Fire and forget one time blob

[Matt-75]

Firstly im not an engineer or similar. My field is computers. I have neither the money or the time to develop a project such as this, so i will just publish ideas for now.

My idea would be along the lines of a self inflating blob on say 100m of line that would activate after 30-60 mins of inactivity. It would inflate and head to the surface, and then send out a radio signal (like a locater beacon). The powering of the device could be by batteries and a kinetic mechanism similar to the sports watches that power themselves as you move (the sea moves a lot, so their shouldnt be a shortage of power).

How to safeguard against a misfire, would be accomplished by taking samples of movement gauged by a mechanism that could detect movement (rocker switch or something similar), over a period of time. Also maybe some method of detecting body heat could be used, as after death the body cools off a lot. If no movement is detected after the time limit that is set, and the body temperature is not what it should be, the blob would fire and start transmitting.

To find the body would require enough boats or aircraft to triangulate the signal. Also recovery of the body may require either a diving team or a DSV, but those factors are outside the spec of my idea.

This is idea is only aimed at recovering bodies, and not particularly at tracking people, although with some modification, it could probably be used for both.

[Richard Whitcombe]

Id be very scared with the prospect for accidental inflation firstly through faults and secondly with it misreading things.

Diver nice and trimmed out and stationary on a deco stop when 3 minutes in, BANG. Someone kneeling on the bottom doing skills or some survey work not moving. Same thing.

Im not sure this solves a problem that actually exists.

[TerryH]

Few years ago long before DSMB's were a must have, I remember what
I think it was a Beuchat product of an DSMB with a parachute type cord.
Wasnt a reel, just a line looped in such a way that it deployed same as one.

Best bit was that it was extremly compact and easily stowable. Now that
would be an excellent addition to every BC.

[Chris aka divingchef]

Id be very scared with the prospect for accidental inflation firstly through faults and secondly with it misreading things.

Diver nice and trimmed out and stationary on a deco stop when 3 minutes in, BANG. Someone kneeling on the bottom doing skills or some survey work not moving. Same thing.

Im not sure this solves a problem that actually exists.

Yepp
A bit like the German mine laying subs, drop the anchor and mine in a soluble casing and leave !! except some went off under the sub and "home goal" was heard throughout the RN

[David Walker]

So, this is a body recovery mechanism? To be honest, it seems like a huge risk (carrying around something that could trigger accidentally and blat you to the surface) just to aid the recovery of your dead body. Thinking back to incident reports, the cases of divers who are suspected dead and cannot be found are very uncommon - where as the number of incidents of kit malfunctioning, people getting tangled in DSMBs, etc are much higher.

Nice thought, but the risks outweigh the practical benefit.

David

[PeteM]

So, this is a body recovery mechanism? To be honest, it seems like a huge risk (carrying around something that could trigger accidentally and blat you to the surface) just to aid the recovery of your dead body. Thinking back to incident reports, the cases of divers who are suspected dead and cannot be found are very uncommon - where as the number of incidents of kit malfunctioning, people getting tangled in DSMBs, etc are much higher.

Nice thought, but the risks outweigh the practical benefit.

David

This is in the DiveTrack forum which is specific for discussion of this type of thing

[David Walker]

This is in the DiveTrack forum which is specific for discussion of this type of thing

Oh right, fair enough, can't say I ever notice what forum i'm in.

However, the point still remains that benefit must be balanced with risk, and if this is going to be an electronically controlled air source, controlled by an imprecise sensing capability and attached to the diver, then the potential risk is huge!

David

[TerryH]

Id be very scared with the prospect for accidental inflation firstly through faults and secondly with it misreading things.

Diver nice and trimmed out and stationary on a deco stop when 3 minutes in, BANG. Someone kneeling on the bottom doing skills or some survey work not moving. Same thing.

Im not sure this solves a problem that actually exists.

It might work if you had a line with a guaranteed break. Just enough to
let go, but not enough to take anybody up.

Or

If its just a marker than why does it need that much lift?
How about just a sealed air chamber, very small and with a pinger in it.
If that released in error, then it would get to the surface and then start
signalling. No way it would take anybody up.

The line only has to be able to followed so doesnt have to be thick.

The pinger itself might not have to be that involved. Maybe just enough
to reach a receiver on the boat.

Or how about a strobe attached.

All depends what exactky we are trying to acheive. A warning signal or an
after the fact signal.

[Neil R]

Hi all,

Ok the idea's a good one but has already been pointed out movement isn't an ideal way of measurement.

What about something along the lines of a cylinder pressure switch with a setable delay fire of the smb?

Uwatec do a digital pressure gauge so something along these lines that realises the the cylinder presure hasn't changed in a determined time and this then sets in motion a count downtime for the smb to be fired.

this way you can say the pressure hasn't changed for " X mins " and the countdown has " X hrs " before it fires the blob.

Doing it this way if your doing a deep dive with gas switching and long deco stops you should have allowed enought time to return to the surface and turn the unit off before it fires.

Thoughts ?

[Finless]

Hmmmm, I have to say this is not product that I think I would use ........... auto firing based on time and/or lack of motion.

As a sometimes solo diver I suppose the recovery of my body in the event of a fatal incident may be of comfort to the family but .....................

I suppose an EPIRB working on a timer that was detectable from the surface could be an option?

Anyway, given the probable cost, I couldn't see it being a popular item amongst the general diving populace?

[Matt-75]

I've actually been in here a few times since JimW set it up, and no one has posted any ideas. Which is a bit astounding since we have so many divers on this forum, who i would have thought would have at least some ideas.

So i thought i'd post something in here and try and get everyone to add some ideas. Most may be like me, and have neither the time nor the money for developing something like this, but if someone took one of my ideas and created something that saved lifes or helped recover lost divers, then i'd consider this time well spent.

This is my first idea, i will now take on the advice of you guys, and try to think of a new one.

But for me, what seems to be needed is something that is pretty much automatic. Maybe a failsafe button somewhere that has to be pressed every 30 minutes would overcome the deco scenario.

The aim of the idea wasnt to lift the diver, just mark the spot. The diver remains wherever he was when it deployed, the only difference is something up top is now transmitting your location, which thinking about it would be nice as a warning to ships and other vessels to stay away if you were doing deco. But is more their so your friends can locate you.


I suppose the wording is wrong. Blob is more for lifting, and i just meant any sort of visual marker. After re-reading through, Terrys idea of a small air chamber is a much better idea i think.

[Vic]

My idea would be along the lines of a self inflating blob on say 100m of line that would activate after 30-60 mins of inactivity.

Aside from the issues raised by other posters, this ignores the very first requirement of the specification :-

· A device capable of providing a response to an acoustic signal from a standard echo sounder.

It would inflate and head to the surface

If this is going to be tethered to the diver, that's a whole lot of string.

To develop a signalling system that works at depth of up to 200 metres

That means you're going to need at least 300m of line stored in a way that isn't going to birdsnest on deployment. And we haven't even started on penetration dives yet...

and then send out a radio signal (like a locater beacon). The powering of the device could be by batteries and a kinetic mechanism similar to the sports watches that power themselves as you move (the sea moves a lot, so their shouldnt be a shortage of power).

I think you'd have trouble generating enough power to drive an omnidirectional radio transmitter from a package small enough to be carried by a diver...

Vic.

[Vic]

Uwatec do a digital pressure gauge so something along these lines that realises the the cylinder presure hasn't changed in a determined time and this then sets in motion a count downtime for the smb to be fired.

Deco mixes?

Vic.

[Vic]

no one has posted any ideas. Which is a bit astounding since we have so many divers on this forum, who i would have thought would have at least some ideas.

I don't think it's at all surprising. The spec is fairly tight - i.e it needs to be a battery-operated sonar device that will work for 2 months at 10C and withstand the pressure at 300m, and still cost about £150.

I'm quite sure I could knock something up with a target price of about £15K, but that's outside spec. To bring it in at £150 is going to require *monumental* volumes.

So that's why I haven't posted anything - I can't do it.

VIc.

[TerryH]

I think you'd have trouble generating enough power to drive an omnidirectional radio transmitter from a package small enough to be carried by a diver...
Vic.

Ok how about this for a late bit of nonsense thinking.

You have a cylinder etc that is solid (wont crush), but positively buoyant.
If you let it go it goes to the surface. Inside is a very low power transmitter
that puts out a ping and activates in air. The whole thing is attached to the
diver via a very thin line which either unravelles or is parachute style.

Now you are wondering how this is deployed?

The whole cylinder fits in another cylinder which is fixed to the BC shoulder
in the same way as a strobe. This is made out of an enviromentally friendly
product which disolves. You would be able to buy very cheap sleeves with
different time ratings. Ok you have to buy one each dive, but it wouldnt
cost much more than a jiffy bag.

So you have a dive for 1 hour, then have a 1.5 hour tube.

Could even have a marker die in it so when it hits the surface that starts
coming out as well.

Like I said its late (or its early), but it is an idea.

[Woz]

I would just leave the body for the fishes, myself.

[Ben Panter]

I think that there is a simpler version for firing the thing - I usually know to within a few minutes how long I will be diving for, double it and set a timer. If I plan to be up in 45 min I set the timer for 1:30. If I'm (for the purposes of illustration) doing a 4 hour trimix dive then I set it for 6 hours.

Again, it's a body recovery device.

Ben

Ben

[Finless]

I think that there is a simpler version for firing the thing - I usually know to within a few minutes how long I will be diving for, double it and set a timer. If I plan to be up in 45 min I set the timer for 1:30. If I'm (for the purposes of illustration) doing a 4 hour trimix dive then I set it for 6 hours.

Again, it's a body recovery device.

Ben

Ben

Surely you mean 90 minutes?



:)

[AndyDavis]

Hmmm....I wouldn't be that concerned about the recovery of my body if I died in the water. I'd rather fill that pocket space with something that may help me survive in the first instance.

[Wadey]

Here is my idea

you use the floaty cylinder thing but have a clip with a magnetic actuator like the ones you get on doors to stop them opening, to release it from its housing which is attached to your bcd. Battery power isnt an issue for a device like this as it requires very little power to undo the clip. The cylinder would probably need to be sprung somehow so that if the diver is in a position where the device is upside down or on its side it will still eject from the housing. The power to make the device transmit would be the tricky thing and also quite expensive although i've got a mobile phone that transmits for days and its only 6mm thick so batteries are getting much better. To activate the device the spring mechanism could also be a switch that turns the device on and starts transmitting. it would probably only need to work for an hour or two as when the diver didnt return on schedule people would be lookingfor them anyway. and be in the area to find the transmitter.

the line would also be held inside the housing and would spool from it as the device floated up. it would have to be very thin line to get a few hundred meters from it and alo quite strong. something like fishing line would be ideal. but the length would still be tight. perhpas making a longer tube maybe 2 baked bean tins in size.
Anyway thats my idea.
can't see it catching on though

I'm so bored at work can't believe I put so much thought into that.