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Old 21-03-2014, 01:45   #121
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Re: Man Overboard with Auto Pilot Engaged!

last year, Yachting Monthly did a test with a dummy (no not a real person) thrown over the side wearing a PFD and on a tether. The tether was long enough that the dummy was dragged though the water.

The test showed that if your tether is this long you will drown. The combination of the PFD and tether, had the dummy facedown and at 5-6 knots, water would have been rammed down the dummy's throat (had it been a real person).

The same will be true if you grab a trailing line (you'll end up face down and water will be rammed down your throat).

As for the idea of pulling yourself 20-30 meters up a rope while being dragged through the water at say 6 knots - there are perhaps some who can (life-threatening danger does strange things to peoples capabilities), however most simply cannot. Especially if they are getting mouthfulls of water and there are large waves etc.

The only solution that might work here is a tripline that effectively stops the boat. Such a thing can be rigged on virtually any boat if enough ingenuitiy is applied. Having this line firmly attached to your harness then completes the circle.

I have to wonder though - why go to all that trouble? isn't it enough to just tether yourself in at all times? The "fall out of the boat tripline" seems like a lot of work for an extra safety precaution. A liberal sprinkling of places to tether and a good tether would seem to be adequate.

For those that like to wear both a belt and suspenders - just make a habit of having two tethers at all times
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Old 21-03-2014, 09:13   #122
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Re: Man Overboard with Auto Pilot Engaged!

Any MOB alarm that sounds an audible alarm can be wired to a relay that then can be used to shut down a engine or maybe even turn a sailboat into the wind, but not sure how to wire that into a autopilot.

Raymarine LifeTag
Man overboard alarm, integrated with Ray Marine chart plotter
Raymarine LifeTag Man Overboard System

Holt Mobwatcher
Engine Kill system for MOB
Boating Business - Wireless MOB engine kill system

Mobilarm MOBi-lert 720i, now obsolete, replaced by:
mrt Crewguard monitors 121.5 MHZ for MOB signal from device on crew
MRT Crewguard - Product Information - Marine Rescue Technologies

MOB Guardian
No longer available
MOB Guardian

Nasa Marine MOBi
Crew overboard detection, the base station sequentially interrogates each transponder which then broadcasts its presence. In the event of a crewmember falling overboard the drop in signal level is detected by the base unit, which sounds a high intensity audible alarm. From England
Misc: NASA Marine Instruments

Cerberus
Not really a MOB device. Uses your iPhone, iPod touch, or Android to send and receive email from anywhere by satellite
https://cerberus.briartek.com/cerberlink/plans
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Old 21-03-2014, 13:10   #123
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Re: Man Overboard with Auto Pilot Engaged!

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Originally Posted by westwinds View Post
Any MOB alarm that sounds an audible alarm can be wired to a relay that then can be used to shut down a engine or maybe even turn a sailboat into the wind, but not sure how to wire that into a autopilot.
Sounds like a good idea to me.

I would personally also fit a very reliable isolation switch, and try to remember to use it to disable the relay whenever it was not required, so that the relay would not accidentally shut the engine down at a crucial moment.

One (not very elegant) way to deal with the autopilot would be to have the relay divert power from the pilot to a linear actuator mechanically in series with the link to the tiller arm.

More elegantly (in the case of a pilot USING a linear actuator or hydraulic cylinder) simple put the diverted power on one side of the actuator, or the solenoid of the hydraulic valve.

The question of which side to divert the helm could be decided by a simple (damped) pendulum actuated switch, (which if you have a reasonably well-damped cooker, could simply be a roller microswitch 'reading' a cam on the pivot axle) which would tell the circuit which way the boat was heeling at the moment the signal to heave to was received. The relay logic would need to "latch" that piece of information so that subsequent signal reversals did not create havoc in the steering arrangements.
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Old 21-03-2014, 14:58   #124
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Re: Man Overboard with Auto Pilot Engaged!

Wouldn't it be enough to just slam the helm, hard over?
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Old 21-03-2014, 15:27   #125
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Re: Man Overboard with Auto Pilot Engaged!

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Wouldn't it be enough to just slam the helm, hard over?
That was kind of what I had in mind, yes.
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Old 25-03-2014, 09:57   #126
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Re: Man Overboard with Auto Pilot Engaged!

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Originally Posted by carstenb View Post
last year, Yachting Monthly did a test with a dummy (no not a real person) thrown over the side wearing a PFD and on a tether. The tether was long enough that the dummy was dragged though the water.

The test showed that if your tether is this long you will drown. The combination of the PFD and tether, had the dummy facedown and at 5-6 knots, water would have been rammed down the dummy's throat (had it been a real person).

The same will be true if you grab a trailing line (you'll end up face down and water will be rammed down your throat).


Logical fallacy. Some one failed so you will fail too.



"The same will be true if you grab a trailing line (you'll end up face down and water will be rammed down your throat)."

I will take "Things that didn't have to happen for 100.00 Alex..."
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Old 29-04-2015, 15:08   #127
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Re: Man Overboard with Auto Pilot Engaged!

To those that said you couldn't even hold onto a line im the water with the boat doing 6 knots - I don't know about how it'd work in very rough seas, but a game that we have played in fresh water lakes or in the Sea of Cortez is we tied a about 200' of polypropaline line, with "figure eight" know tied about every 3' or so to a stern cleat. A fender or float cushin was at the end. Then we'd take turns diving off the bow. Then swim and catch the line and pull ourselves back to the boat. We may only have been doing 5 knots, not 6, and the boat lost about a half knot as soon as one of the adults were dragging. We did not get pulled face down. And only the sub teen kids were wearing life jackets. It was FUN! But the water was flat.
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Old 04-11-2015, 09:03   #128
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Re: Man Overboard with Auto Pilot Engaged!

I will be doing a lot of single handed sailing so i bought a Raymarine Lifetag system for me and the dogs - this has an optional 12v output when triggered which i am using to trigger an engine stop solenoid and 3 relays - 2 on the motor feed wires and 1 on the clutch wires from the autopilot - they are 5 pin relays and the normal feed from the autopilot runs through the 'normally closed' side of the relays - this means that when the system is triggered, it disconnects the autopilots feed to the motor and clutch and is replaced with my own feeds (my own feeds are permanently live so it will work even if everything else is powered down) its actually a very simple circuit once you have a 12v trigger to work with.
I am also rigging up a microswitch on the rudder at full travel to disengage the power when it reaches the stop (if the rudder is forced off of the stop the switch will automatically re-instate the power to turn it back to the stop) because lets face it, after the trauma of falling of the boat and having to swim back to catch it, it would be a bit of a downer if the autopilot was on fire!
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Old 04-11-2015, 09:22   #129
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Re: Man Overboard with Auto Pilot Engaged!

If you're holding onto your trailing line and bring dragged behind the boat, you don't have to pull yourself hand-over-hand back to the boat. Use your legs, too, like this: bending at the waist and knees, pull your feet up as far as you can. Wrap one foot around the line so that you can clamp it against your ankle with the other foot. Straighten your legs while pulling with your arms. Get a new grip (closer to the boat) with your hands. Repeat. Not saying it would be easy. You can try this out by climbing up any line hanging from overhead, such as a halyard, or rope at a gym or tree.
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Old 04-11-2015, 15:58   #130
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Re: Man Overboard with Auto Pilot Engaged!

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Originally Posted by Steve Bean View Post
If you're holding onto your trailing line and bring dragged behind the boat, you don't have to pull yourself hand-over-hand back to the boat. Use your legs, too, like this: bending at the waist and knees, pull your feet up as far as you can. Wrap one foot around the line so that you can clamp it against your ankle with the other foot. Straighten your legs while pulling with your arms. Get a new grip (closer to the boat) with your hands. Repeat. Not saying it would be easy. You can try this out by climbing up any line hanging from overhead, such as a halyard, or rope at a gym or tree.
Hopefully you can already do 8-10 pullups. If not, good luck with that. Better to have a short tether.

I can do the pullups but wouldn't want to try and come back to the boat on a trailing line if the wind was up.

There was a guy in the SHTP (singlehanded race from San Francisco to Hawaii) that hand a loop line at the stern of his boat he could step in to get back aboard. He also used a short tether.
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Old 04-11-2015, 18:54   #131
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Re: Man Overboard with Auto Pilot Engaged!

never mind
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Old 08-11-2015, 04:43   #132
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Re: Man Overboard with Auto Pilot Engaged!

Speaking as sombody whe HAS done mob drills in the Atlantic, been the one in the water. You better hope that horseshoe is well polished and firmly inserted if you think any of these options give you more that a slightly better chance of surviving a solo MOB.
Unless you are tethered to you boat who cares if it rounds into the wind, try swimming after your drifting boat on a relatively calm day, moves faster than you can swim doesn't it! Now add waves and more wind - like the conditions that would make you go overboard......
Rope off the back of the boat, assuming you can catch it and haul yourself up to the boat under the conditions that caused you to go overboard maybe, but not many people go overboard in good conditions, once again try swimming in waves and finding the rope in time.....
Go overboard solo offshore and you are probably dead no matter what you think you have that will save you, a few people beat the odds but the majority don't. Enough stories about people on crewed boats not making it out of the water again, be simple if people went overboard only on nice summy days with 5 knots wind and near flat seas at noon on a warm sunny day, fact is it is usually the exact opposite conditions.
You want to live? Stay on the boat!
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Old 08-11-2015, 06:03   #133
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Re: Man Overboard with Auto Pilot Engaged!

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Originally Posted by secrabtree View Post
To those that said you couldn't even hold onto a line im the water with the boat doing 6 knots - I don't know about how it'd work in very rough seas, but a game that we have played in fresh water lakes or in the Sea of Cortez is we tied a about 200' of polypropaline line, with "figure eight" know tied about every 3' or so to a stern cleat. A fender or float cushin was at the end. Then we'd take turns diving off the bow. Then swim and catch the line and pull ourselves back to the boat. We may only have been doing 5 knots, not 6, and the boat lost about a half knot as soon as one of the adults were dragging. We did not get pulled face down. And only the sub teen kids were wearing life jackets. It was FUN! But the water was flat.
We do this too. My kids are early teens. Their only request...go faster! Also, dragging them really slows the boat, and turns the boat too, depending on where the line is made down.

Back to the main topic... Your tether is supposed to be short enough that you can never fall overboard. Clip to weather...you aren't going to fall UP. In the cockpit, a central clip point which won't allow me to leave the cockpit. When its rough...no one leaves the cockpit as a rule.

Forget the electronic gismos that cost $$ and will eventually fail when needed most, and just use some common sense.
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Old 08-11-2015, 06:07   #134
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Re: Man Overboard with Auto Pilot Engaged!

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Originally Posted by Siberianhusky View Post
Speaking as sombody whe HAS done mob drills in the Atlantic, been the one in the water. You better hope that horseshoe is well polished and firmly inserted if you think any of these options give you more that a slightly better chance of surviving a solo MOB.
Unless you are tethered to you boat who cares if it rounds into the wind, try swimming after your drifting boat on a relatively calm day, moves faster than you can swim doesn't it! Now add waves and more wind - like the conditions that would make you go overboard......
Rope off the back of the boat, assuming you can catch it and haul yourself up to the boat under the conditions that caused you to go overboard maybe, but not many people go overboard in good conditions, once again try swimming in waves and finding the rope in time.....
Go overboard solo offshore and you are probably dead no matter what you think you have that will save you, a few people beat the odds but the majority don't. Enough stories about people on crewed boats not making it out of the water again, be simple if people went overboard only on nice summy days with 5 knots wind and near flat seas at noon on a warm sunny day, fact is it is usually the exact opposite conditions.
You want to live? Stay on the boat!
Totally agree.

When I crossed the atlantic, I reminded myself often of the brutal reality...the other side of the lifeline, just a couple feet away, is death. Stay on the boat. So I kept my tether short, and stayed clipped on.

When we reached Antigua, customs asked "how many aboard?". The next question..." and how many did you start with?".
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Old 03-03-2016, 21:00   #135
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Re: Man Overboard with Auto Pilot Engaged!

Know this is an old thread...Just curious if anyone attempted this and made video (grabbing trailing line)


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