Biggest at CostCo I can currently see is only 85 litres for £100


That's a really interesting point:Insulation [...] will only work against you for fresh, still-warm carcasses
The blocks are probably filled with water with a small percentage of salt. Some interesting videos on YouTube about it.I have a 56 Litre IceyTek coolbox that I bought for spearfishing, it will take a Roe or a muntjac or two.
They do them up to 1100 litres, and they are beyond excellent, not cheap though.
The Iceytek ice blocks are worth considering - they seem to freeze colder than normal ice blocks and hold the temperature better - I assume they have some clever chemical compound in them. You do have to watch out for them freezing stuff they come into contact with - I laid a decent seabass directly onto one once and it properly froze the side in contact.
Icey-Tek Cool Boxes
This is what I use. Skin and quarter the deer, pack with plenty of ice blocks. Used to bring reds back from Scotland this way, 12 hour drive, no issue wifh venisonColeman do oversize 100lt coolboxes which are solid, wheeled easy to clean and cheaper than the igloos
here
Yeah.The blocks are probably filled with water with a small percentage of salt. Some interesting videos on YouTube about it.
I have lots of gel blocks.Yeah.
I assume that even cheap blocks have salt in them, a quick google suggests that more expensive gel blocks contain propylene glycol to bring the freezing temperature right down.
Either way they work like a charm