Teefor Gage,
I can't believe your post, but if you have no experience offshore, then I do, however if you do have experience you should be concerned at your lack of awareness of what goes on around the helideck.
The net does contain the foam, should you ever watch a fuel fire demonstration on a deck with and without a net you will find that out!
As for nets, their prime function is to contain the helicopter, pilots and passengers are secondary. If you walk on them using a ladder principle then you will have no problem. Walk diagonally and it's difficult. As for tension, that is more difficult, wet or dry the tension is different, hense loose or not so loose. Very few decks use the rubber tensioners which if used correctly mean tight or tighter nets.
I have experienced an inadverdant brake release on a deck without a net, the main clue was the helideck crew making a rapid exit from the helideck. Also there have been cases reported of at least two helicopters moving on guano contaminated decks without nets. Both examples would have been contained if nets were fitted.
Amongst the other posts there are other misconceptions etc. although there are one or two out there who are on the same wavelength as myself.
Pprune or is it just prune?