Companion forum thread to:

Marmot Hydrogen Sleeping Bag Review

Thanks for the review Will. It seems that the hydrogen and the wm megalite are more similar and a closer comparison than the summerlite. The manuf.specs for the megalite are 24 ounces total weight with 12 ounces of down and a girth of 64"/55"/39". They both have a full zipper too. I am a megalite user and like the width in the shoulders, though I have been tempted to squeeze into a summerlite for the weight savings.

Great, thorough review, Will. As usual.

I have the Hydrogen Long and really like it. Of the 7 bags I've used/owned in this temp range, Marmot's ranks among the finest. Well designed and superbly-executed construction. But, boy does that white zipper stand out!

Thanks, Will. I'm using a Long Hydrogen right now, and though I've been tempted to downgrade to something lighter, I can't really find a compelling replacement. This review confirms what I've seen - there are lighter options, but the Hydrogen remains a solid choice.

Emmett, I've had a similar thoughts and always end up keeping my Hydrogen. I have a 2007 model with the 1/2 zip, and love it. I wish it had a narrower cut (and I knew about narrow cuts when I bought the bag), but alas.

Will, I love the comparison test. Come to think of it, these kinds of technical tests are pretty much my favorite thing about BPL articles. Anyone can do a subjective spend-a-night-in-the-sleeping-bag test, but it takes a much more creative mad scientist to think of sticking a pan of hot water in your sleeping bag. Cheers!

Your mad scientist characteristics are what really set you and your reviews head and shoulders above the rest of the reviewers! Keep up the quantifiable differences!

I bought a Hydrogen five years ago. It was black, not that awful vomit green! The problem was that for shoulder-season camping, it just wasn't warm enough! I put on all the insulating layers I had inside it, and I shivered the whole night (25*). I sold the Hydrogen and bought a Western Mountaineering Ultralight Super, and have never regretted it!

My wife just gave me a Hydrogen for Christmas - looks like she choose well!

Nice bag. But for me, being of the wider sort, the MB would work better. Given that I carry a Cocoon Hoody anyway, I could just layer in to push the temps. 1/2 a pound difference and almost $100 is significant given that there is the option of using gear you are already carrying to increase warmth.

What accounts for the curves crossing at about 11:40? It looks like for the first hour the 125F water is heating up the tub and sensors. But if the Hydrogen is loosing heat slower it should of heated up the gear quicker. Is there a thermoconductivity change with time or temperature?

I purchased a Summerlite reg. and while the weight was certainly attractive, it was just too tight for me (6' 200#)- I ended up trading it with a member for a Hydrogen reg.- I think we both ended happy :)

Great write-up Will!

I have 3 Marmot bags and hate the fact they axed the Pertex Quantum they previously used. I remember using the Lithium with the P.Q. and woke up with a puddle over my chest, and ice from the gut down and the fabric was bone dry without a hint of wetting through.
I had my daughter's cat make a play-toy out of my 0-degree Lithium and had to send it in to be repaired only to see patches made of the ghastly new fabric.

Hi all, thanks for your comments. Here are some individual responses:

David: You're right, a better comparison would be with the WM MegaLite. I was thinking in terms of the lightest bags and overlooked the MegaLite as being a closer comparison. Sorry for that. Weight-wise, the MegaLite is the same as the Hydrogen.

Mark: Good observation on the curves crossing. I don't have an explanation and am still thinking about it. I ran the test twice and got similar results, so something is causing the difference in warm up. For my State of the Market report on UL 3-season down mummy bags, to be published this spring, I plan to run comparison tests using a regulated heating pad inside, and maybe that will work better. It will be a "poor man's mannequin test" to produce some Relative Warmth data, similar to Richard Nisely's tests.

Best regards and happy hiking,
Will