Wearable personal alarm that sounds & flashes when immersed in water

[Llamedos]

3 hours ago, Yank on the Cut said:

People are very disoriented when they fall in due to the almost inevitably cold water, the bewilderment, the initial desire to simply hang on to whatever is at hand (if anything),  the panicked shouting which may or may not reach someone's ears.  An alarm triggered by immersion (or indeed a fall alarm that is waterproof) with light and sounder would be a great asset.

After seeing what happened to the chap I pulled out of our Marina, I think I agree with you. Apparently he falls in regularly - he’s one of those people who’s naturally clumsy. Probably should be nowhere near a boat at all, but clearly, falling in hasn’t put him off!

Edited April 16 by Llamedos

[wakey_wake]

5 hours ago, Yank on the Cut said:

An alarm triggered by immersion (or indeed a fall alarm that is waterproof) with light and sounder would be a great asset.

 

I have not searched the long tail of the online markets, but I've never seen or heard of such a thing.

 

I agree that it could be useful, but I believe part of the solution has to be a standardised noise. That would need an education campaign, unless the sound was "characteristic shouting and splashing like the movie depiction of drowning".

 

...in much the same way that red LEDs flashing at around 2Hz now are characteristically the back of a bicycle. That came from new technology being eventually recognised as road legal, and all road users seeing a lot of them around (before they were sufficient as road legal per se) because they are better than the previously road legal lamps. Part of this story is found in WP: Bicycle lighting around the mentions of BS 6102.

 

 

4 hours ago, Jen-in-Wellies said:

I am not sure a reliable alert beacon can be made. Where would you wear it? If in a pocket, or round a waist, nothing will be heard, or seen, if you fall in, unless it can deploy to the surface reliably.

I'm sure it can be made, but the questions seem to be "what should it be like?" and "did we want to design it by committee right here in the thread?"

 

It will be easier if it's a single unit, rather than two or three units with a radio link or cable between, but something that threads through the belt loops of trousers could work well as a sensor. Requiring conduction from left hip to right hip should prevent false alarms due to rain.

 

It needs a battery and a sounder, and it's best if the sounder doesn't also deafen or further shock the dunkee. Water conducts some sounds quite well so perhaps the answer is to signal (ultrasonically?) through the water back to the boat and have the sounder on the boat.

 

@Yank on the Cut obviously you want it to work any place it becomes needed, but did you envision it being effective around known boats or other infrastructure? Or functioning ten miles from anywhere along a canal, in hopes of finding a dog walker?

 

 

4 hours ago, Jen-in-Wellies said:

CaRT elf'n'safety rules say their employees, contractors and volunteers have to wear self inflating life jackets when near water.

EA are the same. See three people with matching Crewsavers? That will be EA checking the boat licences.

 

Companies are in a very different position to OP. The staff are on duty, sober (probably drove there) and the SOP is for there to be two or more of them for their mutual safety. It's a good thing there is a willing band of customers to fund this nice safe setup! 😕

[LadyG]

Water activated lights on lifejackets are potentially usefull at sea at night, if someone falls in., but they may not be long lasting and reliable if used in a damp atmosphere,which is more than likely for yachtsmen or fishermen.

There are  more substatial lights, and  Epirbs which operate with a mercury switch, the gadget floats in water light upwards,  with the light enclosed in a waterproof casing. They last for many hours when floating.

Edited April 16 by LadyG

[BilgePump]

18 hours ago, LadyG said:

There are  more substatial lights, and  Epirbs which operate with a mercury switch, the gadget floats in water light upwards,  with the light enclosed in a waterproof casing. They last for many hours when floating.

EPIRBs should be registered under a ship radio licence if I recall correctly. Comes under the VHF licensing which is really for non-inland boats. My trainer was MCA chap and told of us a party near the coast where some kids had lobbed one into the swimming pool, loving the way it lit up and floated but not that popular when a search and rescue helicopter turned up overhead.

[Alan de Enfield]

1 hour ago, BilgePump said:

EPIRBs should be registered under a ship radio licence if I recall correctly.

 

 

But PLBs do not.

They are registered, (but not licenced) with your details and work anywhere in the world- land, sea or air.

we have them for scuba diving / hiking / horse riding in the 'wilds'

 

Notification can get to your local rescue services within 5 minutes

Cost " a couple of £100" and battery last 5 years minimum and is replaceable, no subscription, licence or call charges.

Accurate to about 1 metre.

 

 

 

 

 

 

Edited April 17 by Alan de Enfield

[LadyG]

2 hours ago, BilgePump said:

EPIRBs should be registered under a ship radio licence if I recall correctly. Comes under the VHF licensing which is really for non-inland boats. My trainer was MCA chap and told of us a party near the coast where some kids had lobbed one into the swimming pool, loving the way it lit up and floated but not that popular when a search and rescue helicopter turned up overhead.

Im not suggesting anyone uses an Epirb, or a light which is designed to attach to liferings. These are large, and no use on the inland waters. They are designed and manufactured to be fit for purpose, not for use on canal boats.

 

 

 

Edited April 17 by LadyG

[wakey_wake]

https://www.force4.co.uk/department/safety/epirbs-plbs-ais-units/personal-ais-units has handy descriptions of the differences between EPIRBs, PLBs and AIS.

 

I've not read up on the costs and obligations of owning one of these, because I don't plan to get one. The up front costs are shown in the shop but the obligations and possible fines (?) for misuse may be documented elsewhere.

 

Triggering an EPIRB during beer-assisted folly seems like it would be an abuse, but at what point does it become valid? "Well in hindsight I see it was idiotic to walk along the gunnels in my slippers and wearing a heavy coat, but a strange noise woke me up and I was groggy. I'm sure glad you fished me out before I drowned because there was nobody else around!". For me part of the answer has to be whether the dunkee changes their behaviour afterwards, to reduce the risk of recurrence; and therefore also whether they've taken steps beforehand to address the foreseeable risks.

 

Comparing the 'big red button telephone' which I believe are proprietary / commercial / subscription based semi-emergency response services, such as https://redbuttontelecare.co.uk/ (first search hit that looked relevant). The one I've seen went through to a call centre, where a human would know your name and expect to hear you describe the problem. If you didn't respond they called 999 for you.

 

Once that big red button is pressed, a chain of events is set off. You can cancel it before it finishes dialling but otherwise the company wants to hear from you, and the one I saw was happy for the button to be pressed a few times a month to reassure everyone that the system worked.

 

My understanding of any emergency service callout is that it's irrevocable. You ask for a fire engine? They will come and check there is no fire, and if that was an abuse then you're in trouble.

 

If the use case is marina-wide then there seems to be a niche for devices to attempt to organise a local response before escalating to emergency services. So back to the question, what is a sensible thing to fill that niche? And @Yank on the Cut, is that the question you wanted raised?

 

AI powered devices are coming into existence for this niche. I presume they seek to cut out the human from the 'commercial subscription call centre' and make the decision to escalate to emergency service callout by applying a 'giant spreadsheet of carefully chosen numbers'. At least the emergency services have a central organisation to negotiate with if it does stupid things.

[gatekrash]

5 hours ago, wakey_wake said:

 

My understanding of any emergency service callout is that it's irrevocable. You ask for a fire engine? They will come and check there is no fire, and if that was an abuse then you're in trouble.

 

Certainly as far as the Coastguard goes if we're paged to something then we'll respond, if the first informant then calls back and says actually it isn't an emergency then we'll usually still proceed and make sure. A lot of our shouts are "FAWGI's" - false alarm with good intent.

The only time we stand down en route usually is if we're responding to a call for assistance from police / ambulance and they then tell us the job is resolved.

[Yank on the Cut]

On 17/04/2026 at 12:23, wakey_wake said:

https://www.force4.co.uk/department/safety/epirbs-plbs-ais-units/personal-ais-units has handy descriptions of the differences between EPIRBs, PLBs and AIS.

 

I've not read up on the costs and obligations of owning one of these, because I don't plan to get one. The up front costs are shown in the shop but the obligations and possible fines (?) for misuse may be documented elsewhere.

 

Triggering an EPIRB during beer-assisted folly seems like it would be an abuse, but at what point does it become valid? "Well in hindsight I see it was idiotic to walk along the gunnels in my slippers and wearing a heavy coat, but a strange noise woke me up and I was groggy. I'm sure glad you fished me out before I drowned because there was nobody else around!". For me part of the answer has to be whether the dunkee changes their behaviour afterwards, to reduce the risk of recurrence; and therefore also whether they've taken steps beforehand to address the foreseeable risks.

 

Comparing the 'big red button telephone' which I believe are proprietary / commercial / subscription based semi-emergency response services, such as https://redbuttontelecare.co.uk/ (first search hit that looked relevant). The one I've seen went through to a call centre, where a human would know your name and expect to hear you describe the problem. If you didn't respond they called 999 for you.

 

Once that big red button is pressed, a chain of events is set off. You can cancel it before it finishes dialling but otherwise the company wants to hear from you, and the one I saw was happy for the button to be pressed a few times a month to reassure everyone that the system worked.

 

My understanding of any emergency service callout is that it's irrevocable. You ask for a fire engine? They will come and check there is no fire, and if that was an abuse then you're in trouble.

 

If the use case is marina-wide then there seems to be a niche for devices to attempt to organise a local response before escalating to emergency services. So back to the question, what is a sensible thing to fill that niche? And @Yank on the Cut, is that the question you wanted raised?

 

AI powered devices are coming into existence for this niche. I presume they seek to cut out the human from the 'commercial subscription call centre' and make the decision to escalate to emergency service callout by applying a 'giant spreadsheet of carefully chosen numbers'. At least the emergency services have a central organisation to negotiate with if it does stupid things.

In a marina no one hears you scream - well, perhaps they don't if you are in the water and no one else is close by.  It needs to be simple, inexpensive and very portable. Ideally a small portable alarm to obtain help.

[wakey_wake]

12 minutes ago, Yank on the Cut said:

In a marina no one hears you scream - well, perhaps they don't if you are in the water and no one else is close by.  It needs to be simple, inexpensive and very portable. Ideally a small portable alarm to obtain help.

I agree, but we don't know of one that does this. Therefore I'm thinking of questions that lead to something like a design spec.

 

Does it make a louder noise than a person could? What should that sound like?

Does it send a radio signal? What is picking that up, and how far away? Then what does it do?

If the marina has nobody within 200m, who is it you hope will bring help?

 

Of course it depends how many seconds one has before not surfacing 🥶 which is unknown.

[Yank on the Cut]

7 minutes ago, wakey_wake said:

I agree, but we don't know of one that does this. Therefore I'm thinking of questions that lead to something like a design spec.

 

Does it make a louder noise than a person could? What should that sound like?

Does it send a radio signal? What is picking that up, and how far away? Then what does it do?

If the marina has nobody within 200m, who is it you hope will bring help?

 

Of course it depends how many seconds one has before not surfacing 🥶 which is unknown.

Typically, people fall in off pontoons/jetties or when they are stepping on or off their boats from the very same pontoons/jetties. In a typical marina, that means they will be able to grab hold of a pontoon/jetty or a fender/tiller/what have you on the boat. If the water is shallow and they feel up to it, they can stand and walk out assuming the bank is soft or use any ladders that are closeby and long enough to get a foot onto the bottom rung. But most people simply focus on hanging on. What resources do they have to raise help? Their voice. A fist to bang on the side of a nearby boat.  What about a slim aluminium whistle on a boat key ring?

[wakey_wake]

4 hours ago, Yank on the Cut said:

Typically, people fall in off pontoons/jetties or when [...]

But most people simply focus on hanging on. What resources do they have to raise help? Their voice. A fist to bang on the side of a nearby boat.

 

Seems there are categories,

1. Fall in, struggle a bit, then self-rescue. Ladders are helpful. Personal alarm only brings witnesses to point and laugh.
2. Fall in, manage to stay afloat, but need help to get out. Voice or whistle is available to request help, if that is effective.
3. Fall in, incapacitated by cold shock or head injury or broken limb. Voice may not work, whistle may be useless.
4. Fall from moving boat is a whole other bottle of sharks.

For me a personal alarm is most useful in incapacitation. Then it needs to work in seconds, unless you have an auto-inflate to gain some minutes.

 

I dunno. It seems like we've been here already and I haven't seen the Woozle yet.

 

4 hours ago, Yank on the Cut said:

What about a slim aluminium whistle on a boat key ring?

 

Slimmer and more robust than a plastic one. I would have it on a lanyard round my neck, because pockets could be difficult to reach; or worse if I've gone in while attempting to recover the keys I dropped in.

  

On 14/04/2026 at 18:24, LadyG said:

Blow the whistle attached to the life jacket.

😉

 

But I rarely carry a whistle. Maybe I should.

[Yank on the Cut]

I suspect unlikely that people will fall in trying to recover their keys. Lanyards are not popular. Whistles should be delivered today to attach to keyring. 

 

Practice makes perfect - the more times you fall in the more likely you will get yourself out all other things being equal. 

[Tigerr]

My lovely wife fell in at the marina, while we were loading the boat for cruise, a february night 10 years ago. It was a nasty lesson. She was carrying a box/bag in front of her. Tripped on the uneven deck/fittings, and pitched over the stern into the freezing water. Cold shock - she was unable to cry out, at all. She could only gasp. I only noticed when I emerged from the cabin a minute or so later - and saw the bag floating in my headlight - it took a moment to spot her gasping face just above the surface. No way at all could I lift her aboard, no ladder, etc. I ran to the marina office and very luckily there was a ladder, and we managed to use it.

It took her two days to physically recover, and an hour in the hot shower. 

I dont know of a practical device that would solve the issue. It is an inherent risk of water and boats. 

But we learned - you never carry stuff on in front. Ever. Take boarding seriously. Consciouly look where your feet are going. Manage boxes etc carefully, avoiding stepping aboard with loads. And, we bought one of those ladder/gangplanks, and rope ladders front and aft easily reached from down in the water. 

All that said, we've now moved off the cut, as one reaches an age where the locks become not just potential risks, but a disaster waiting to happen. 

I am now boating in the sea, and weirdly, it might be safer!

[wakey_wake]

8 hours ago, Yank on the Cut said:

Practice makes perfect - the more times you fall in the more likely you will get yourself out all other things being equal. 

 

Perverse as it may sound, there is something here. ☝️

 

The trend for ice plunge baths may be further than is needed, but once a body adapts to cold immersion it copes better with repeats for months after.

Therefore, a valid preparation for the "unintended fall into February navigation" may be "cold showers in preceding August". 🤔

[GUMPY]

I've been in more times from the Kayak than I ever did from proper boats in 50+ years.

However it's always in warmer weather 🫣

[wakey_wake]

2 minutes ago, GUMPY said:

I've been in more times from the Kayak than I ever did from proper boats in 50+ years.

However it's always in warmer weather 🫣

😁

I know kayaks have a capsize & righting drill? Never done that for a steel boat...

 

I was considering blowing ~£100 on an inflatable one (plus licencing of course), for the exercise.

Is that too cheap? I have desk-job arms so I may not go far.

[GUMPY]

20 minutes ago, wakey_wake said:

I know kayaks have a capsize & righting drill? Never done that for a steel boat...

Nothing to do with that, it's falling in whilst getting in and out. Kayak is an inflatable bought refurbished from the manufacturer, Aquaplanet, cost me £200 in 2024 and is more rugged than most. 

Edited April 22 by GUMPY