[Public-List] Life lines

Bill Wallace via Public-List public-list at lists.alberg30.org
Wed Jul 9 11:26:19 PDT 2014


Just geometry along gives you a multiplier of between 2-6 : 1, and shock loading gives you another 2-5:1, so worst case you can reach 30:1 compared to weight, eg for 100 lbs for the person you could reach 3000 lbs force applied.  Those ratios depend a lot on how long each leg is and how much it is allowed to stretch, and how far you can fall, but say a 12' base and 1' stretch in the direction of fall would give you 6:1 from geometry, so no less than 600 lbs applied to each end just on the weight alone, no shock loading.


On Wednesday, July 9, 2014 2:12:07 PM, Lawrence Morris via Public-List <public-list at lists.alberg30.org> wrote:
 


And yes these standards have reams of studies to fall back on.



Larry 

Sent from my iPad

> On Jul 9, 2014, at 1:51 PM, Glenn Brooks via Public-List <public-list at lists.alberg30.org> wrote:
> 
> I think Gordon is saying that one should never trust the lifeline, not that they are inherently unsafe.   should some part of the lifeline , stanchion, etc, let go, then whomever is hanging on  at that point is seriously compromised, like my friend John.  
> 
> I do take one exception to the whole safety at sea regulatory thing, which perhaps someone on the list  can explain- the 4500 # breaking strength for jack lines and attachment points.  Most, if not all the West Coast racing rules require 4500 lb breaking strength for clip on points, and the webbing and jack lines that attach to one's harness.  Yet, it's hard to impossible to find deck eyes etc for small boats (30' ers like the alberg) in this size;  2500 -3500# are much more common.  And those 4500 fittings are massive and expensive.   More suitable to a 60footer!
> 
> Anybody know where this requirement came from and if there are actual engineering studies t0 support the requirement?  Or is this just another case where a bunch of type A rules committee  Old Salts doubled the old requirement For Safety By Gawd, not realizing their predecessors doubled the same requirement 20 years ago?  I would love it, if there is actually a reason for the requirement. 
> 
> Thanks
> Glenn B
> dolce 318
> 
> Sent from my iPad
> 
>> On Jul 9, 2014, at 9:26 AM, "Meinhold, Mike J. via Public-List" <public-list at lists.alberg30.org> wrote:
>> 
>> George and Mike
>> Good points on the failure mode analysis - don't want a single point of failure to drown you! It's my favorite position when the boat is heeled to the rail so I will have to look hard at the pelican hooks.  
>> I am not sure about Gord's opinion that the lifelines are not safe to lean on. If they cannot take the static load of my back at 25 degrees of heel, then they can't take the shock load when you grab them in the center as you fall overboard.  If they can't do that then they should not be there at all.
>> 
>> While the Chesapeake is not the Atlantic, as a frequent single hander I know the chain-of-failure processes that can put you at real risk out there, and respect them.
>> 
>> Mike
>> 
>> -----Original Message-----
>> From: Public-List [mailto:public-list-bounces at lists.alberg30.org] On Behalf Of Mike Lehman via Public-List
>> Sent: Wednesday, July 09, 2014 10:05 AM
>> To: Gordon Laco; Alberg 30 Public List -- open to all
>> Subject: Re: [Public-List] Life lines
>> 
>> I too nearly went overboard when the hinge pin on the pelican broke. I was sitting on the low side with the rail in the water when it let go...it was all I could do to stay aboard. I got rid of the pelican hooks after that.
>> 
>> 
>> 
>> 
>> ~~~_/)_/)~~ Mike Lehman ~~_/)~~~
>> 
>> 
>> -----Original Message-----
>> From: Gordon Laco via Public-List
>> Sent: Wednesday, July 09, 2014 9:58 AM
>> To: Wes Gardner ; Alberg 30 Public List -- open to all
>> Cc: George Dinwiddie
>> Subject: Re: [Public-List] Life lines
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