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Old 16-07-2016, 06:54   #1
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Life Lines ... again ...

I know there are previous discussions about life lines, I read many of them and I was involved with a number of them ... but like the attorney using an old dispelled defense ... the court generally allows the argument, or at the least, allows the jurist to make his case to the judge(in chambers), to see if the new twist is a viable argument ... so here goes.

I have just read two articles that cause me concern, about life lines and concern about "what", the particular articles are saying.

US Sailing, issued a report about using Dynemma/Spectra Life Lines, and that report states that Dyneema/Spectra is "15 times stronger than steel fiber of the same weight".

A Practical Sailor article is quoted ..."one of the key attractions ...", "... ropes to be made as strong as stainless-steel wire of equal diameter, yet weigh a fraction of the wire that they replace."

I don't understand how these two statements can be reconciled.

I have handled Dyneema ... and I have handled steel cable ... the weight difference is well like the difference between very lightweight synthetic line and comparatively heavy(much more than 15 times), steel ... no comparison ... no way.

So, which statement is true ... or are both statements incorrect?

Practical Sailor continues, in conclusion, to note that the use of dyneema/Spectra on actively maintained racing boats(probably meaning the "big-money", boats), may not be the same as the less actively maintained every-day boats most of us operate.

Now, part of my research(?), is my willingness to do away with a 24" high tripwire, in favor for a line running inside at the edge of the cabintop, with the idea that I'd rather be grabbing something toward the interior of the boat, that to grab something toward the exterior of the boat. I figure that my handhold makes a better turning point inside, rather than outside ... think of May Lou Retton, on the parallel bars.

The Practical Sailor article also states the ONLY viable reason for Life Lines"(as we know them), in this lead-in statement ... "Lifelines are called “guardrails” by British sailors, but regardless of their designation, they represent a handhold of last resort."

"Last Resort" ... not first resort, not best resort, not best alternative ... the article doesn't even state an adequate resort ... just, simply put ... "Last Resort" ... the as the last chance. This leads me to believe that the statement is almost saying to have other ways to keep one on the boat and that the lifelines are NOT there to aid going forward ... they are only there as a "Last Resort" ... maybe like having a "donut" spare tire, instead of a full-sized spare tire ... adequate as needs be to get you to the next service station ONLY.

So, now after reading these articles, I think the Stanchions, that I've taken off(for re-fiberglassing & re-seating), are now going back on ... a little more firm & stronger than before, but not for the "everyday", use of going forward. Interior lines will handle that duty, and I'll feel more confident that a big jolt, that might make me go airborne will also send me(maybe flying), toward the interior of the boat, where, maybe, the lifelines on the opposite side of the boat might catch me ... I now have a renewed viewpoint.

Jayne Mansfield, star/sex goddess, of the 60's, was killed in a car accident. She was "decapitated", by the sun-visor. If one tries to "break", relatively weak sewing thread by wrapping it in the hand and pulling hard and fast, that person often ends up with an intact thread and a hurting hand.

Even as a line of last resort, shouldn't we sailors be looking at enlarging the size of lifelines? Is there anyone here that thinks he/she, can actually hold onto a lifeline(the way they are now), without losing grip or damaging their hands? After all, many of us wear gloves to aid in gripping and to reduce burning.

I think I want larger lifelines ... 3/8", or even 1/2" ... much easier on the hands in a violent toss ... actually, just barely large enough to get a "real grip", on this Life Line of "last resort".

My dream ... Interior lifelines of 1/2" ... maybe even 5/8" or 3/4" or so on the cabintop, then maybe another 6" in height on my lifelines, but with 3/8" or 1/2" line ... better grip when I'm trying to grab that last resort line.

Just some random thoughts ... but, the lifelines are going back on ...
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Old 16-07-2016, 07:37   #2
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Re: Life Lines ... again ...

consider your lifelines the guide that allows you to know where the edge of your boat is. nothing more.
they are not life savers.
they are not intended to keep you on a boat.
lifelines are only as strong as the stanchions holding them.
do not consider them to actually live up to their name, as that was NOT their intent.
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Old 16-07-2016, 08:06   #3
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Re: Life Lines ... again ...

> "I have handled Dyneema ... and I have handled steel cable ... the weight difference is well like the difference between very lightweight synthetic line and comparatively heavy(much more than 15 times), steel ... no comparison ... no way."

Your perception of comparative weight is inaccurate.
Steel is only about 8 times heavier than dyneema. (SG of around .97 compared to around 8.0)


> "15 times stronger than steel fiber of the same weight".
This is correct.

When the Dyneema and steel are made into wire or rope, the difference can vary to a certain extent, depending on the construction - but a couple of examples from supplier figures:

6 mm SK75 weights 2.3kg per 100m.
6 mm 7x19 wire weighs 13.6Kgs per 100 m

10 mm SK75 weighs 6.1kg per 100 metres.
10 mm 7 x 19 steel wire steel weighs 40.1kg per 100m

So in this instance, steel is only 6 to 6.5 times heaver SK75.

Now to strength

Breaking strain
6mm SK75 = 4700kg
6mm 7x19 = 2086Kg

10mm SK75 = 10700
10mm 7 x 19 = 5763

So same diameter, roughly twice the breaking strain.

Combining the above figures, we can look at strength to weight:
Double the breaking strain for 1/6 to 1/8 of the weight
which equates roughly to the same breaking strain for about 1/15 of the the weight.

Which is what the first statement said

>"ropes to be made as strong as stainless-steel wire of equal diameter, yet weigh a fraction of the wire that they replace"

This is possibly conservative.

As you can see in the figures above, you actually get considerably more strength for the same diameter, at least with SK75 v 7x19. Different HMPE ropes and different wire types will of course vary in their relative strengths to some degree and it may well be that some HMPE rope is indeed only the same strength as some wire of the same diameter.


Bottom line. Both of the statements reasonably accurate.

As for lifelines and handholds:

I agree, lifelines are not there to help me go forward. They are there to stop me from going over the side. I don't use them as handholds.

Lifelines have kept me in a boat a couple of times. On neither occasion did I grab them with a hand. They stopped me from sliding off the boat when I hooked an arm and/or leg around them.
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Old 16-07-2016, 08:25   #4
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Re: Life Lines ... again ...

I wrote the us sailing article, and thinwater (also here) wrote the practical sailor article (I believe).

The us sailing article is a bit out of date, because dyneema has since been banned for lifelines for racing (for monos). Because there were several cases of it being cut/chafed accidentally.

As to size - sure go bigger, will always be safer. The racers do not because of windage (and weight) but no reason for a cruiser not to. I found 3/8" to be a nice compromise (except for the cost in dyneema).

Some cruisers go with 1" steel tubing for top lifeline a swear by them. There are some drawbacks, but in terms of hand grip security it is good.

Lots of reasonable options, with lots of trade-offs between them
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Old 16-07-2016, 10:07   #5
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Re: Life Lines ... again ...

I've thought about what might keep me on the boat, if I lose my balance, and conclude that only, if I can can drop to my knees before I'm tossed overboard, am I likely to be kept on board by the lifelines. I agree that the jack-lines make most sense in the middle of the boat, though it implies more clipping and un-clipping of two tethers, because of the need of more anchor points. Of course, if you always travel on the windward side of the boat, it doesn't prevent you from being pitched over that side.
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Old 16-07-2016, 10:21   #6
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Re: Life Lines ... again ...

Most installations are insufficient...may as well be called "death lines"
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Old 16-07-2016, 10:31   #7
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Re: Life Lines ... again ...

Quote:
Originally Posted by zeehag View Post
consider your lifelines the guide that allows you to know where the edge of your boat is. nothing more.
they are not life savers.
they are not intended to keep you on a boat.
lifelines are only as strong as the stanchions holding them.
do not consider them to actually live up to their name, as that was NOT their intent.
I am living proof that life lines can and do save lives. Case in point, wife at tiller in storm jibes the boat as i'm heading forward beside cabin. The boom whacks me in the side of the head and knocks me toward open water. Luckily my heals jammed the side of the cabin whilst my front of my legs were being supported just above my knees by the lifeline as my body was flung towards the water bending me at the waist and my outstretched hands hitting the water . If that life line would have snapped from the enormous pressure I put on it ,I would have been swimming in water cold enough to last maybe 10 minutes 10 miles from the nearest land with no cell phone or VHF. My wife didn't have a clue how to turn the boat around. She was screaming crying as lightning was zapping all around us and the thunder was deafening. Needless to say I pulled myself aboard the tossing 23 ft sailboat and continued to work on the headsail while the torrential rain washed all the blood from my head wound off the deck. Nobody can convince me that lifelines can't save lives.
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Old 16-07-2016, 13:09   #8
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Re: Life Lines ... again ...

I am replacing my 2 foot stanchions with three-foot stanchions. 3 feet is much closer to the vertical center of mass than 2 feet.
I like the idea of a rope running along the cabin top which can be grabbed easily.
On my Pearson 35, because we have a Dodger, stepping out onto the side deck is the most dangerous situation. The temptation is to grab on to the top of the dodger which in a seaway is bad idea
Is anyone encountered that situation and found a good way to deal with it? I'm thinking about removing the side panels of the dodger but leaving the front panel and the Bimini in place
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Old 16-07-2016, 13:55   #9
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Re: Life Lines ... again ...

I have new respect for the forces that could be involved on a sailboat.

Luckily, my "encounter", was in 3+ feet of water, on a Pearson 26 with a fin keel.

The boat was alternately(wave action), going from floating to dragging(and bouncing).

Some of the bouncing was rather violent and I was imagining something, possibly much worse in washtub waters with shifting winds.

When the boat is hit with the right forces, one doesn't have time to kneel down(to pray or to get lower on the deck), and the speed at which the force hits, one doesn't always have time to brace for the force.

This means that one has to be firmly attached to the boat, regardless of the strength of handholds or lifelines.

I think anything that serves as a handhold, should be about 1" or so in diameter ... anything else and the grip that you think is good, will fail you ...

Lifelines, in these situations, I think, serve absolutely no value whatsoever, with a purposeful handhold ... I think the only values of lifelines is the happenchance that they just might catch a falling person ... in my mind this has again led me to believe that their purpose is valuable ... just keep your &*#$*&@#&^$% hands off the lifelines ... if a person wants something to grab, set up a "permanent", line(jackline?), along the top of the cabintop, about at the transition from cabin side to the cabin top, and loose enough to "comfortably", hold on, while on the way forward. I see Jacklines as a separate issue, to also be additionally employed in rough weather.

I would guess there have been studies that compute the actual forces that might be exerted during bad seas ... and I'll bet those numbers can be astounding ...
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Old 16-07-2016, 17:09   #10
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Re: Life Lines ... again ...

Quote:
Originally Posted by pdenton View Post
I am replacing my 2 foot stanchions with three-foot stanchions. 3 feet is much closer to the vertical center of mass than 2 feet.
I like the idea of a rope running along the cabin top which can be grabbed easily.
On my Pearson 35, because we have a Dodger, stepping out onto the side deck is the most dangerous situation. The temptation is to grab on to the top of the dodger which in a seaway is bad idea
Is anyone encountered that situation and found a good way to deal with it? I'm thinking about removing the side panels of the dodger but leaving the front panel and the Bimini in place
Do you not have side grab rails on your dodger? If not, you should. I find that is the MOST stable place when going forward or coming back aft.
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Old 16-07-2016, 17:32   #11
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Re: Life Lines ... again ...

Quote:
Originally Posted by zeehag View Post
they are not intended to keep you on a boat.
lifelines are only as strong as the stanchions holding them.
do not consider them to actually live up to their name, as that was NOT their intent.
Maybe your lifelines aren't worth **** but some are fine. Stanchions only hold the lifeline up, they don't determine the strength, the ends do. The entire lifeline all the way around the boat acts as a big bungee. You could tow our boat from the lifelines.
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Old 16-07-2016, 17:34   #12
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Re: Life Lines ... again ...

good for kids /pets/ad trawler mesh
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Old 16-07-2016, 23:02   #13
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Re: Life Lines ... again ...

I second Stu's comment about having grab rails mounted on the dodger. I could not have stayed on board without them.

One other idea for those who have a similar rig to mine:
Our ketch has a pair of main backstays that terminate at the scuppers just about even with the mizzen mast. Whenever sailing on ocean, I rig 1/2" lines from these backstays horizontally to the forward main shrouds, at chest height, on both sides of the boat. You would think the rope would slip up along the backstay and go slack, but I use about 5 wraps around the stay and it does stay put. I put a lot of tension in it.

This area is probably one of the most dangerous areas on the boat, as the deck is narrow here and I'm walking, or perched on the cockpit coaming while tying in the bag of sail after reefing, or furling the mainsail, whereas forward of the mast I stay very low, on knees if it's really rough.
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Old 17-07-2016, 03:11   #14
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Re: Life Lines ... again ...

Guard Rails "Guard" against you going over the side and are also useful for drying your laundry.

Life Lines are run along the deck to clip onto with your safety harness in heavy weather to save your life.

Never heard anyone call guard rails life lines or vice versa. Have however heard them called OS Lines where OS stands for OH ****!

This from a native speaker of Her Majesty's English

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Old 17-07-2016, 04:29   #15
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Re: Life Lines ... again ...

Quote:
Originally Posted by kas_1611 View Post
Guard Rails "Guard" against you going over the side and are also useful for drying your laundry.

Life Lines are run along the deck to clip onto with your safety harness in heavy weather to save your life.

Never heard anyone call guard rails life lines or vice versa. Have however heard them called OS Lines where OS stands for OH ****!

This from a native speaker of Her Majesty's English

Keiron
It's a matter of local terminology. In a lot of the world, lifelines run through stanchions. what you are calling lifelines are known as jacklines or jackstays in those areas.

(This also from a native speaker of Her Majesty's English )
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