mooring shackles & Gal. chain

I think the name of the game is eliminating peak dynamic loads out of the system for a low wear and a long life. This means introducing as much as elasticity in the system as possible.

Check http://www.hazelettmarine.com/ You may talk to Jeff Lefebvre there for advice.

Cheers.

 

General Manager

Michael,

we have studied mooring design for over 20 years and have come to the conclusion that chain can work good in a protected site with good water characteristics. Other than these conditions, local knowlwdge is very important along with lots of luck.
We have eliminated chain in any of our systems because it does not have any properties for longevity nor does it develop proper holding forces in winds over 40-mph.
the Hazelett Marine elastic moorings will fit any boat application and have only one or two moving parts to wear out. Our elastic mooring system will outlast chain by 5 times and produce more than adequate holding forces in 70-mph wind and wave conditions. We can discuss this futher if you care to download the "Chain VS Elastic" report from our website. It is long, boring but, absolutly correct. The test were done under the supervision of a Yale professor of physics.
We are involved with some major anchoring projects around the world and gain more knowledge from every new client. Hope to hear from several of the prople in this thread.

 

Thanks Jeff,
I'll take a look.
I am a little hampered in that I am obliged to use approved mooring contractors to make and place my mooring.
It partly has to do with insurance for my boat and also meeting the current requirements of Parks Victoria the controlling body for our bays.

Mike

 

NOAA here in the USA is giving a presentation on consevation mooring technology. We designed our systems for security and longevity. the conservation engineering came with it. Sometimes you have to ride a different horse to get to the same place, security.

 

Jeff
As a student of engineering I can see a few problems

This report is very amateurish and looks more like glossy advertising than any attempt at either a physics or engineering analysis of a mooring system.

Who was this yale professor of physics? I find this very hard to believe.

He has stuffed up a bit too since all your actual in use static chain catenary forces will be out by nearly 13% since he has apparently forgotten a very important principle. Also Inertia doesn't change in a system, you actually mean momentum.

You also don't consider either energy or a proper dynamic analysis nor do you consider that the vessel reacts in complex ways to the bollard pull.

Dampers in the way of lengths of extra heavy chain and pigs have been added to chain moorings and anchoring systems for a very long time, thin nylon and rubber snubbers are often used in parallel to chain and then you still get a lot of extra insurance.

Elastic systems may even store more energy in the system and produce a higher bollard pull for far longer particularly if stretched to the limit, you should analyze that too. You can decrease the shock load in a variety of ways but you need to look very carefully at the whole dynamics picture and that is sadly lacking here.

Trying to apply a static observation to a dynamic system and then using the numbers to justify an argument is neither physics nor engineering I'm sorry to say and it is naive and very unprofessional to base assumptions on such an analysis. Even then the developed models will need to be adjusted with real world data.

Nice try but.