lifeline height

Discussion in 'Boat Design' started by dreamer, Mar 22, 2009.

  1. dreamer
    Joined: Nov 2004
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    dreamer Soñadora

    Hello Folks,

    I have been looking without success to find information about lifeline height. Nearest I can tell, there are no regulations for such a thing on private craft, but I do want them to be high enough to be practical but not too high that it would look dorky.

    I'm kicking around an idea for a 41' boat. I've used 36" wich seems a bit high, but I don't want to be so low that it would flip someone off the boat if it caught them behind the knees.

    Portions of the lifeline will be, well, 'line' while the rest will be rigid tubing.
     
  2. marshmat
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    marshmat Senior Member

    Three feet sounds about right, yes. Anything under 2' is more of a tripline than a lifeline. At a recent boat show I was looking at one power cruiser that had 16-18" high rails around the foredeck- and this was advertised as a selling point, being higher than some of the competition. The foredeck of this thing scared the you-know-what out of me while it was sitting on blocks; I can only imagine what the crew must think when asked to go out on such a deck while the boat is pitching around in a harbour entrance.
     
  3. dreamer
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    dreamer Soñadora

    Thanks Matt,

    I suppose if you are crawling around on deck or lying there in the nude on your back catching some rays, 18" - 19" lifelines would be a bonus ;).
     
  4. El Sea
    Joined: Aug 2006
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    El Sea Junior Member

    Commercial vessels have height requirements that exceed recreational.
     
  5. dreamer
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    dreamer Soñadora

    hence my clarification that this is a private (recreational) craft.
     
  6. Landlubber
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    Landlubber Senior Member

    YA (Yachting Association), and in Australia, the AYA, have heights specified, if you ask that question someone will answer, unfortunately i am in China still, so camnnot check my books at home.
     
  7. dreamer
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    dreamer Soñadora

    Thanks Landlubber. I'll check that out.
     
  8. rasorinc
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    rasorinc Senior Member

    If it is riged then 36" is good because it is above the average hip line. If it is soft, (rope) then you want 3 lines.
     
  9. dreamer
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    dreamer Soñadora

    there is the aesthetic concern as well. I agree that 36" is a good height. Unfortunately, aesthetics do play an important part and on boats in the 40' range, 36" lines can look awkward (as can 3 lines).

    What would an absolute minimum be and still be considered a 'life' line vs. a 'trip' line.

    One raceboat I crewed on specifically said to NOT hold on to the lifelines. I only crewed on that boat once.
     
  10. Greybarn
    Joined: Apr 2006
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    Greybarn Junior Member

    For the boats we build, we use a few different heights that are dependent upon the LOA. For small boats, we use 24" from the deck to the top lifeline. For medium size boats, we raise that 27". For large boats (say 70 to 100) we use 30".
    Not sure what size boat you are putting these on, but I think that if you use 36" for the height then it will look out of proportion to the size.
     
  11. daiquiri
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    Location: Italy (Garda Lake) and Croatia (Istria)

    daiquiri Engineering and Design

    I should check it out but I recall through the mist that 60 cm (24") is a minimum for CE yachts.
     
  12. Steve W
    Joined: Jul 2004
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    Steve W Senior Member

    Most sailboat stanchions on the market are 24",if you want longer ones you need to special order them so i would say that was the norm,that said im replacing mine on a 26 ft boat with 28" ones. I wouldnt worry about 36" lifelines on a 40ft boat looking dorky,a friend of mine put them on a 37 and they look fine.
    Steve.
     
  13. Tcubed
    Joined: Sep 2008
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    Tcubed Boat Designer

    I will no doubt get some flak by posting here something i had previously written, due to the lifeline orthodoxy. Before attacking me please read carefully.
    My approach is solid bulwarks or none at all, never lifelines. And all smaller boats fitted with gorilla proof grabrails end to end. If sailing alone further than a few miles offshore the fact is ; fall overboard and die.
    The last time i sailed across the atlantic it was in a 22 footer and i had removed the lifelines and pulpit altogether. I installed heavy duty grabrails throughout. An acute sense of danger reminded me to hang on at all times. Even if you have lifelines you always must hang on so why have something that might fool you into a false sense of security?

    <<<<<<<There has been extensive research done on the phenomenon of risk compensation and it is fairly well accepted and understood that devices and systems that tend to promote safety encourages users to correspondingly behave less safely. A slight extension of the phenomenon is known as risk homeostasis. Risk compensation/homeostasis information is widely available from a number of sources. Probably one of the best known examples was when Sweden switched from driving on the left side of the road to the right side of the road. The month in which the switch was done had a record breaking low in road accidents and injuries and fatalities. The event was well anticipated by the public by extensive public announcements and so the perceived danger became larger than the actual danger, prompting excess caution from motorists.

    Indeed, the ratio of perceived/real danger is the underlining conclusion of the whole phenomenon. So for a safety system to be effective in practice, it must achieve a safety benefit which is greater than the perceived safety benefit.

    My personal view is that lifelines achieve the opposite effect and that the perceived safety benefits are greater than the real safety advantage. By creating a visual barrier they create a strong impression of being contained or shielded from the sea and dramatically reduce the sense of the danger of going overboard, thus promoting careless behaviour onboard such as standing up whilst underway or moving around the boat without adequately moving from one secure handhold to the next. Nevertheless, in the event of a man losing his grip/falling across the deck, lifelines are not as secure as they appear to be and in many cases fail under the impact load. Additionally, a person can easily slide between the lines or simply trip over them.

    There is no doubt that the lifelines are more of safeguard than having nothing there at all but that is not my point. My point is that their benefit is unfortunately outweighed by their overly powerful visual reference effect, creating perceived benefits which are too great, thus negating the original purpose of them.

    I know that i for one, have caught myself moving around boats with lifelines in uncharacteristically careless ways, compared to when sailing on my own boats, which do not have lifelines.

    The fact that they can't be all that strong is demonstrated to me everytime i have grabbed onto the lifeline to haul myself onboard a yacht for a visit, and get cautioned not to.

    Furthermore, i very nearly drowned as a boy by slipping through the lifelines of a friends boat, while on a little daysail.

    Racers object to them because they interfere with the sails and prevent crew from hiking correctly, or at least comfortably.

    Lastly, but this is very much beside the point, they are hideous!>>>>>>>
     
  14. marshmat
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    marshmat Senior Member

    It is worth noting that most of the smaller Coast Guard boats around here have beefy welded handrails everywhere, and anyone on deck is always within easy reach of at least two harness hardpoints, but there are no lifelines....
     

  15. dreamer
    Joined: Nov 2004
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    dreamer Soñadora

    TTT

    I like it. You won't get any flame from me.

    Except I will disagree that they look hideous. They can be designed to be an aesthetic extension of the vessel.

    OTOH, they CAN look hideous on certain vessels. Take a classic Herreschof or S & S and lifelines just will not do.

    In this particular case, these are for a trawler-yacht that has 24" deep bulwarks. The railing will be more for a decent place to rest an elbow while on passage.
     
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