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Singlehanded MOB Procedure--Outside Box Idea

Mar 26, 2011
2,868
Corsair F-24 MK I Deale, MD
Ideally, you stay on the boat. Agreed, let's not flog that topic. I've written much about tethers, jacklines, and hardpoints.

The problem with a trailing line is that the sailor cannot hold it. So let's just stop the boat.
  • If we put the helm over the boat may tack off in a different direction. Effectiveness depends on the set of the sails and the course.
  • If trip the autopilot, the boat many not head up (sail balance) or may still drift too fast.
  • If we program the pilot to head up... good luck if the chute is up, and even if not, it may still take off.
So, assume you are back there on the rope getting dragged. What do you wish for, other than crew? A big damn anchor to just stop the boat. Anything that stops the boat.

So why not just stop the damn boat?

Why not trigger the release of a parachute sea anchor? Remember we are talking about small boats, generally less than 27 feet and less than 6000 pounds. A 5' parachute will slow the boat to less than 1 knot, no matter the engine, sails or course. The boat will stop.

  • I've tested sea anchors and drogues by throwing them off the back of moving boats dozens of times, Faster than this with a 9000-pound catamaran. I did this to test the anchors with high force. Never a failure, just a firm stop.
  • You do need enough elastic rode to buffer the stop (calculation varies with the mass and speed, but generally 50-100 feet of climbing rope is about right). You need certain floats and rigging; these are standard for sea anchors and are well understood.
  • The swimmer does not need to hold the line. A brief 5-pound tug will do the job.
In fact, I tried it again today, this time with a deploy-by-pulling-line rigging. The whole business fit in an 8" x 24" stuff sack, including all rigging and floats and was bungeed to the aft cockpit floor. We were under full sail at about 7 knots. The rigging fed out, and when the end of the rode was reached (100 feet), the boat stopped in a few seconds, moving only 0.7 knots with full sail pulling (broad reach). A cripple could pull themselves to the boat, following a nice tight line. If they slip, they are caught by the chute.

This is rather like killing ants with a hammer. It is idiot proof and make no assumptions about sail selection, balance, or course. There are no special installation, other than placing an eye over a stern cleat. The sailor does not need to understand what is in the bag. The force on the boat was less than 500 pounds. Sort of like a whole-air plane parachute with a long floating rip cord.

So as long as we are talking about smaller boats (less than 27 feet, less than 10,000 pounds), what am I missing? The only obvious problem is if you cannot find the floating line.
 
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Gunni

.
Mar 16, 2010
5,937
Beneteau 411 Oceanis Annapolis
So, where is the trigger line relative to the MOB?
 

SG

.
Feb 11, 2017
1,670
J/Boat J/160 Annapolis
Assuming you are attached to a rope, aft of the boat, do you get taken out by the drougue as it deploys?
 
Apr 22, 2011
700
Hunter 27 Pecan Grove, Oriental, NC
So instead of hooking onto something that will keep you attached to the boat, you hook onto the drogue deployment lanyard? Kind of like the outboard motor shutoff safety lanyard.
 
Mar 26, 2011
2,868
Corsair F-24 MK I Deale, MD
a. I assumed the trigger to be a long floating line, but one of my buddies suggested it could also be a tether to the person of some sort, perhaps like a retracting dog leash. Just a water cooler conversation at this point. You just need to get the deployment bag into the water; the flow does the rest. Many possibilities, all worth testing to see what works best. They are also not mutually exclusive (you could have several triggers). However, you need to guard against a mechanism that would allow the chute to snatch you off the boat if is somehow deployed by accident (if you were tethered to the chute, when it deploys, you are going to follow it!). Like deploying a sea anchor in a storm, once it is in the water, the rope must run clear and nothing is stopping it until it fills and the boat stops.

b. Yes, when the chute deploys, the swimmer would drop back the distance of the chute rode (50-100 feet). But it would not have to be so; the trigger could simply deploy the chute, dropping the swimmer back only 2-3 feet. I'm not sure how big a deal this is, since once the chute deploys, the boat really does stop, even if the engine were full throttle or the chute was up.

One good thing about being dropped back is that while the chute is deploying and you are drifting back, you are not being ripped off the rope; you are just drifting. For example, with the boat moving at over 7 knots, you would not be able to hold onto a fixed rope; you would slide to the end and possibly lose your grip. Drifting back 50-100 feet with a slack rope might be better. You can, of course, pull the rope in, hand over hand, while you wait. This will actually speed chute deployment.

Before someone asks, yes, this could be engineered for big boats. I know how to do it, but I would rather focus the conversation on small boats that are often single handed and which are difficult to rig truly effective tethers. I think it is a much better and more practical application.
 
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Joe

.
Jun 1, 2004
7,357
Catalina 27 Mission Bay, San Diego
So instead of hooking onto something that will keep you attached to the boat, you hook onto the drogue deployment lanyard? Kind of like the outboard motor shutoff safety lanyard.
Yes, but don't you also want your tether to allow you to move around the boat securely, not just trigger a "kill switch"?
Are we thinking more of a type of "dead man's switch", maybe electronically, or hydrostatically activated like an auto pfd?
Do we want to rely on electronic triggers or stick to something mechanical?
Is a retrieval line a requirement, or just to stop the boat.
........
When I sailed my Nacra out in the ocean, I would loop the mainsheet through my harness/pfd. Falling off the cat, the sheet kept me attached but, instead of being dragged through the water, the added tension on the sheet either caused the boat to round up or even capsize... (beach cats are quite easy to right, btw)
.....
A small or lightweight boat, would respond to this technique. larger boats it becomes more complicated. Thinwater's experiments seem to work for all sizes of boats...so the triggering method becomes the challenge. Again.... electronic or mechanical?
 
Jun 11, 2011
1,243
Hunter 41 Lewes
Someone put up an interesting video about amonth ago with a tether line that brings you a board then launches a drouge and sends you and the board back to the boat. Injury and unconsciousness are off the table with this system I thought.
 
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Gunni

.
Mar 16, 2010
5,937
Beneteau 411 Oceanis Annapolis
In this scenario it would be better to carry the drogue on the crewmember not the boat...and tether with a double line - one for the crew, one for the drogue. Deploy the drogue and pull yourself aboard.
 
Apr 5, 2009
1,519
Catalina '88 C30 tr/bs Oak Harbor, WA
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Mar 26, 2011
2,868
Corsair F-24 MK I Deale, MD
There is an electronic MOB system designed for power boats that kill the engine if anyone falls overboard. You could rig this to a "drogue cannon" that used a solenoid to release a spring-loaded drogue. I would have it drop a small mushroom anchor attached to the head of the drogue and let it pull the rest out of the holder.
https://www.fisheriessupply.com/fell-marine-inc-mob-plus-basepack-multifob-72-380-206
Also an interesting idea. I've seen videos and read reviews that suggest it may take 100-150 feet to trigger sometimes. Thus, the swimmer would probably be a little farther than that (say 150 feet from the chute), without a rope in their hands.

Of course, there is no reason you can't do both.

You won't need the mushroom anchor. In fact, all you need to do is drop a 6" drogue a few feet astern and that will do the rest.
 
Jan 4, 2010
946
Farr 30 San Francisco
NKE autopilot has a mode that if contact with the remote is lost the boat goes head to wind. So you can spend the last hours of your life swimming after your boat that is just drifting a little bit faster than you. Swimming in clothes and lifejacket maybe you can do 1 knot.
 
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Gunni

.
Mar 16, 2010
5,937
Beneteau 411 Oceanis Annapolis
Yeah, you are not getting back on the boat alive unless you are tethered or the boat comes to you.
 
Aug 22, 2011
1,106
MacGregor Venture V224 Cheeseland
triggering the chute hmmm.....

Exceeding a predetermined force on body tether...

Perimeter Trip Line...

Motion Detector

Special Button on the bat belt...
 
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Oct 19, 2017
6,820
O'Day 19 Littleton, NH
The best reference (not a reliable one) says the average person swims at about 2 mph. women, apparently, average 10% less speed. Add clothes and life vest and you may be down under 1 mph. With deck shoes, 1/4 mph (just guessing here).

I love the drogue deployment idea. Maybe a tug on a box cover attached to the transom and the shoot falls into the water. If it was connected to the line that you pulled on, it could reel you in. Or, the shoot's line would be longer than the trip line and it wouldn't open and stop the boat until you were dragged past it by the boat.

I see no reason why you couldn't also connect a trip to the main sheet cam block and release the main.

You have to consider the circumstances under which you are likely to go overboard. Rough seas when something happened that forced you out of the cockpit. Maybe you are reefing, maybe a line broke and a sail is loose and you are on the foredeck trying to tame a loose jib. Maybe the wind shifted or a wave knocked you off course a bit while running downwind and the jibing boom knocked you in the drink. Will your system work, is it easier or harder to slow a boat under those conditions? Putting the rudder hard over could knock the boat down, cause an uncontrolled jibe and maybe break something essential like the mast.

An auto pilot or wind vane that brings her up into the wind would be great too. Whatever the system, getting rescued faster is better.

- Will (Dragonfly)
 
Mar 26, 2011
2,868
Corsair F-24 MK I Deale, MD
The best reference (not a reliable one) says the average person swims at about 2 mph. women, apparently, average 10% less speed. Add clothes and life vest and you may be down under 1 mph. With deck shoes, 1/4 mph (just guessing here).

I love the drogue deployment idea. Maybe a tug on a box cover attached to the transom and the shoot falls into the water. If it was connected to the line that you pulled on, it could reel you in. Or, the shoot's line would be longer than the trip line and it wouldn't open and stop the boat until you were dragged past it by the boat.

I see no reason why you couldn't also connect a trip to the main sheet cam block and release the main.

You have to consider the circumstances under which you are likely to go overboard. Rough seas when something happened that forced you out of the cockpit. Maybe you are reefing, maybe a line broke and a sail is loose and you are on the foredeck trying to tame a loose jib. Maybe the wind shifted or a wave knocked you off course a bit while running downwind and the jibing boom knocked you in the drink. Will your system work, is it easier or harder to slow a boat under those conditions? Putting the rudder hard over could knock the boat down, cause an uncontrolled jibe and maybe break something essential like the mast.

An auto pilot or wind vane that brings her up into the wind would be great too. Whatever the system, getting rescued faster is better.

- Will (Dragonfly)
The method assumes nothing and requires no other action. The engine can be full throttle and the chute up. The boat simply stops.

You don't need to shoot it out. During my last test, I flaked everything into an 8 x 24 stuff sack and secured it lightly to the cockpit floor (open transom), rather like a skydiver's chute. The rip cord, if you will, is a long, floating line. We were on a broad reach at 7 knots and adjusted nothing. When the rip cord is pulled, it deploys like a skydiver's chute, catching the entire boat.

To get going again, I transferred the rode to a winch, pulled the chute close, and tripped the head using a short line and float provided for this purpose (standard sea anchor rigging). We did not drop sail at any point. It did not cause the boat to jibe or change attitude significantly. Once recovered, we just sailed off.

You do not swim back to the boat. You pull along a line that is nice and tight. Very easy even in full kit.
 
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Jun 11, 2011
1,243
Hunter 41 Lewes
If the water is anything but calm and you go over the life line, even if you don't get wet, with the boat moving and waves slapping I'd put odds on you not even getting your tired butt back over the life lines and onto the deck. Jack lines and tethers should really be set up so that you can not go over the life lines or your chances get slim and fast.
 
Mar 26, 2011
2,868
Corsair F-24 MK I Deale, MD
If the water is anything but calm and you go over the life line, even if you don't get wet, with the boat moving and waves slapping I'd put odds on you not even getting your tired butt back over the life lines and onto the deck. Jack lines and tethers should really be set up so that you can not go over the life lines or your chances get slim and fast.
Obviously. I have published on this topic and have a related article coming out in a few days in Practical Sailor (safety snaps).

This thread is more of an exercise in imagination.

What possibilities does being able to quickly stop the boat open to us? Perhaps you have crew that couldn't maneuver the boat back to you. Perhaps you've got a guy tethered over the rail and you just want to stop before he drowns. Perhaps some that are not even MOB-related.
 
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