I just signed up for a Winter Emergency Medical Course for the last week of February in NH. My sleeping bag is rated for 15* F, and I'll bet the weather will be colder than that. What options do I have so that I don't have to buy another sleeping bag?

Here is an option: Sea to Summit Reactor

However, you may want more warmth than this will provide. If your going to be living out of your backpack, I'd search for a deal on a new -15 degree bag (from a good manufacturer). I have had good luck with north face (but add 5-10 degrees to there rating) mountain hardware (rating is right on!) and REI (warmer than rated by 5 degrees or so). Before I invested in my mountain hardware system, I had a 15 degree bag and a 32 degree bag that fit over my 15 degree... that coupled with a goot pad and a bivy sack kept me warm to -20 in the open and -45 in snow. It was a good system that gave me options for all conditions I encountered.

I have one of these for emergencies, and lent it to a member of my rescue squad durning a drill. She had a cheaper 30 degree bag that wasn't cutting it for the 25 degree temp, we placed the Thermo-Lite bivy over her bag and she was comfortable for the night.

I agree with Romania's suggestions of a sleeping pad and the Thermo-Lite bivy sack. I have used a Thermarest pad for over ten years. It has kept me warm and comfortable on some rough and cold ground. I haven't used the bivy sack as an overbag, but the theory speaks fot itself.

If you want to avoid the expense of buying a new bag, you could add a fleece liner to your existing bag. Wearing polypro or wool long underwear inside the bag will also help. Finally, try wearing a fleece or wool hat when you sleep. My wife does this and swears by it.

Good luck,

Steve

"Finally, try wearing a fleece or wool hat when you sleep. My wife does this and swears by it."

Indeedy. For $5, it's hard to beat the wool watch cap available at nearly any surplus store.

A good thermarest pad, like a Prolite 4 is going to help a lot for starters. As for the bag, if you want to keep your existing 15 degree bag, you could add an overbag to stay comfortable at far lower temps. The FTRSS (Flexible Temperature Range Sleeping System) overbag that Wiggy's sells as part of the military 3-in-1 system is large enough to contain a normal mummy style bag without compressing the insulation. They are very durable, can get wet and still insulate, etc.

(Wiggy's makes a -60 degree bag!)
http://wiggys.com/category.cfm?Category=6

You might look into renting a warmer bag for the course. If you are not living out of a pack or traveling long distances you may look at using two lighter bags and a couple of foam pads under you.

I recomend a balaclava rather than a toque for sleeping at night as a toque will work its way off your head as you sleep. I also put boiling water in a water bottle, wrap it in some clothes and stuff it in the bottom of the bag to keep my toes warm but make sure that the lid is on tight.

Can anyone please tell me how the Thermo-Lite Bivy and the LAND/Shark bag compare? Is one tougher than the other?

Great question, I've been looking at both, trying to decide which one to order. I hope somebody out there has experience with both and steps up to the plate.

Troy

I find that most sleeping bags exagerate their temp rating. I aim for a bag that is rated at least 15 degrees warmer than the coldest conditions I expect to face.
A liner is a good idea that adds flexibility, but 15 degrees is the most it can add. Wearing insulated clothing when you sleep can help, especially insulated booties for your feet(which are great to have around camp, and almost a necessity for winter camping).

I've only direct experience with the Thermo lite, which is tougher than anything mylar, but not indestructible.

I really want to get a Land Shark and give it a going over. Sight unseen, my guess is it is about as tough a survival bag as your ever gonna come across in this day and age. I may just order one after Christmas. I'm thinking it must be of the same constituency as those HD survival blankets they sell for $12 to $15. If so, they will be bulkier than the Thermo lite, but pretty darned rugged.