Thanks, guys, for obliterating my skepticism on this topic. I am convinced that a Screamer is beneficial, especially if you're tethered to a fixed point that has no give.
How about if you're tethered to a synthetic (polyester or nylon) jackline? Does the guitar-string effect provide sufficient flex to avoid it? Or is this a situation where you do both for greater certainty that the harness won't break your ribs?
Not sure how to confirm it with experience, other than strictly anecdotally...
The more direct way to ask the question is, has anyone here actually had a pill-type PFD inflate when it should not have (aside from accidentally pulling the cord) due to rain or other transient water?
I'm still debating whether to get a separate harness for with my pill-type PFD (which is very comfortable) or upgrading to a Mustang HIT-type with D-rings. If the HIT provides a confirmed benefit (vs. theoretical speculation) it might seal the deal.
Not all automatic models use the same automatic inflator. AirForce ® by Mustang automatic inflation PFDs are designed so that they have to be immersed in water before the inflation mechanism can be set off. The device is, however, susceptible to accidental inflation if repeatedly exposed to a humid or damp environment
I have no personal experience with activation of automatic inflatable PFDs because I wouldn't have one aboard my boat. I know I'm in the minority here, but I'll try and explain why I thing auto-inflation is a useless feature and potentially dangerous.
1: Is there any benefit to auto-inflation? The main stated benefit of the auto-inflation feature is that it will inflate if you go overboard unconscious. True, it will inflate if you're unconscious, but you are still dead. Most of the inflatable PFDs put the unconscious victim's mouth/nose FOUR INCHES above the water. Since you're unconscious you can't protect your airway. If a couple of >4" waves come along (like during your rescue) you drown. Mustang survival has created a $400 exotic inflatable vest that they brag will keep your mouth "up to" 9" above the water. Still not much. For me, the "benefit" of helping an unconscious victim survive is a myth. Therefore, they have no benefit over manual inflation that I can see.
2: Is there any downside to auto-inflation? I would say yes in both safety and expense/convenience. I feel comfortable as a swimmer in the water, and I might like to be able to swim as part of affecting my own rescue. I can imagine (rare) scenarios like an upturned dinghy, or being caught in lines underwater, where the inflation could lead to your drowning. More likely, I imagine scenarios like falling overboard and wanting to be able to swim over to the MOB pole, cushion, or line/lifesling that was thrown to you before activating your flotation. Swimming with an inflatable PFD is not like swimming with a type III. They turn you on your back and make it nearly impossible to swim. Not being able to swim immediately to help your own rescue make the auto-inflate vests more dangerous in my book.
Then there is the downside of maintenance and accidental inflation. Accidental inflation happens, often. I worked at a West Marine for a summer to pillage their discount during a refit (highly recommended) and on the days I worked we sold a dozen re-arming kits over a the summer. I asked EVERY PERSON I sold one to how it inflated. All were accidental/unintended, though more than half were from wet gear in a bag (often destroying the bag). Buying and replacing the re-arm kits, keeping a supply of them aboard (and keeping them dry!) during a tropical cruise, sounds like a pain, and an expensive one. Having one go off on you while you're working (like a fellow racer in the Round the County 2011) on deck doesn't sound good either.
Long live manual inflation! If I had to pay more for manual inflation as a feature, I would.
Very well put. I have a couple of manual lifevests, and I figured that although they won't save me if unconscious, they won't accidently go off. However, I hadn't thought of it to such detail as you put it in your posts.
I guess wearing a skater helmet if really tossing about might actually be better (getting bashed into a pulpit or coaming) than an auto-inflate lifevest. Not that you'll catch me wearing a helmet under normal circumstances.
A British sailing magazine did tests on harnesses, by traveling at 4 knots and having the person in them jump overboard. The shock from the tug, when the tether came tight, was minimal. ,With the tether attached to the chest, the person being towed had such a huge bow wave build up in front of him, that it was impossible for him to breath and it threatened to drown him quickly. That happened in a recent Farallons race, and the person drowned before his crew could slow the boat down enough for him to breath, or get his head above his own bow wave. That should have resulted in a law suit against the manufacturer of the harness. They would be building them very differently today, had that happened. It's just a matter of time before such an incident results in a huge law suit.
Next they tried attaching the tether to the back of the harness. That kept the occupant alive , but made it impossible for him to pull himself back in.
Then they tried attaching the tether to the shoulder. That not only allowed the occupant to breath , but it also allowed him to pull himself back in. That was the best option, the one I use.
Manufacturers of safety harnesses don't do any such testing, they just copy what everyone else does.
I have eliminated the D rings, for a lashing, as they are far more comfortable in your bunk. Attaching the tether to the top of the shoulder also stops it from digging into you when you are single handed, and in your bunk on a squally night.