The biggest problem is cold shock which increases the chance of drowning and generally its the drowning that gets you before the hypothermia. Definitely a good life jacket with a hood and designed such that it won't ride up in the water. I spend my working life over the water and don't venture out without a survival suit. Life raft would be good if it's tied down so that it won't kill you on impact, you manage to get it out once you are in the drink, it inflates and doesn't blow away and can finally manage to get in it. I think just having one without proper training offers a false sense of security.