£3 MOB alarm

[sam_uk]

I have a Android phone and spotted a app called 'bluetooth umbilical'

The app sounds a alarm on the phone when a blue tooth device goes out of range. (5-10 metres)

It occurred to me that this could be used to make a budget MOB alarm. The phone is plugged in in the cabin and connected to your speaker system.

Each crew member is issued with a charged £3 bluetooth headset http://bit.ly/Jn2IUd at the start of their watch to keep in a inside pocket. In the event of a MOB the alarm would sound and rouse any off-watch crew to assist.

Equally if the battery goes flat the alarm sounds to alert everyone. The rechargeable batteries are advertised to work for about 70 hours.

You could even go wild and spend £20 on a decent bluetooth headset, in which case you might want to keep it in a waterproof container like this http://bit.ly/ISUdEH

The app can even call someone when the alarm sounds, which might be of interest to those that single hand in coastal waters. A partner could be briefed to return any call and raise the alarm if not answered.

It's not as good as a lifetag or whatever but it is within my budget!

 

[WilliamUK]

One potential issue... and this isn't something I've looked into so disregard if you know I'm mistaken... is it possible to connect more than one bluetooth headset to a single phone? If not, that could be a potential downfall to what otherwise seems like a rather clever use of the technology.

I'd want to do some pretty extensive dry-run tests (and then some controlled tests, like chucking one overboard in an aquapac tied to a MOB buoy) before I even thought about using it when lives are at stake, but if it works... well... score one for the budget approach.


You'd want to be pretty sure that dunking the headset in the water wouldn't prevent the alarm working, and that the app checks for proximity of the headsets on a regular enough basis (if it only checks once every 5 minutes and someone falls overboard immediately after it checks they are there a full 5 minutes in the water would elapse before the crew were alerted to the problem).

 

[sam_uk]

I'm pretty sure you can connect more than one bluetooth device to a phone, but I have not tried it either.

The alarm sounds whenever the phone loses connection so it should sound on distance, flat battery or dunking alike.

On the basis of using this I would not take any additional risks. I would view it as A system that 'might' work.

I'm not choosing between this and a lifetag because I can't afford a lifetag at the moment. I'm choosing between this that 'might' work or no system at all.

 

[WilliamUK]

Makes sense - I'd still be doing dry-runs to find out though. Something that might work might cause a little complacency even with the best intentions. If I tested it and it turned out somewhat useful you'd know and if not you'd know not to even bother with it.

 

[photodog]

Ha!

I had that idea last year!


I think we need a purpose built app that would allow you to see all the bluetooth devices registered...

Then, in conjunction with the gps in the device, would sound a alarm if one went off line.. And give a bearing and distance tothe point were it went off line...

When you got back into bluetooth range of the lost device... It would also sound a alarm...

You could even have the app send a text or something to alert someone back home...

Lots of choices of bluetooth devices.. Including waterproof watchs.. That could be paired up...

 

[sam_uk]

Some good ideas there photodog..

Probably not all that hard to put together. The 'return to GPS location' stuff already exists in the various car-finder applications.

I found a app that can alarm when a bluetooth device comes _into_ range, so that is certainly possible. Not sure how useful it would be. If you are only 10 meters away from a MOB you can probably see them anyway.

The phone call home stuff is already built into the 'bluetooth umbilical' app I mentioned in my first post.

 

[onesea]

Ha!

I had that idea last year!

I think we need a purpose built app that would allow you to see all the bluetooth devices registered...

Then, in conjunction with the gps in the device, would sound a alarm if one went off line.. And give a bearing and distance tothe point were it went off line...

When you got back into bluetooth range of the lost device... It would also sound a alarm...

You could even have the app send a text or something to alert someone back home...

Lots of choices of bluetooth devices.. Including waterproof watchs.. That could be paired up...

If like most of us your crew normally have a phone, maybe a freebee (or very cheap) app to be receiver station and a pay (or slightly more expensive) app to be the base.

Then any one with a phone in there pocket can be on the system. Using blue tooth, Wifi or GSM to transmit back to base their position in the worst case event... As for water proofing a zip lock bag?

As you say other devices would be good, but using a phone would be good even better if it can be non smart phone.

Particularly if apps are eventually cross operating system Java? Android, Symbian, Windows and not missing I.

 

[rogerthebodger]

It would also be nice if there was an application that would allow several bluetooth headset's to communicate with each other i.e. between crew members one at helm and crew on foredeck.

 

[newWave]

I just did a test on a Linux laptop with the following results :
- Scanning for devices takes about 10 seconds, so at 25 knots this puts you at 128.6 meters after detecting a lost device/MOB. Provided of course that all devices used to perform the detection have a similar interval. Obviously you need to add the range of the device for the total distance.
- Every device has a unique address, so it doesn't matter what type of device it is (cell phone, computer, tablet, headset) as long as it is transmitting within range and has sufficient range.
- Range of a device depends on the type : Type 1 = 100m, type 2 = 10m and type 3 = 5m.

The simplest of programs would read data from a known devices file and alert when a device goes out of range.
A second program can be used to detect new devices and create a list, which can then be added to the known devices file.

A more complex program would offer a user interface to get all that done, but you get the drift.

Just need to find an iPhone and an Android device together with the APP instructions and then it should be a doddle to create.

 

[JackFrobisher]

Wow!

It would also be nice if there was an application that would allow several bluetooth headset's to communicate with each other i.e. between crew members one at helm and crew on foredeck.

An iPhone/Android 'phone acting as a base station for two or three bluetooth headsets. An inexpensive and private and hand's-free intercom for the crew. Now there's a really good idea for an App! I have no idea how it might be done but I'd buy it.

 

[rascacio]

An iPhone/Android 'phone acting as a base station for two or three bluetooth headsets. An inexpensive and private and hand's-free intercom for the crew. Now there's a really good idea for an App! I have no idea how it might be done but I'd buy it.

Yes I agree. I've been looking in the past for a bluetooth 'Hub' so everyone could stay connected. Would be well handy up the mast or anchoring when it's windy. Walkie talkies are a pain in the arse when you need two hands.

Alas I've not found one yet. Anyone else found anything ?

 

[Baggywrinkle]

It could be done with any bluetooth profile which allows multiple connections. PAN (Personal Area Network) for example. (Any PAN capable device could act as a personal beacon)

Once the devices are paired with the 'base station' then the app could take over.

It could ping each device (check it is still on the network) every second and sound an alarm and record the GPS co-ordinates of the base station when a device failed to respond.

The app could also show heading and distance to the MOB POI, and re-detect the MOB when it came back in range (assuming it was waterproof and still responding) sounding a second proximity alarm.

If networked to the boats instruments/plotter it could be even more useful ...

all relatively straightforward, more bells and whistles could be added once the basics were working.

Or an adaption of something like this .....

http://9to5mac.com/2011/10/12/find-my-friends-app-goes-live-ahead-of-ios-5-release/

... but it requires an internet connection.