Bottleinamessage, This is not to get on your case, so please don't take it that way. I did a small amount of research to see what the Viking people had to say about their rafts and they made no mention that I could find of vacuum packing. So I guess my first question: is vacuum packing more like ground coffee in a can or more like vacuum sealing, like coffee beans in a bag? One would think it would be like beans in a bag if it were a soft valise.
Here's the link to their brochure:
RescYou™ liferafts
However, I do not understand the value in having a liferaft vacuum packed. Here are my issues/questions:
1) Coated fabrics tend to pin hole when folded then folded again. Such folds put alot of stress on the coating and fabric on the outside of the final fold. The idea of compressing that fold even harder as is the case of vacuum packing would perhaps tend to exacerbate the problem of pin holing.
2) Because of the harder compression the plasticized material would perhaps be more prone to sticking/welding/glueing together. And should one need to do the rapid inflate (pop the raft) where the fabric is near frozen in the areas near the valve (due to expansion of CO2) would this cause more possibility of these stuck together coatings separating from the fabric?
3) And in conjunction with the above, the relative flexibility of many coatings is due to plasticizers in the plastic. As they evaporate out coatings get brittle. Usually lower atmospheric pressures cause lower evaporative temperatures (for instance, water boils at a lower temp at altitude etc.) So does placing the plasticized fabric under a vacuum cause the plasticizers to more rapidly come out of the coating? Perhaps gluing the layers together? Or do the coatings tend to dry out and become more brittle sooner?
These are just some questions that popped into my head when you mentioned vacuum packed liferafts. Personally I think carefully packed in a dry nitrogen atmosphere might be better than vacuum packed.
Bests,
Wiley