Chain

Gumpy

Gumpy

Well-Known Member
Joined
12 Dec 2006
Messages
1,577
Location
A far corner of Little England
Visit site
I feel the need to upgrade my anchor chain to 8mm...
Now I have some 20m lengths of 5/16 chain that have come from chain hoists at work, this is not galvanised and at present is not rusty.
Is it worth using and then discarding each year, or will it rust into a ball after the first time I use it?
 
Depends if you want a rust coloured (or at least streaked ) boat. Look at any steel exposed to salt water.
 
If you have problems with the chain not being heavy enough, try a lead weight part way down. If the weight is slightly less than 1xdepth from the boat, so that it never quite reaches the seabed, it will add a lot o 'spring' equivalent to a much heavier chain.
Of course you don't say what your existing chain is...
Sell your plain chain for small boat mooring risers perhaps?
 
I have 6mm at present so will stick with that. I just have to get used to lighter things....... /forums/images/graemlins/blush.gif
On the Barge things need to be so much heavier ....... /forums/images/graemlins/frown.gif
 
[ QUOTE ]
If you have problems with the chain not being heavy enough, try a lead weight part way down. If the weight is slightly less than 1xdepth from the boat, so that it never quite reaches the seabed, it will add a lot o 'spring' equivalent to a much heavier chain.


[/ QUOTE ]

INTERESTING THEORY!!

Can you please develop it? what mathematic formula? which publicated tests??

Thanking you beforehand

João
 
[ QUOTE ]
Anchor "Chum"

Here

[/ QUOTE ]

Hi Sailorman,

My question was not who is advertising for a « marketing Gadget product »

Yes, I perfectly know the « compass » chum, as well as the « Mobilest » « Anchor Buddy » from New Zealand.. as well as kellet, sentinel, angel…

Mathematics says that a kellet is the most effective to increase holding, as close as possible to the anchor shank – not « <span style="color:blue"> slightly less than 1xdepth from the boat </span> »

Mathematics ( catenary formula) says that a kellet has a negligible efficiency...

If you have a different theory, I will be very pleased to learn it – but please give me all your proofs – mathematic formulas – comparative tests???....

Thanking you beforehand..

João
 
[ QUOTE ]
personally i dont need to prove anything .
if you want / req info, you find & trust it.

[/ QUOTE ]

Thanks Sailorman for your answer..

But, like you I don't want / req. info.. as, since a long time, I have all of them /forums/images/graemlins/wink.gif
 
[ QUOTE ]
I feel the need to upgrade my anchor chain to 8mm...
Now I have some 20m lengths of 5/16 chain that have come from chain hoists at work, this is not galvanised and at present is not rusty.
Is it worth using and then discarding each year, or will it rust into a ball after the first time I use it?

[/ QUOTE ]
Which part of the chain hoist? The actual lifting chain or the chain you pull on to operate the lifting chain.
If it is the actual lifting chain then I see no reason why you can't use it as an anchor chain. It will be either grade 80 or grade 100 chain which is far stronger than the grade 40 usually used for small boat anchor chain.
Grade 80 and grade 100 are both 'alloy chains' which means the steel is mixed with other metals such as nickel and either chromium or molybdenum to harden and prevent corrosion, like stainless steel chain. And stainless steel chain is used on small boats as anchor chain.
When I use to work on Diving support and pipe laying vessels, we use to place structures on the seabed for sub sea storage, sometimes using grade 80 and grade 100 chain sling. Then weeks later we would recover to deck to take the structures to their final working position.
So I think if a lifting chain can under go that type of punishment it can handle being an anchor chain on a 7.5m yacht.
It will not need to be galvanised because it has all the alloys that a stainless steel chain has (admittedly not in the same quantities, but you say you will be changing it out every year).
Someone might contradict this, but if I had that chain to hand, I would use it. I think the only reason you don't see grade 80 chain as anchor chain is because it is expensive.
 
Its actually the lifting chain from a Lodestar electric hoist. 5/16" rated lift 1 ton and we proof test them to 1.25 ton, so the breaking strain will be well above this, in fact you could lift the boat with it /forums/images/graemlins/wink.gif
As for the Alloy content, that explains why having used some of it as a stern anchor chain on the barge, mainly in fresh water, it never showed the slightest sign of rust (although it was kept in a bucket and dowsed with WD40).
I think I will cut the rusty end off the 6mm and and see how I get on for now but keep the other chain in reserve.
 
A bit of misinformation above. The nickel and chromium content of Grades 80 and 100 chain are about 0.5 - 1.0 %, possibly with around the same of molybdenum although this may only apply in USA. The chromium content would need to be 18% for good corrosion resistance, although 400 grades with 13% are fairly good in seawater.

Some of these grades have a coating, not entirely corrosion resistant but giving some protection.
 
Too many years ago I worked for a company called George Kings in Stevenage who used to make electric chain hoists. I used to get the old chains from when the hoists were reconditioned and join lengths together and get it galvanized for use on my boat.

So I think it is a great idea.

Some people on this fora did think the galvanizing would weaken the chain but I never had any problem.
 
You must log in or register to reply here.

Share this page

Top