look at the following ISAF document and search for "stanchions" to get an idea of what the design specs are. The lifelines are part of the supporting system, so the full 200lb accelerated load won't go straight across one stanchion, and if it does it will deform to absorb the energy but not break, and if it does break there are still 2 lifelines through it that can each hold a multiplie of the forces involved.

http://www2.sailing.org/offshore/2007/OSR2007_Mu4_270607.pdf

 

True on all accounts. A lifeline is meant to act as a reminder of where the edge is and as a handhold for walking. They also keep large items on deck (e.g., sails). I recall reading that the criteria is something like 50 lbs of lateral pressure before it fails. Not much.

In reality, a properly through bolted stanchion base will probably hold the weight of a falling crew member, but the stanchion will probably fold over.

The relative fragility of stanchions is why I strongly discourage people attempting to hoist themselves onboard by grabbing the thing. My wife also has a habit of grabbing it to pull the boat in closer to the dock. I cringe when she does that but her name is on the boat, so what can I do?

 

My wife also has a habit of grabbing it to pull the boat in closer to the dock. I cringe when she does that but her name is on the boat, so what can I do?

Brace the one she grabs? Been there.

Actually, my wife has arthritis and we do make adjustments. I carry a small tackle that I use to pull the boat to the dock and to hold it steady. It goes from cleat to piling/cleat, so there is no strain. In fact, I find it very handy when I'm loading and unloading too. I have been careful to chose a loop for one end that will snap should I forget to release it and the tide changes!

 

The force would be distributed to all of the stanchions by way of the lifelines. If your lifelines are attached to the bow and stern like most boats you might end up with a bent stanchion or two but you're not going to break that SS lifeline (if it's in good shape, no corrosion, etc).

 

Our stanchions are connected to the anodized toerail ( an 80s C&C design )thus little to worry about interms of rebedding the deck or having them become wobbly. It is a good design EXCEPT they tend to get hung up on pilings when docking if you are not careful. They will handle the load (since the lifeline is swaged on and adjusted correctly with adjustable barrels) of a 250 lb man easily.

Dave

 

Lifelines are just a reminder that you're about to go overboard. In many cases, you can't rely on them to keep you aboard, especially if they're coated with vinyl, since the stainless steel may be corroded badly beneath with no real visible signs of it. Also, on many boats, the stanchions aren't tall enough to prevent a taller person from going overboard.

 

The force would be distributed to all of the stanchions by way of the lifelines. If your lifelines are attached to the bow and stern like most boats you might end up with a bent stanchion or two

I forgot about that. Since the wire is attached at both ends, the stanchion can't fold completely over. The strength or the wire & fittings will stop it from happening.

 

Sure glad I'm on a diet--gotta' get skinny again!

Cheers,

Gary

 

I was told once that, when you are at sea, treat the edge of the boat like it was a 1000 foot cliff face and treat the lifelines like they had 10,000 volts on them.

Obviously neither are true, but you get the idea. The lifelines should be the last in a long line of safety layers designed to keep you on the boat.

 

When I go forward in bad weather, the life lines are in my right hand (if stbd) and the cabin top hand holds are in my left hand. Forward of the cabin top, I'm on my knees. Of course, if it's really bad, will employ a harness on a jack line. High toe rails are very helpful to stand against...(forgot the nautical term)

 

SD is right about the possible corrosion of the lifelines under the vinal. I prefer vinal over plain wire, and am will to spend $300 every 5 years and replace them as regular maintainenece. I couple of my firends of my friends have bare lifelines and have gotten a small burr or broke a wire in the strand and it tore a nice hole in the jibs as it slip over the lifeline.

Also as SD and others have mentioned or intimated. They are really not safe, but a safety net and shoul,d noit be relied upon when more prudent safety should be followed.

Dave

 

SD is right about the possible corrosion of the lifelines under the vinal. I prefer vinal over plain wire, and am will to spend $300 every 5 years and replace them as regular maintainenece. I couple of my firends of my friends have bare lifelines and have gotten a small burr or broke a wire in the strand and it tore a nice hole in the jibs as it slip over the lifeline.

For bare wire, in my opinion Dyform is the way to go - very smooth on the hand, and stronger, as well...

I cringe every time I see fenders hung from lifelines, I can't believe how widespread this abuse of the integrity of lifelines and stanchions has become... Sailors who routinely do this deserve the deck leaks that will result from the working of their stanchion bases created by this ungodly practice (grin)...

 

I like the 1000 foot cliff and 10,000 volt lifeline analogy. Gotta remember that.

In the Navy, the Chiefs "strongly" discourage leaning bodies or feet on the lifelines. I get yelled at a lot. Gotta stop doing that.

 

We were caught in a strong blow, strong enough to snap the ties on the dingy that was lashed to the foredeck. And I'm talking a big RIB that is heavy and was stowed upside down (that storm has been documented on this board).

The wind peaked around 70 gusting 80 when the tie snapped and the dingy went into the air like a child's balloon. The other two ties however held on and the dingy ended up on it's side against the lifelines with the full force of the wind in it.

The stanchion that was right there bent through about 20 degrees and when the gust relaxed the dingy fell back onto the deck and we had an opportunity to re-secure it. The stanchion base has not been repaired since then because there is no repair required. The stanchion was put into a 100 ton press and straightened and reinstalled with no noticeable stress on the aluminium other than tool-marks.

Your lifelines, if properly installed and in good shape are waaaay stronger than many of the earlier posts give them credit for. I don't believe that an adult thrown against them is likely to break anything except maybe the adult.

 

Andre--

I'm not saying that properly installed and maintained lifelines aren't strong... just that you shouldn't rely on them to keep you on the boat, especially if the boat isn't yours and you don't know how they've been maintained. I'd note that even you are heavily qualifying your post by saying:

Your lifelines, if properly installed and in good shape are waaaay stronger than many of the earlier posts give them credit for.

In so many cases, the lifelines haven't been maintained or regularly inspected. Also, a lot of lifelines, especially on smaller boats, are only 24" tall or so, and unless you're a midget, that's not tall enough to keep you aboard, but just tall enough to trip you and ensure you end up overboard in many cases.

 

what about using the amsteel stuff or some other form of heat-treated dyneema braid for lifelines? Other than the risk of cutting it with a knife, could it work as well as traditional vinyl-coated steel cable?

 

There was a study of this question. US Naval Academy/US Sailing Lifeline Failure Study you can google it.
They found that stanchions failed at 1,000#. This was usually where the middle wire went thru it and the lifeline just folded over to half its height. Wire terminals failed at 3-5000# and the wire failed at about 7,000# Keep in mind that the tension force on the wire/terminal is several times the lateral deflection force.

Thier recommendations were:
Use 9x16 wire, avoid gates, make sure there’s adequate backing plates, meet Offshore Ocean Racing Council Specs, keep the lines tight and inspect/maintain them.

Usually lifelines are kinda’ low to keep you onboard if you fall against them. I use a track and harness line when single handling or if there’s a risk of going over. Here in the northwest with 40 deg water… fall overboard and you soon die.
I looked into jack lines but found that I couldn’t get them tight enough to keep me on the boat side of the lifeline . Deflecting a 30 ft. jackline 1ft. with 200# lateral load puts about a 1.500# of tension on the wire That’s why I went to a track

 

....I use a track and harness line when single handling or if there's a risk of going over....That's why I went to a track

Got pictures of that track idea? I am curious because in the NE, we have the same water temp issues.

 

When we are at sea we seldom go onto the foredeck but spend a lot of time on the poop and on the rear cabin top.

We have decided to build a new radar arch and in the process we are having solid hand rails at a height of 800mm put all the way around the stern to come up to the entry in the cockpit on both sides with a proper closing gate at the stern boarding ladder.

We had a near-miss with a MOB once when in the middle of the ocean on a beautiful day, we decided to have a shower under the hose on the rear deck. My wife was sitting on the edge of the cabin top fully soaped up when the boat lurched and with her soapiness and the same on the deck, she went quickly sliding toward the transom and it was a major challenge to arrest her motion and keep her on board. Sounds like a funny story but it was scary at the time and selling the idea of solid hand rails has been real easy since then.

 

The arch with handrail sounds like a very good idea, and netting might not be a bad idea.

 

I learned the hard way on the J24 and just beefed things so the load is distributed over enough surface area of the deck so its a NON_ISSUE

 

Some people won't maintian anything no matter how much emphasis you put on the importance.

The one below resulted in an MOB...

Electrical, plumbing/seacocks, bilge pumps, rigging, lifelines etc. etc. are all SERIOUS items that if neglected and not maintained can potentially kill you or a crew member..

 

I'm still having a vision of my wife, fully soaped, sitting on my cabin top on a beautiful day.

I'm sorry, what were we discussing again?

 

Toe Rail stanchion holders on C&C. Good idea. No messing with the deck and having stanchions come loose or spider cracking the gelcoat over time. Easy to install and fit right over the toe rail and are bolted on
Stanchions are held in the holder with two bolts so very secure. Just watch out for the pilings when doking as these are a little more outboard than the regular stanchion placement on most boats.

Dealer of Bavaria Yachts, Contest Yachts and C&C Parts

 

Cheese slicer

We use 1/2 inch 3-strand Dacron for lifelines. The reason: We want something to be able to grab at the last second in an emergency, and salt-water on a small-diameter stainless steel cheese slicer doesn't get it. More windage, yes, but more strength, and something to grip in an emergency. It looks great, too and is easy to replace without swaging tools, etc.

 

We use 1/2 inch 3-strand Dacron for lifelines. The reason: We want something to be able to grab at the last second in an emergency, and salt-water on a small-diameter stainless steel cheese slicer doesn't get it. More windage, yes, but more strength, and something to grip in an emergency. It looks great, too and is easy to replace without swaging tools, etc.

You may want to analyze the force vectors of a 200-lb person pulling directly down on your lifeline. I would be concerned that with the way lifelines are routed around the stancions, the resulting tension from a 200-lb downward force might be much higher than you realize. Then compare that number to the line's maximum working load.

Also, do you do anything to protect against chafe at the stanchion tops?

 

A less condescending reply would have been appreciated.

My concern was over the "amplification" of static tension because of the "guitar string" geometry of lifelines. This geometry is very different from a mountain climber pulling straight down on a lifeline described in your link:

As θ gets small, T can get very large - which I had always believed was why steel lifelines are typically used in this application. (Same reason why steel guitar strings last longer than other materials.) Stretching of dacron line would affect θ in a way that reduces T, but that benefit may be offset by severe chafing and cutting that could occur at the stanchions when the line is under tension (and which was pointed out in the link you provided).

My comment was related to static tension only. The dynamic effects described in your link are a separate issue from what I was mentioning. But when you consider the dynamic effects, my concern becomes even greater. Take the extra dynamic stress caused by decelerating a falling person from his rate of fall to zero and divide it by sin θ, and you are even more likely to exceed the maximum break load and/or cut through the line at the edge of the stanchion.

My point is still the same - I believe many people neglect the unique geometry of the rigging of lifelines, and how that can cause very high amounts of tension. You can belittle it by calling it high school physics if you want - it still seems to be neglected by many.

 

For what it's worth, if one intends to do an analysis of a lifeline arrangement, one must look at the entire cable system, from end connection to end connection. In most cases, lifelines terminate at pulpits at the bow and stern although on some smaller yachts, they may angle downward from the last fore'n aft stanchion to deck fittings near the bow and stern. For the most part, stanchions are not intended to take horizontal loads (in bending) but rather to simply to hold the lifelines in position at height and take vertical loads much as do the struts in a tent or the spreaders on a mast. When a load is thrown against the lifeline from inboard, it will move outward and tension up just as does a bow-string when the bow is drawn. The tension in the line is carried by the connections at the bow and stern pulpits. Any loading out of plane is carried by the stanchions acting as struts, hence a little "flex" at the top of the stanchion is desirable. Accordingly, however, one wants tight lifelines so that there is as little "give" or horizontal displacement in the lines before they are tensioned.

Where lifelines and stanchions may fail is with an inward pull rather than an outward push as the lines generally follow the curvature of a hull and hence cannot go into tension when loaded inward. An inward push on a stanchion can seriously load up a base with "prying action" and can easily damage a deck. (I vigorously oppose anyone grabbing or pushing on a stanchion when we're moving the boat about by hand in a marina!)

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hmmm interesting. my solution would be to have more lines higher and beefier, also stretch a net throughout.

Remember that cables are often used to keep car on roads so it should not be hard to rig a system to keep a person, on board a boat. the forces are smaller.

Given that everything is over engineered with a safety factor (esp boat items i.e a triple inter braided tubing with an max load of 80psi on a fitting (double clamped) with a working load of 2psi and a max of 10psi) Really if you do your inspection and maintenance there should be no problems just make sure you use the right material and if its non standard do the math on it.