MacGregorSailors.com

Clearly, a GDO is not the ideal solution.

I wasn't thinking of making it fail-safe.

Rather, I was thinking of a manually activated remote control that you hit while you're in the water. Simply, the garage door opener that comes with it, but sealed in a zip-lock bag. Yeah, this requires that you go overboard conscious and able to get to the button... But, if you're sailing solo and unconscious or incapacitated, you likely couldn't get back aboard anyway... Yeah, yeah, I'd still rather have my boat hanging around, even if I couldn't get back aboard...

You could also have a big red button somewhere that non-sailing/non-boating passengers could hit, if you went over. Of course, who know what kind of ride they'd be in for when the steering just goes all the way to one of the stops...

No, this is probably not even a good solution. But, with a little thought, trial and error, you probably COULD make it work, at least work better than nothing...

Although, one of the things we're assuming is that cutting electrical power to the engine will shut it down. I don't think that's the case, at least for my ETEC. Evinrude claims that you can start it without a battery at all... So, then just cutting power probably won't get it done...

And with that, we come back to that silly little ignition lanyard...

According to the web page of the device, "Once submerged, the sensor transmits a signal to the control module, which sounds an alarm and immediately shuts off the motor..." That makes it like my GDO, which only responds when a pulse is transmitted, and battery life becomes less of an issue.

But how does the unit transmit a signal to the receiver when/if it is under water?

Chip Hindes wrote:Maybe you should be happy they're not listed at $1500.

Course if you want to spend more you can- How about (only) $1595.00?

http://store.yahoo.com/landfallnav/-s1000w.html

This was listed in a Landfall Navigation catalog I just received.

Greg

Angel Alert or Safety Turtle

The above devices could possibly be used in conjunction with a audible sensor circuit that opens a relay when triggered. Open relay would shut down the motor- push button to override.
Greg

Guess I should have read the marketing blurb before I commented. The ability of the control unit to accept signals form more than one transmitter would prevent it from working in the failsafe mode I described. Otherwise it wouldn't go off unless it lost signals from all four transmitters. Obviously that's no good. For failsafe as I proposed it, I suppose each of the transmitters could be uniquely coded just like you can change the code on your GDO. But at this point I've pretty much exhausted the depth of my electronics knowledge and I dont know if this is a reasonable thing to propose.

So this one at least, doesn't fail safe. I see there is a "sensor test" label on the control unit which is not described in the blurb. That would partially compensate for non-failsafe operation if you remember to regularly test the sensor. The range is stated as 150 line of sight which is kind of a useless specification. It would be interesting to know how far that translates underwater.

Theres little doubt it works by cutting the ignition just like shutting it off with the key. With a powerboat thats a no brainer, especially when shutting the engine down and thereby locking the prop is functionally equivalent to slamming on the brakes, making it fairly likely that if youre still conscious, you can at least make it to the vicinity of the boat. Climbing back aboard without assistance is a whole nother discussion.

On a boat under sail, its not quite so simple. Though Im not an electrical guy, it would seem relatively easy to wire some additional functionality into the ignition cutoff circuit to trigger some other event(s) on activation of the control signal. However, what event(s)? I can think of no single action which will work equally well, or even acceptably, under more than a few of the many combinations of wind, current, and point of sail.

So, the problem is in two parts:

First, what exactly do you want the boat to do?

Second, how and with what electromechancial devices do you direct the boat to execute the event(s) to accomplish what you decided in (1) above?

IN the marketing world, "transmitting a signal" is equivalent to "interrupting a signal" so I dont think the blurb is evidence that this product doesnt fail safe...individual sensors could be coded with RFID technology at the price point they are selling it

..of course unlike Chip who graciously states he has reached his EE limits, I exceeded mine three posts back...

Chip Hindes wrote: . . . First, what exactly do you want the boat to do?

Second, how and with what electromechancial devices do you direct the boat to execute the event(s) to accomplish what you decided in (1) above?

Seems to me that moving the rudders to either lock and holding them there ...
would stop it's sailing (at least "interrupt" it's sailing) regardless of the point sailed?

Seems to me that moving the rudders to either lock and holding them there ...
would stop it's sailing (at least "interrupt" it's sailing) regardless of the point sailed?

Not necessarily. If moving to one of the locks induced an unintentional mainsail gybe (pretty much a 50 % chance if the direction is random) it could take several hundred yards to complete the operation; in high winds you might even get a knockdown. Even if it eventually went into a hove to condition, in decent winds you can still get 2.5-3 knots downwind speed; way faster than you can swim.