.

Certainly worked keeping our milk and 'stuff' cool.

 

There are several makes - one is the "Osokool"

 

 

 

 

 

 

You can also make a DIY version using two clay flower pots (without holes in the bottom)

One big one and one 2 or 3 inches smaller - put the small one inside the big one

Fill the gaps around it with sand (or something like crystal cat litter)

Fill with water, cover top with a wet towel

Keep damp.

 

 

 

Edited August 26, 2019 by Alan de Enfield

[Sea Dog]

10 minutes ago, mrsmelly said:

A few companies make compressor cool boxes to include Dometic for around 400 ish notes.

Eek!

9 minutes ago, CompairHolman said:

Cool boxes work on thermoelectric cooling principle and it requires a lot more energy than a compressor fridge, its beyond science at the moment to make a low power drain cool box. 

That's pretty much what I thought.

9 minutes ago, WotEver said:

To the best of my knowledge the only options are Absorption (inefficient), Peltier (highly inefficient), Compressor (efficient but expensive and bulky), or evaporative using a water spray. I don’t believe that the latter will drop the temperature by much though. 

Which sort of confirms the above.

8 minutes ago, Alan de Enfield said:

Many years ago we had one of these.

It is a steel box with a door, it is surrounded by Plaster of Paris, and has a depression in the top.

You fill the depression with water and it trickles down all the holes in the plaster, keep filling it until it stops disappearing.

 

As the water evaporates it cools the contents.

Certainly worked keeping our milk and 'stuff' cool.

 

There are several makes one is the "Osokool"

 

Ah! Similar to the wet terracotta principle. Worked well for donkey"s years for dairy and the like, but I'm dubious about it meeting the medical requirement. I'll point her at "Osokol" though - it might just help enough.

 

Thank you chaps!

 

Anyone have a best practice suggestion from small cruiser experience?

Edited August 26, 2019 by Sea Dog

[Alan de Enfield]

9 minutes ago, Sea Dog said:

Anyone have a best practice suggestion from small cruiser experience?

Keep the battery charged and buy a fridge ?

 

 

@Sea Dog

 

More seriously (but at a cost) I have seen these successfully used;

 

They 'flip' over :

You can drop it down when cruising and it becomes a water driven generator powered by the forward movement of the boat.

When you moor up it can be turned around and used as a wind driven generator.

 

Certainly puts the amps back into a battery and, can, work 24 hours per day.

 

https://eclectic-energy.co.uk/products/duogen/

 

Water mode performance

• 5amps at 6 knots (100W) 190 Ah per day
• 8 amps at 7 knots (150W) 275 Ah per day
• 16 amps at 8 knots (200W) 380 Ah per day
• Minimal loss of boat speed
• Easy to deploy and recover
• Proven in all sea states
• Can provide all the power for a yacht on passage

Wind mode performance

• 5 amps at 10 knots wind speed (30W)
• 6 amps at 15 knots wind speed (75W)
• 11 amps at 20 knots wind speed (140W)

Edited August 26, 2019 by Alan de Enfield

[Sea Dog]

Just now, Alan de Enfield said:

Keep the battery charged and buy a fridge ?

Yes! By Jove, I think you have it! Add a paddle wheel and we have the complete package! 

[Chewbacka]

If it is only for a day or two and not very often you could get a small well insulated cool box - not powered - and buy a 2kg bag of ice from the supermarket.  One bag would probably last a couple of days if you minimise open the lid.

 

a couple of 2kg ice is about a quid 

 

concerns - if it is more than a couple of days you will need more ice or your medicine may get too warm.  Also you may also cool the medicine too much, so if liquid a risk of freezing.

Edited August 26, 2019 by Chewbacka

[Sea Dog]

1 minute ago, Chewbacka said:

If it is only for a day or two and not very often you could get a small well insulated cool box - not powered - and buy a 2kg bag of ice from the supermarket.  One bag would probably last a couple of days if you minimise open the lid.

Yes indeed, and thanks. I think she already does this for short breaks, but is really looking for something a bit less restrictive. I knew it was a tough ask... as soon as she asked me! 

[Jen-in-Wellies]

The terracotta evaporation fridges have intrigued me for a while and I may make one to play with. I suspect it would work better in some combinations of ambient temperature and relative humidity than in others. It would be worthwhile for anything that she tries to experiment with it before going away, using a fridge thermometer to show the internal chamber temperature, so she can be sure it will keep her medication within range.

 

Jen

[system 4-50]

Linked to an ecofan stuck to the inside of the roof steel to provide a draft?

[CompairHolman]

The standard boat fridge is constantly battling against the poor level of insulation in the cabinet which is made to fit in a small space rather than minimal power use,  and with being in a bigger insulated box ( your cabin ) that you are also trying to heat at the same time as trying to cool the fridge. Once vacuum panel insulation becomes affordable ( 20 times more efficient than PU foam , 38 times Rock wool ) then there could be a properly insulated fridge come on the market which would not require 120+ mm of foam to achieve maximum insulation.

 

Its probably affordable now if you factor in the long term cost of generating the power to run a standard badly insulated fridge. Probably around £100 extra cost for the average boat fridge. 

[Murflynn]

1 hour ago, CompairHolman said:

The standard boat fridge is constantly battling against the poor level of insulation in the cabinet which is made to fit in a small space rather than minimal power use,  and with being in a bigger insulated box ( your cabin ) that you are also trying to heat at the same time as trying to cool the fridge. Once vacuum panel insulation becomes affordable ( 20 times more efficient than PU foam , 38 times Rock wool ) then there could be a properly insulated fridge come on the market which would not require 120+ mm of foam to achieve maximum insulation.

 

Its probably affordable now if you factor in the long term cost of generating the power to run a standard badly insulated fridge. Probably around £100 extra cost for the average boat fridge. 

There may be a magic insulation material that is 20 times more efficient than PU foam, but the law of diminishing returns applies.   There comes a point where it is far more important to analyse where and when heat can creep in - think seals, opening the box, and so on.

[CompairHolman]

2 hours ago, Murflynn said:

There may be a magic insulation material that is 20 times more efficient than PU foam, but the law of diminishing returns applies.   There comes a point where it is far more important to analyse where and when heat can creep in - think seals, opening the box, and so on.

Yes this law applies but only when you reach the point of maximum practical insulation, with PU foam as you go thicker the gain in insulation decreases , at around 120 /150 mm it becomes too much wasted space for the small gain in insulation, vacuum panels don't need to be massively thick to achieve the same insulation values.

 

 Any fridge design with high efficiency in mind would be top opening.  

 

[David Mack]

8 hours ago, Alan de Enfield said:

Many years ago we had one of these.

It is a steel box with a door, it is surrounded by Plaster of Paris, and has a depression in the top.

You fill the depression with water and it trickles down all the holes in the plaster, keep filling it until it stops disappearing.

 

As the water evaporates it cools the contents.

Certainly worked keeping our milk and 'stuff' cool.

 

There are several makes - one is the "Osokool"

 

 

 

 

 

 

Would only cost you £9.10 for the double size model!

[Sea Dog]

So, has no-one with a ubiquitous canal "yoghurt pot" anything to offer on this? Surely someone with outboard power uses and stores dairy or keeps medicine cool in such a craft?

[Alan de Enfield]

19 minutes ago, Sea Dog said:

So, has no-one with a ubiquitous canal "yoghurt pot" anything to offer on this? Surely someone with outboard power uses and stores dairy or keeps medicine cool in such a craft?

I've already shown what we had when 'outboarding'.

[rusty69]

We use a big icey tek coolboox in the winter as our main fridge. Ice packs from the freezer keep it cold for days. I spose cheap supermarket ice would have the same effect. 

[Tumshie]

1 hour ago, Sea Dog said:

So, has no-one with a ubiquitous canal "yoghurt pot" anything to offer on this? Surely someone with outboard power uses and stores dairy or keeps medicine cool in such a craft?

Cool boxes are a god send for storage but I never dip in and out of one, you can buy big bags of ice from any supermarkets BUT the bags are thin and the ice is jabby so when it melts the you get a big puddle at the bottom of the box; never once have I not had this happen. A really good quality (unpowered) cool box if packed and used efficiently can keep things cool for quite along time (days in some cases) but how long depends on how well you've packed it, where you've stored it and how hot it is where you've stored. The trick is to get one as big as you can store and fill it with as much frozen stuff as you can, even if that means freezing stuff you you wouldn't other wise bother to; the big thing to remember is it os not a fridge don't store your open milk in there and then dip in and out of it and don't leave the lid open for any longer than than you absolutely must if at all possible. 

 

https://www.gaelforcemarine.co.uk/en/Waeco-Passive-Cool-Ice-Box/m-3909.aspx

 

Over the years I've used lots of different brands of UHT milk and they are all horrible tasting but you just had to suffer it or have no tea, when I found out I was lactose intolerant I switched to Lactofree milk and their own UHT milk as well and I can hardly taste the difference, you can a bit but it is by far the UHT that tastes least like UHT. I buy it by the litre and in small single cup portion sizes. I have a stainless steel thermal bottle which goes in the cool box until I open the milk and then once the milk is decanted into that I don't have to keep opening the cool box. I strongly recommend having some sort of bungee to keep the lid secure preferably two to keep the box on an even keel.

 

https://www.tesco.com/groceries/en-GB/products/267309503

 

https://groceries.asda.com/product/lactose-free-milk/arla-lactofree-long-life-semi-skimmed-milk/44054

 

For meals I cook easy one pot type things, I split them up into single portion sizes in silicon freezer bags, I freeze them and then they can be packed frozen into a cool box. The silicon food storage bags are air and water tight and can go straight from freezer to boiling pan of water so you can cook your food boil in the bag style. I love these bags but you do get the odd one now and again that isn't as airtight as they should be. They are also the bee's knees for storing and freezing milk and or juice. Before the dawn of the funky silicone bags thing got vacuum packed. You can take food out to defrost but always make sure it is thoroughly cooked. 

 

https://www.amazon.co.uk/Reusable-Leakproof-Dishwasher-Microwave-Freshness/dp/B07S9Z2BJX/ref=sr_1_11?

 

 

For the medication I strongly recommend that you get a small air and water tight container to store it in regardless of how you chose to store it. The medication stored safely in its own container can then be kept in the cool box but I would stick a thermometer in the bilge and see if it is cold enough down there. But as you're on a boat there is always the wet towel option - make sure medication is in a watertight container and dip a small towel or a couple of facecloths in the water and wrap medication in the cloths. you can do the same with a thermos of milk. If you don't want the cloth wrapped around the meds get an old Tupperware container and remove the lid and wrap that instead. 

 

 

Edited August 27, 2019 by Tumshie
to add a link

[Sea Dog]

2 hours ago, Alan de Enfield said:

I've already shown what we had when 'outboarding'.

I know Alan - thanks and duly noted.

 

1 hour ago, rusty69 said:

We use a big icey tek coolboox in the winter as our main fridge. Ice packs from the freezer keep it cold for days. I spose cheap supermarket ice would have the same effect. 

Thanks also Rusty. I think they've already got the standard cool box weighed off, but are seeking low-powered options to extend their range.

1 hour ago, Tumshie said:

Cool boxes are a god send for storage but I never dip in and out of one, you can buy big bags of ice from any supermarkets BUT the bags are thin and the ice is jabby so when it melts the you get a big puddle at the bottom of the box; never once have I not had this happen. A really good quality (unpowered) cool box if packed and used efficiently can keep things cool for quite along time (days in some cases) but how long depends on how well you've packed it, where you've stored it and how hot it is where you've stored. The trick is to get one as big as you can store and fill it with as much frozen stuff as you can, even if that means freezing stuff you you wouldn't other wise bother to; the big thing to remember is it os not a fridge don't store your open milk in there and then dip in and out of it and don't leave the lid open for any longer than than you absolutely must if at all possible. 

 

https://www.gaelforcemarine.co.uk/en/Waeco-Passive-Cool-Ice-Box/m-3909.aspx

 

Over the years I've used lots of different brands of UHT milk and they are all horrible tasting but you just had to suffer it or have no tea, when I found out I was lactose intolerant I switched to Lactofree milk and their own UHT milk as well and I can hardly taste the difference, you can a bit but it is by far the UHT that tastes least like UHT. I buy it by the litre and in small single cup portion sizes. I have a stainless steel thermal bottle which goes in the cool box until I open the milk and then once the milk is decanted into that I don't have to keep opening the cool box. I strongly recommend having some sort of bungee to keep the lid secure preferably two to keep the box on an even keel.

 

https://www.tesco.com/groceries/en-GB/products/267309503

 

https://groceries.asda.com/product/lactose-free-milk/arla-lactofree-long-life-semi-skimmed-milk/44054

 

For meals I cook easy one pot type things, I split them up into single portion sizes in silicon freezer bags, I freeze them and then they can be packed frozen into a cool box. The silicon food storage bags are air and water tight and can go straight from freezer to boiling pan of water so you can cook your food boil in the bag style. I love these bags but you do get the odd one now and again that isn't as airtight as they should be. They are also the bee's knees for storing and freezing milk and or juice. Before the dawn of the funky silicone bags thing got vacuum packed. You can take food out to defrost but always make sure it is thoroughly cooked. 

 

https://www.amazon.co.uk/Reusable-Leakproof-Dishwasher-Microwave-Freshness/dp/B07S9Z2BJX/ref=sr_1_11?

 

 

For the medication I strongly recommend that you get a small air and water tight container to store it in regardless of how you chose to store it. The medication stored safely in its own container can then be kept in the cool box but I would stick a thermometer in the bilge and see if it is cold enough down there. But as you're on a boat there is always the wet towel option - make sure medication is in a watertight container and dip a small towel or a couple of facecloths in the water and wrap medication in the cloths. you can do the same with a thermos of milk. If you don't want the cloth wrapped around the meds get an old Tupperware container and remove the lid and wrap that instead. 

 

 

Thanks for taking the time to write all that very useful advice @Tumshie, which will also be of help to others viewing this thread in future. 

 

My involvement here is that I've been asked by a friend to recommend a powered coolbox that won't goose their batteries in double quick time on an outboard-powered grip cruiser. It's a tall order, I know!  In fact, the question commenced: "I know you said that powered coolboxes take too much power for our boat, but...."!

 

So, I'm alright Jack, I have a narrowboat with a Shoreline fridge, but what about the grp cruiser owners, eh?

 

[rusty69]

14 minutes ago, Sea Dog said:

Thanks also Rusty. I think they've already got the standard cool box weighed off, but are seeking low-powered options to extend their range.

Fairy nuff. Though I would say the icey tek is probably not a standard cool box.,it is pretty well insulated. It is very low powered too?

[Sea Dog]

33 minutes ago, rusty69 said:

Fairy nuff. Though I would say the icey tek is probably not a standard cool box.,it is pretty well insulated. It is very low powered too?

Ooh, hang on there Rusty, that bears a little more looking at, doesn't it. I'll give it a mention - it may well be a serious contender as a no-power alternative to the low-power solution they're looking for. Thanks again!

 

[rusty69]

8 minutes ago, Sea Dog said:

Ooh, hang on there Rusty, that bears a little more looking at, doesn't it. I'll give it a mention - it may well be a serious contender as a no-power alternative to the low-power solution they're looking for. Thanks again!

 

I think my mate Tumshie said something similar

"A really good quality (unpowered) cool box if packed and used efficiently can keep things cool for quite along time (days in some cases) " 

 

Yeti also make decent ones, though not cheap. 

 

Got ours from here fwiw

 

https://www.coolboxesuk.com/#header-nav

 

Edited August 27, 2019 by rusty69

[Tumshie]

1 hour ago, Sea Dog said:

My involvement here is that I've been asked by a friend to recommend a powered coolbox that won't goose their batteries in double quick time on an outboard-powered grip cruiser.

You said your friends needed something for the odd night or three and cool boxes like Rusty's Icey Tek and the Waeco Cool Ice Box are used by a lot of lumpy water sailors, they are not to be muddled with that blue Colemans crap that folk use to get their weekly shopping home, these types of boxes will keep things frozen for 3 days even in warmer weather. You asked what plastic boat sailors use well this is it. If your friend needs something then these are well worth looking into but they are not cheap. If they are on a canal and can get to the shops to buy more bags of ice these boxes will go on indefinitely.

 

Edited August 27, 2019 by Tumshie
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