Man Overboard warning system

[bcervelo]

I believe there is a man overboard warning system on the RNLI Atlantic 85, does anybody know how this operates?

[Cookee]

Originally Posted by bcervelo

I believe there is a man overboard warning system on the RNLI Atlantic 85, does anybody know how this operates?

We used to have one in OCR if the crew were one behind the other - we just linked a kill switch up to a light - you can add a horn if required.

No idea how the RNLI do it but it's probably -

1. More complicated
2. A lot more expensive
3. incredibly robust

[bcervelo]

I was involved in an incident last weekend where a crew member broke his ankle in a foot strap after the boat went over a wave and he lost his balance, luckly we heard him scream and stopped sharpish.
He could have so easily gone overboard and we may not have noticed for a few minutes.

This got me thinking of installing some sort of system to warn the helmsmen of a man overboard.

My idea is also to have kill switches at crew seats and each crew member has a kill cord, i have done a quick sketch of what i think the wiring should look like, any advise.

[Cookee]

Originally Posted by bcervelo

I was involved in an incident last weekend where a crew member broke his ankle in a foot strap after the boat went over a wave and he lost his balance, luckly we heard him scream and stopped sharpish.
He could have so easily gone overboard and we may not have noticed for a few minutes.

This got me thinking of installing some sort of system to warn the helmsmen of a man overboard.

My idea is also to have kill switches at crew seats and each crew member has a kill cord, i have done a quick sketch of what i think the wiring should look like, any advise.

Get Yamaha kill switches as they're indestructible and bin the relay they will operate a light without one.

[bcervelo]

Originally Posted by Cookee

We used to have one in OCR if the crew were one behind the other - we just linked a kill switch up to a light - you can add a horn if required.

No idea how the RNLI do it but it's probably -

1. More complicated
2. A lot more expensive
3. incredibly robust

Looks like the RNLI use a kill switch setup as well, notice the lanyard fwd of the comms system.

[ShinyShoe]

Replace the light with a warning LED. Far less likely to blow.

Do you want the light on or off when the switch is pulled?

Would make sense to use the same KC as your helm what is that?

[mister p]

Have I missed something or is the kill switch not exactly what you want. Surely if helm is concentrating enough not to notice MOB, the last thing he /she wants under ( I assume ) extreme conditions is loss of control.
A warning yes, but loss of power? I don't think so. Very confusing and dangerous. Flooding from wake at the stern is just the beginning.
Big warning but not kill.

[paulbrown22]

These additional kill switches are just being used such that each crew member has something attached to the boat.

From what I see/understand, they won't cut the engine, they will just cause a warning light/horn/siren/whatever to activate when one of the additional kill cords is pulled.

[ShinyShoe]

Don't think they are wired into the engine ignition like a normal KC - just using the same switch "technology"...

[chris123]

The Atlantic 85 has an additional kill cord at the 4th (back) seat only, wired to a warning light at the helm seat and a loud buzzer. There is no connection from this kill cord to the engines.

Pull the cord, and the light comes on and the buzzer sounds. There is also a mute button to shut the buzzer up so you can hear what you are doing whilst you pick the MOB up.

When the A85 gets its new nav system, pulling the cord will also put an MOB alert on the chart system

Cheers

Chris

[ribrunt]

Wot Chris123 said...Think also present on ALBs for helm if alone at USP...

[bcervelo]

Originally Posted by mister p

Have I missed something or is the kill switch not exactly what you want. Surely if helm is concentrating enough not to notice MOB, the last thing he /she wants under ( I assume ) extreme conditions is loss of control.
A warning yes, but loss of power? I don't think so. Very confusing and dangerous. Flooding from wake at the stern is just the beginning.
Big warning but not kill.

As said i will use the kill switch to activate a buzzer and/or warning light, not to cut power to the engines.

[bcervelo]

Originally Posted by chris123

The Atlantic 85 has an additional kill cord at the 4th (back) seat only, wired to a warning light at the helm seat and a loud buzzer. There is no connection from this kill cord to the engines.

Pull the cord, and the light comes on and the buzzer sounds. There is also a mute button to shut the buzzer up so you can hear what you are doing whilst you pick the MOB up.

When the A85 gets its new nav system, pulling the cord will also put an MOB alert on the chart system

Cheers

Chris

Chris, any idea how that link to the MOB alert on the plotter works?

[ShinyShoe]

I'm guessing they feed something in via NMEA?

NMEA 183 would let you have a bit of kit that captured the current pos and fed it back as a WPT named MOB? Possible to also send it on NMEA as though it was an AIS Meesage 14?? Would probably take a fair bit of fiddling. Hassle for 1 RIB but bear in mind the RNLI have hundreds with the same kit, plus I'm sure they have enough power to go to Garmin or whoever they buy their plotters from and say can you tell use the best NMEA sentence to do this...

Not sure what's needed to do that - if you need to get the possition and build it into the sentence to send back that sounds rather complex. If you could send the NMEA without the pos and the recipient system would know that meant current pos then it may be pos with some simple chips?

NMEA 2000 is probably far more appropriate than 183. Not going to be a £20 solution...

[Poly]

Our sister forum (MOB NMEA sentence - Cruisers & Sailing Forums) has some discussion on this. Several of the fancy electronic MOB systems will output NMEA messages if they detect someone has gone for a swim.

[willk]

Originally Posted by Poly

Our sister forum...

er, they appear to be WAFIs P. Not sure they can be immediate "fambily" - second cousins maybe. On our mother's side.

[9D280]

Originally Posted by bcervelo

Chris, any idea how that link to the MOB alert on the plotter works?

I would guess it's a bit like a remote switch version of the ones most plotters I've seen have - push the "MOB" button & it drops a "mob waypoint" on screen with an "auto goto" to provide a big arrow to point you at them.

[chris123]

Originally Posted by 9D280

I would guess it's a bit like a remote switch version of the ones most plotters I've seen have - push the "MOB" button & it drops a "mob waypoint" on screen with an "auto goto" to provide a big arrow to point you at them.

That's pretty much it - the plotter has a switch input with the MOB button / MOB killcord at the 4th seat wired in series across it. Press the button on the console or pull the MOB killcord and the circuit breaks.

The plotter records the MOB position as current GPS position, and displays an MOB mark on the chart at the location. It also gives range and bearing back to the MOB, as well as time to get back to MOB at current speed and time the MOB has been in the water.

Cheers

Chris

[C2 RIBS]

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