Time to replace my lifejacket

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Hello All

It's time to replace my lifejacket and the model I want has both "automatic" and "hammar" options.

In simple terms what is the difference in systems?

Thanks

Sandy
 
Automatic lifejackets inflate when the mechanism gets wet enough to soften a little tablet, allowing a spring-loaded plunger to puncture the gas cylinder. This is good in theory, but I've had one inflate on me in the cockpit in torrential rain.

Hammar lifejackets need the mechanism to be actually immersed, by more than 10cm, before they will inflate. Theoretically, if you were floating on your back, it might not inflate automatically.
 
pvb said:
Automatic lifejackets inflate when the mechanism gets wet enough to soften a little tablet, allowing a spring-loaded plunger to puncture the gas cylinder. This is good in theory, but I've had one inflate on me in the cockpit in torrential rain.

Hammar lifejackets need the mechanism to be actually immersed, by more than 10cm, before they will inflate. Theoretically, if you were floating on your back, it might not inflate automatically.
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Brilliant, that is the detail in needed.

Hammar it is then.
 
The automatic life jacket systems are now very reliable and not prone to going off after a soaking, they tend to need more water then you’d get from rain or a wave breaking over the boat.
The downside of the Hamar system is it’s cost. It needs replacing every x years and the kit is in the order of £50 as opposed to £20 or so for the dissolving tablet type. In addition, the hammar mechanism lives inside the life jacket bladder and is a pain to remove and refit in comparison to the dissolving tablet type.
Otherwise, not much to choose between the two, I did once have a hammar life jacket but gave it away because of the costs and hassle of servicing it.
 
duncan99210 said:
The automatic life jacket systems are now very reliable and not prone to going off after a soaking, they tend to need more water then you’d get from rain or a wave breaking over the boat.
The downside of the Hamar system is it’s cost. It needs replacing every x years and the kit is in the order of £50 as opposed to £20 or so for the dissolving tablet type. In addition, the hammar mechanism lives inside the life jacket bladder and is a pain to remove and refit in comparison to the dissolving tablet type.
Otherwise, not much to choose between the two, I did once have a hammar life jacket but gave it away because of the costs and hassle of servicing it.
Click to expand...

Agree..... I got rid of my Hammar ones years ago as too expensive to maintain and no better now than the modified tablet type.
 
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In the last five years I've had an automatic one go off all by itself in the boat!

While the hammar appears to be more expensive to replace the kits the difference is not that great.
 
Sandy said:
In the last five years I've had an automatic one go off all by itself in the boat!
Click to expand...

I wonder if the reputation of non-hammar firing mechanisms is based on older devices? I bought a new spinlock deckvest this year. I bought the hammar version for the usual reasons but then regretted it: I realised that in 11 years of ownership of my old "pro-sensor" deckvest I'd been in torrential rain and been dumped on by green water on the foredeck numerous times and never had the mechanism accidentally fire.

So did the lifejacket you had which went off accidentally have one of the newer style United Moulders mechanisms?

duncan99210 pointed out both the cost and hassle of removing the hammar mechanism. You can't simply unscrew the cylinder for a flight, you have to remove the mechanism. OK not too much bother with practice but it's added hassle.

If I had to choose again I'd go with the pro-sensor version
 
laika said:
I wonder if the reputation of non-hammar firing mechanisms is based on older devices? I bought a new spinlock deckvest this year. I bought the hammar version for the usual reasons but then regretted it: I realised that in 11 years of ownership of my old "pro-sensor" deckvest I'd been in torrential rain and been dumped on by green water on the foredeck numerous times and never had the mechanism accidentally fire.

So did the lifejacket you had which went off accidentally have one of the newer style United Moulders mechanisms?

duncan99210 pointed out both the cost and hassle of removing the hammar mechanism. You can't simply unscrew the cylinder for a flight, you have to remove the mechanism. OK not too much bother with practice but it's added hassle.

If I had to choose again I'd go with the pro-sensor version
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Thanks liaka

Can't really answer the question about the new United Moulders mechanism, the jacket was a Crewsaver 190N. Arrived at the boat one day and the LJ was sat fully inflated on my bunk.

I get my LJs professionally serviced and have no intention of flying with them as it is more hassle than its worth.

The Boat Show is next month and I'll have a chat with the lovely people from Crewsaver. I'm not a fan of Spinlock after attempting to inflate one of their jackets at the LBS a few years back and found out that I needed arms 1.5 meters longer than the ones I have; a serious design flaw should you ever need to manually pull the toggle.
 
Sandy said:
The Boat Show is next month and I'll have a chat with the lovely people from Crewsaver.
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Definitely your best bet! The crewsaver folks at least year's Southampton show were really knowledgeable.

fwiw I've just been reading about the difference between the MK5 and pro-sensor and from the accidental inflation point of view, if I'm reading it right, they should be the same.

Reminding myself about how these things are activated suggests that storing them upright is the way to go to avoid the risk of a spill (or condensation?) running *down* onto the sensor (they're activated by water coming "up" from below)
 
I have four hammar jackets and would buy UML to replace them. The hammar has no tangible benefit to me, costs more to service, can’t have the cylinders weighed (they’re glued into a special hammar plastic piece that adds to the weight stamped on the botttle - also means you can’t buy standard bottles as spares) and has the potential for a leak on reassembly if you don’t seat the mechanism properly in its large hole in the bladder.

Pete
 
Regarding the water activated cartridges accidentally activating, it is not something that is heard of, except rarely, so I am not sure it such an issue to decide one way or the the other. The ones I have just received will expire June 2022, so thats a £1 a year, maybe I am getting a year old batch.

https://www.cmhammar.com/products/personal-safety-mob/lifejacket-inflator/ Hammer states a 5 year service interval and costs £27 https://www.lifejackets.co.uk/products/533/hammar-m1a1-operating-head-2023-expiry so thats just over a £5 per year. Hardly bank breaking stuff.

The water cartridge type are more common. Anyway, this is just an exercise to satisfy myself, not a recommendation one way or the other.
 
prv said:
I have four hammar jackets and would buy UML to replace them. The hammar has no tangible benefit to me, costs more to service, can’t have the cylinders weighed (they’re glued into a special hammar plastic piece that adds to the weight stamped on the botttle - also means you can’t buy standard bottles as spares) and has the potential for a leak on reassembly if you don’t seat the mechanism properly in its large hole in the bladder.

Pete
Click to expand...

One of the service company you tube videos gives the weight of the firing mechanism and they show the weight on the scale, subtract the mechanism weight and get the bottle weight as stated on the bottle. They then use that as good test and reassemble the jacket. Worth knowing if you do self service.

Here is the link https://www.youtube.com/watch?v=oixSmcv0zRc
 
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As we are advised too swim on our backs to avoid drowning, this might defeat the hammar mechanism. A number of fishing boats using hammar release on liferafts had liferaft that didnt inflate when boat sank, though that could be failure of "cord cutter' knife (I trawl thru MAIB reports monthly but cant remember which years or boats).

Salt tablet works fine and though I have had accidental inflation when beached dinghy filled with water, that probably could have happened with hammar also, my fault for not pulling further up Lundy slipway. The old one that went off in locker was 10 years old so my fault entirely again as should renew release much more frequently. Easy to carry spare cylinders and spare releases for the salt tablet kind
 
oldmanofthehills said:
As we are advised too swim on our backs to avoid drowning, this might defeat the hammar mechanism. A number of fishing boats using hammar release on liferafts had liferaft that didnt inflate when boat sank, though that could be failure of "cord cutter' knife (I trawl thru MAIB reports monthly but cant remember which years or boats).

Salt tablet works fine and though I have had accidental inflation when beached dinghy filled with water, that probably could have happened with hammar also, my fault for not pulling further up Lundy slipway. The old one that went off in locker was 10 years old so my fault entirely again as should renew release much more frequently. Easy to carry spare cylinders and spare releases for the salt tablet kind
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The way I see it, if I am "swimming on my back" I am fully conscious and can pull the manual inflation toggle.

The automatic system is when I am not conscious and the jacket needs to do it all by itself.
 
I've got Seago 190 Active Pros (imo best extras for the money, spray hood light etc and a bladder design meant not to drown you with wave action from in front) which use the UM mechs. Until recently I've opened them up and taken the mech out to rinse and dry the ljs after wet sails, but recently I've been hanging them the right way up and just spraying them hard in the shower. So far.... they haven't inflated.
 
anoccasionalyachtsman said:
I've got Seago 190 Active Pros (imo best extras for the money, spray hood light etc and a bladder design meant not to drown you with wave action from in front) which use the UM mechs. Until recently I've opened them up and taken the mech out to rinse and dry the ljs after wet sails, but recently I've been hanging them the right way up and just spraying them hard in the shower. So far.... they haven't inflated.
Click to expand...

If you look at how the bobbins are constructed (on both UML and Halkey-Roberts) you’ll find that they are made so as to require the bobbin to be flooded rather than just wetted. That means that, generally speaking, unless you immerse the mechanism in water, they won’t go off. Prolonged storage in very damp conditions might cause the bobbin salt tablet to disintegrate but it’s not likely.
 
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