7mm anchor chain

[lindsay]

I have heard that a new 7mm grade 40 calibrated chain made by Maggi in Italy is just strong as an 8 mm chain, with an appreciable weight saving, and less effort for the 30 metres chain I currently have for a 28footer. I have a Simpson Lawrence manual wind!ess, "suitable for 6mm or 8 mm chain". Will the 7mm chain work without modification of the existing windless??

 

[ditchcrawler]

I had an electric windlass that I picked up cheaply because it was for 7mm chain only. The gipsy on a windlass is usually specifically for a size of calibrated chain and it is very unlikely that your current gipsy will work.

 

[VicMallows]

By amazing coincidence, this precise same question was asked on the Sadler and Starlight forum only 5 days ago. The answer was that the windlass could be used with either 6mm or 8mm chain by changing the gypsy. I am sure that you would need a different gypsy for 7mm. Whether such is available is a different matter.

 

[BobnLesley]

Does your anchor chain actually need renewing? If not, then I honestly think there are many better ways of spending a stack of beer tokens:
As has been noted by others already, I think it highly likely that this change would also require a change in your windlass gypsy - yet more beer tokens - and whilst the weight saving could be described as "appreciable" - it'll be just short of 25% - on a 30m chain that only actually equates to about 10kg in total.

 

[vyv_cox]

I have heard that a new 7mm grade 40 calibrated chain made by Maggi in Italy is just strong as an 8 mm chain.......

The UTS of Grade 40 7mm chain is 31 kn (3.1 tonnes) whereas the UTS of Grade 30 8mm chain is 30 kn (3.0 tonnes). These are the minimum values but most chandlery bought Grade 30 is slightly above the minimum, so you might as well say they are the same. The weight saving is 0.3 kg per metre, so your savings are not all that worthwhile, only 10 kg. Set against the cost of a new gypsy, hardly worth having. If you could find any Grade 70 6mm it might be more worthwhile but as Jonathan Neeves has found it is a very rare commodity.

All the chain data is on my website.

 

[Neeves]

Its difficult to see the point of a Grade 40 7mm chain when they make a 8mm G40 - except they have entered the American market and I would suspect they are making a metric chain out of their 1/4" wire (which is nominally 7mm). The savings in weight are not really significant though you also save in space in your chain locker. If 'towering' is an issue then maybe together the weight and space saving might make it interesting, particularly if you need new chain. Sadly gypsies cost an unreasonable amount of money and before doing anything I'd check that cost first. The windlass makers have a whole range of gypsies. Much to my surprise, I checked, Maxwell make gypsies to suit EN818 x 7mm and I think its a different gypsy to suit Din 766 x 7mm for a number of their windlass and I assume other windlass makers will have a similar range, particularly Lofrens and Quick.. I don't know but maybe a 1/4" gypsy will fit, and you might get one at a boat jumble?? (I checked my Muir gypsy only yesterday, we are using 8mm and the gypsy is marked 5/16" and we have not had any problems). You will also need to find shackles that fit the chain and fit your anchor (fit for size and strength) - its not quite as simple as it seems - but it is possible.

I have had 75m of G80 x 6mm specially processed, a one off, I had to source connectors to match and have them similarly processed (all at the same time). I'm just waiting for some follow up tests and if they confirm initial tests I'll install (replaces the 8mm mentioned above) on our catamaran. You need to have group of sympathetic suppliers and processors to get this to work - but its taken about 6 months of planning after some initial trials. If it works satisfactorily and, importantly, safely the full detail will all be available.

No-one makes a gal 6mm G70, the Americans make gal G70 x 1/4". So if you are using 8mm and fancy the idea of using a smaller but stronger chain (and are not too enamoured with catenary) then there is no real option currently as the savings, for 1/4'/7mm in weight and space are not too dramatic.

Jonathan

 

[vyv_cox]

Much to my surprise, I checked, Maxwell make gypsies to suit EN818 x 7mm and I think its a different gypsy to suit Din 766 x 7mm for a number of their windlass and I assume other windlass makers will have a similar range,

I was looking at the Maxwell info not all that long ago and was amazed to see how many gypsies they make. From memory at least 20 different chain sizes and grades. It brought home to me just how many different link dimensions there are for the same wire size. I was in an argument at the time about 'ISO' chain but there are several in each wire size: the exact spec needs to be given.