Recent comments on my "kick-off" post about upcoming Navagear coverage of man-overboard (MOB) alarm systems got me thinking: Maybe I should reconsider Raymarine’s LifeTag system.
If only I could get it to kill the engine. See, stopping the boat is my primary goal in an MOB situation aboard Two Lucky Fish, a C-Dory 22 that I often operate with young children as my only crew. Obviously, an MOB waypoint would be nice, but it’s a secondary consideration.
So I decided I better read the LifeTag System Installation and Commissioning Guide. Lo and behold…LifeTag includes a 12V output that can be used to trigger "appropriate emergency systems."
Raymarine doesn’t suggest what those might be, but I got one:
Hows about a relay that, when energized, will close the "engine kill" switch on my outboard? Et voila, instant engine kill functionality!
Wire the LifeTag output to a simple dash-mounted toggle, and I could override the engine kill, start ‘er up, and head back toward the MOB. Assuming the MOB ain’t me, of course.
So now I’m thinking…maybe I’ll get LifeTag, after all. The simple plug-n-play installation is extremely attractive. It’s price-competitive with the MariTech Virtual Lifeline, my current (but as-yet unpurchased) MOB alarm of choice.
Well, it seemed like a good idea, but…um…no. While describing the system’s operation, Ben over at Panbo wrote "After a 10 second delay, the buzzers go off and the …"
SAY WHAT?!? "Ten second delay"? Furreal?!
Apparently. According to the LifeTag System Operating Guide, "A built-in 10 second delay is included, between the initial signal loss and the alarm sounding, to minimise [sic] the likelihood of false alarms occurring."
This really is NOT OK with me. At 20 knots, my boat will keep running for about 337 feet before the engine-kill relay is triggered. That’s a LONG swim.
At 12 knots, a more conservative speed in any sort of wind and chop, the boat would still be 200 feet away. In any significant breeze, the boat will end up being blown to leeward, perhaps faster than I can close the distance.
This ten-second delay is a deal-killer for me.
I need the engine to stop as soon as possible. The MariTech people assure me that their system actuates immediately, and their videos certainly appear to confirm this. Saltwater may inhibit the worn transmitter’s broadcast strength until the MOB pops back up, so an additional second or two may elapse before activation.
Rest assured we’ll be testing this once we get the system aboard. But the moral of today’s story is "Make sure you really, REALLY understand how these systems work before you choose one."
A secondary conclusion: Raymarine is to be applauded for making all their manuals available online. This is tremendously helpful in many situations, and greatly appreciated.
{ 8 comments… read them below or add one }
I’ve just confirmed that the Mobi-Lert unit also imposes a 10-second delay on its built-in triggered relay. This despite the fact that Mobi-Lert activates “instantly” when the signal from a transmitter is lost.
The delay is imposed, I suppose, because of the chance of false alarms with so-called “active” or “proximity” systems like Mobi-Lert and LifeTag. See the manual here.
Hey Tim,
This is a really interesting project, which reminded me of a new product called Autotether that you might want to look at.
http://tinyurl.com/yurqt6
Tim,
If you are operating at 12 to 20 knots, why would you be away from the helm of your C-Dory, to be able to fall off the boat? Especially if your crew is your kids, wouldn’t you be seated or standing inside the cabin, beside the helm?
I can see the posibility of being thrown across the cabin, and having the boat go out of control. in that event the clip on kill switch lanyard should stop the boat.
Training your kids to pull the stop switch lanyard in the event you are disabled or overboard is another posibility.
Larry H
Oh, I might be pulling in the fenders or coiling up docklines or something. Once free and clear, it’s no trouble to set the autopilot and tidy up the cockpit area, peaking forward every few seconds to watch for logs. Honestly, the chance of falling overboard from my boat is extremely low.
It’s just that if it did happen…well, it could be a disaster, or it could be a funny anecdote you tell your buddies over beer. That, plus I’m interested in the various ways of dealing with MOB risk on different kinds of boats, and I’m a gadget junkie.
Tim,
Ah, the dangers of autopilots!! I also have pulled fenders and dock lines while leaving harbor, but I had the wife steer the boat while I was doing the chores.
My humble suggestion would be to get to a safe area away from the dock, put the boat in neutral, and then go into the cockpit to do the chores. I would never trust the autopilot and leave the helm, unless there was someone else to steer or at least monitor the course. If an electronic glitch or a mechanical failure were to put the helm hard over, that could throw you out of the boat. I would also never put much trust in an electronic shut off device. It would be dificult to test such a device each time you leave the dock for proper operation.
Regards,
Larry H
I don’t see a real difference between 10 feet and 50 feet if the boat is still moving in the wind. Either you make it or you don’t. The real trick would be to deploy the sea anchor when someone goes overboard!
It sounds like you’re talking about a sailboat, Jeff.
The solutions I’m investigating, for my particular situation, would in most cases be utterly ridiculous for a vessel that spent any time at all under sail. That’s why I keep harping on this: PLEASE take the time to learn about and UNDERSTAND the MOB systems available before you purchase and install one.
the point of having the boat shut down when the operator falls overboard is equally important for the safety of the passengers onboard, ie kids, sleeping adults, unqualified operators, etc.
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