I was mainly wondering if there is a difference of insulating qualities and toughness of the two. I have two LAND/Sharks in my BOB. They seem to be aimed mainly at water-based emergencies, the package stating "In water with life vest on, open Survival Bag allow Bag to fill with water and climb in." It also says they will burn if ignited (though I suppose all plastics will burn 'if ignited'). They have a drawstring closure and a clip to hook to others in the group to keep them from floating away from each other. They come sealed in a 'metalized' plastic package that must be torn open to use while the Thermo-Lite comes in a drawstring bag. That, to my mind, would make the Thermo-Lite more 'reusable'. Also, the Thermo-Lite comes in both a single and a double size. I've been thinking of putting a double-sized one in my BOB so if I'm with someone they can share it and if I'm by myself I can fold it in half and double the amount of insulation underneath me. Although I can't see myself floating around a large body of water any time soon, I can see myself spending an unexpected night out in the sticks (I live in east PA). I bought these thinking I could build a debris hut around them and ride out a storm in a little more comfort. (The sealed package of the LAND/Shark measures about 8x6.5x1.5".)

Carry the ThermoLite bivvy since buying couple of months ago, but haven't tested/used under actual conditions – just post-purchase inspection. Chose it for: weight; price; stuff sack; non-conductivity; "ventability."

Key facts on the three products I focused on: AMK TL Bivvy, the Land/Shark, and the Blizzard Survival Bag (similar to other two, but has its own unique features).

• Cost - Bivvy $22.95; Land/Shark $39.99; Blizzard $44.30
• Size - Bivvy & Land/Shark 36"x84"; Blizzard 88"x107"
• Packed Size - Bivvy 4 x6" (cylindrical); Land/Shark 8"x6"x1"; Blizzard 8.3"x4.3"x1.2"
• Packed Volume - Bivvy 75.4 cu.in.; Land/Shark 48 cu.in.; Blizzard 43 cu.in.
• Weight - Bivvy 6.5 oz; Land/Shark 18 oz; Blizzard 12 oz
• Conductive? - Bivvy no; Land/Shark yes; Blizzard yes (factor if you expect to encounter lightning)
• Stuff Sack - Bivvy included; Land/Shark $6.95; Blizzard $8.85
• Material - Bivvy ThermoLite 4-ply polyolefin; Land/Shark aluminized film laminated w/compositie reinforced ripstop material (like Benjammin said, material sounds similar to Space All-Weather Blanket ; Blizzard Reflexcell 3-layers of insulating air cells w/aluminum coating.
• Misc - Bivvy is softest & can be vented; Land/Shark appears to be most durable; Blizzard looks to have pretty good thermal efficiency and has body-hugging elasticized construction.

The hardest thing to quantify was the relative efficiency (under same conditions, which keeps you warmest?) of each; the manufacturers tend to not present their info apples-to-apples. I will say, the Blizzard offers some interesting performance comparisons. Is it just well-presented marketing hype? I don't know.

Thanks for the rundown, from the posts so far, I'm leaning toward the bivy myself, while stowing it between uses isn't an issue with me, and I,ve pretty much got the camo issue covered (netting, poncho, & liner), I'm getting the impression that the bivy is designed for repeated use, while the "LandShark" is more of a "use it in an emergency, then replace it" item. Anybody out there seen them side by side???

Troy

Great comparison(s), thanks!
Looks like the choice is still between the bivy and the "LandShark", and I'm still leaning toward the bivy, but just curious, if you were buying over, would you go with the bivy again, or try the "LandShark"?

Troy

I'd go with the bivvy again (and some of my reasons are admittedly subjective/personal preference).

I like its softness and flexibility. My sense is that the Land/Shark is less flexible, if I'm correct in assuming it shares physical characteristics with Space All-Weather Blankets, a couple of which I have; and the Blizzard Bag strikes me as being a little less durable. Let me hasten to add, I couldn't find the Shark or the Blizzard at local retailers to inspect first hand. Since I could the bivvy, the benefit of hands-on inspection tilted the scales a tad.

Also, having spent an eternity wrapped in a single-ply space blanket w/sleeping bag one night years ago (the sleeping bag I brought was a miscalculation on my part), the ability to vent the bivvy was appealing.

And while it's somewhat more bulky as purchased (loosely rolled in the stuff sack) than the other two, the cylindrical shape packs nicely in my fannypack and daypack (doesn't hurt that it's featherlight too).

On that note, I should have mentioned that I re-rolled the bivvy so it's tighter, then secured with two ranger bands before putting back in stuff sack. Now, its volume is pretty comparable to the other two.

I liked the non-conductivity. Certain times of year, Arizona can get unpredicatable thunderstorms, and the lightning can be a sight to behold. If I can carry something that won't increase my odds of getting zapped, that's good.

In the end, it was, "Each of them requires some compromises; which are less important to me?"

So short answer, yep, I'd buy it again. In fact, I could buy two for the price of one of the others. <img src="/images/graemlins/smile.gif" alt="" />

"buy two for the price of one of the others"
Yeah, I have to say, that's a pretty big selling point, and I haven't seen any thing to suggest that the 'Shark is THAT much more well made...and, considering that I'm not planning on using it "stand-alone", but as a liner/cover, I think I'll go with the bivy.

Thanks again,

Troy

I just read a story of a guy using the Bivy Bag by pulling it on over his head, up-side-down, and using the foot vent to breath through...
That might work!

Great ... Cold weather survival meets haloween <img src="/images/graemlins/smile.gif" alt="" />