The problem with the salt tablets (and I've also heard it called aspirin, I'm not sure exactly what who uses) is that they can and will absorb moisture from the air and then one day...whoosh! the inflator goes off, leaving you shy about $30 for a re-arm kit, and worse, leaving you without anything except your spare (you did pack a spare, right?) while the vest has inflated and jammed itself against spiky things in a closet.
They're all fairly well protected from rain and splash from what I've seen, although on my PFD and BC I've tucked the manual inflation ball way up so it can't snag on anything and accidentally manually inflate. (If I need to pull that, I can stay afloat long enough to deal with it, or find it on the way down.)
From the Hammar web site:
"The Manual/Automatic version works like this:
When the Inflator is lowered more than about 10 cm in the water, the hydrostatic valve opens and lets the water meet the water sensitive element that in turn releases a stainless steel coil spring. The spring then drives a needle into the end of the gas cylinder, which is now punctured so that the gas instantly fills the lifejacket.
Total buoyancy is often reached within 4 - 5 seconds."
It sounds like the Hammar inflator is really the Crewfit type (paper mache over a compressed coil spring) and they've enclosed the whole bit in a sealed pouch with a weak one-way valve, so that the water can't come in until there's a real submersion. A clever extension of an idea--I couldn't figure out why they were calling anything that inexpensive a hydrostatic inflator, since water pressure itself isn't really inflating anything.
I don't mind a bit of thread drift at all--as long as we're on PFD's.
Last edited by hellosailor; 06-13-2007 at 03:18 PM.