MacGregorSailors.com

Some time ago we had quite a thread regarding jacklines, tethers, trailing lines, motor kill switches, etc.

I, for one, wished for a wireless device that would kill the motor if I fell overboard while singlehanding.

WELL, HERE IT IS.

http://www.powerboatsafety.com/

BoatU.S. Magazine March 2006 page 49 has an article entitled "Mob Me" which explains that if you have one of these $469 devices, wear the wireless lanyard and go in the water, it will stop your engine. Now, how do we get it to lower the sails?

Jack O'Brien wrote: Now, how do we get it to lower the sails?

Nice find, Jack.
I guess we'd need a shackle that's held closed by electricity. When this VL thing chops the power to the motor it also kills the power feed for this "magic shackle." Of course, this shackle is the bottom link for the mainsheet tackle - and cutting its power causes the magic shackle to release the mainsheet!

Ever seen an electric shackle ???

Ouch! I think I got a little frostbite when the price hit me. I hope it comes down eventually. If you were offshore , I don't see how you could afford to be without it. Nice find Jack.

Might be nice to have the same signal tell an autopilot to put a boat undersail in irons, or set off the epirb, or even trigger an alarm down below so sleeping crew would be aware.

Hmm.. pretty interesting. I'm a bit concerned that it only transmits 150 feet, line of sight, though... if the boat is *really* moving, and somehow the sensor doesn't get wet right away (in a pocket or something) the boat could be long gone and the system would fail.

Now, if you're worried about falling over and wanting to kill the motor if you do, then as a prudent boater you *should* be cliped to the kill-line on the ignition.. i't low-tech, but it *definitely* stops the motor. And only costs about $4.00, too!

kmclemore wrote:
Now, if you're worried about falling over and wanting to kill the motor if you do, then as a prudent boater you *should* be cliped to the kill-line on the ignition.. i't low-tech, but it *definitely* stops the motor. And only costs about $4.00, too!

True, but most don't use them because of their short leashes, nor would a lanyard cover small children like Dmitri's new brood, nor pets.

That price should tumble as this is consumer RFID type technology - unless they have the IP locked away tight...you could imagine everyone being issued a RF tag (like the ones the Exxon Mobil give you) and if anyone gets more than 15 feet from the main controller it would sound an alarm or stop the motor...

We still need to protect ourselves when we are sailing single or short handed, motor not involved. Tethering ourselves to a jack line so we are not overboard in the first place seems best until the technology catches up to the older, better form of locomotion... sail. Yet, jack lines are very rare in most marinas.

With 4 sensors if a passenger wearing one falls over and the motor is killed, is there an over-ride so you can motor back to MOB??

(Gulp) ..one would hope....

I would think you could operate this in a mode where it would kill the engine for singlehanding, or sound an alarm for full crew - especially at that price point..

It looks like garage door opener technology to me: a remote transmitter and a receiver that opens a circuit, instead of closing one. Waterproof, of course, except for the remote sensor. But the price, compared to a garage door opening system, is over the top. Sears best garage door opening system is only $289.00 and includes 2 remotes, a hp motor and a belt system for raising and lowering the door.

Garage door openers also have circuits to turn on a light, which could be rewired to kill the motor...

Heck, you could even configure the lift motor to cut the wheel hard over in either direction, just like a jetski!

Drop a remote into a ziplock baggy and it's as waterproof as need be...

The only problem is that they require AC, which means a generator or an inverter running all the while... Check that, I remember seeing a commercial for a unit that would work after the power went out. So, it must use some DC somewhere... Maybe it has its own inverter...

"BLT" Says

Heck, you could even configure the lift motor to cut the wheel hard over in either direction, just like a jetski!

Yeah, Fall over, Get your bearings, Surface just in time for your boat to run you over!!

On Edit, Just kidding, Dont hurt me, I bruise easy! Heehee!!

I hadn't thought about your boat running you over, but I wasn't really suggesting that anyone try it either... I know I won't be trying it any time soon.

Rather, I was just noting that it seems possible...

The more I think about it, though, the more it really does seem doable with very little modification to the garage door unit... You could probably even wire in a switch to control which way you wanted it to turn...

It seems kinda redneck, even for me, but it should be possible...

Garage door opener (GDO) control circuits are low voltage, and pretty sure they're 12VDC. That's why the auxilary opener buttons can be wired with itty bitty single pair 24 or 28 gauge wiring, no ground.

They are not necessarily low power consumption, however, since with a 120VAC inverter the supply side at the opener may as well be limitless. A GDO on standby runs normally open, consuming minimum power until the contacts are closed by the momentary signal from the remote. Battery life of the transmitter is not an issue, because a nearly instantaneous pulse is all that's required to energize the opener.

On the other hand, failsafe mode on a wirelss MOB cuttoff would require that a power or signal loss be treated the same as an actual MOB event. The transmitter signal must broadcast constantly. The switch at the business end must be normally open, but held closed electronically in response to the transmitter signal, to maintain normal operation. Then, in the event of either a specific command or simply, loss of transmitter signal or power, the switch would open. Both of these would consume additional power compared to the GDO. Battery life of the wireless device would be an issue.

A frequent occurance with my GDO is that it doesn't work the first time pushed. Push it again, remove it from its carrier, aim it better, bang it to reseat the battery and restore power, it eventually gets through and opens the door; or doesn't because there's actually a problem or the battery's dead. Then you pull the string and open it by hand. Inconvenient, time to get it fixed but hardly life threatening. Not too acceptable with a MOB cutoff.

Or conversely, picture yourself in a restricted maneuver area with maybe some wind and current, trying to motor out of the way of a supertanker, and have your MOB switch decide (erroneously of course) you've gone overboard and cut the motor on you.

You know you're haveing a bad day when...

Maybe you should be happy they're not listed at $1500. Just kidding but you should get the point. A GDO isn't nearly as critical an application as a MOB cutoff.

Reminds me of the joke:

"How much is it?"

"Fifteen dollars."

"That's too much, the guy down the street sells them for ten."

"Then why don't you buy it from him?"

"He's out of stock."

"When it's out of stock here I only charge eight."

Ba dump bump.

I'll be glad to sell you a wireless MOB device that doesn't work for only slightly more than the price of a garage door opener.