Anchor Chain

[Panama Red]

What is the practical difference between G3 and G4 chain?

I have a short G3 and I want to replace with much longer G4. Will G4 fit a windlass that has been used with G3?

Do I drag the chain from the shop to the boat, or take the windlass to the shop to see if it will work?

Don’t laugh because I have been there before, but can G3 chain replace G3 chain?

[robinco]

Could you modify your last sentence perhaps?

[NYSail]

Buy 3 feet and see if it fits. Or called the windlass maker and ask.

[Jim Cate]

Take the gypsy off and carry it to the chain vendor... easy peasy.

Jim

[noelex 77]

For metric chain, G3 and G4 chain has the same dimensions. For imperial chain, G30 and G43 have different dimensions. So with imperial chain you will often need a new gypsy (and they are not cheap) when switching, but with metric chain there is no change. However, even with metric chain there are still traps for the unwary. For example there are two different and equally common sizes of 10mm chain available.

Taking your gypsy to the chandlery is always good advice. Some gypsies are tolerant of a range of chain sizes and others are very specific.

Finally, the difference in strength between G30 and G40 is not great. G40 uses a lower safety factor for the SWL which artificially inflates the differences. In addition, a reasonable amount of G30 specified chain seems to made from G40 when tested. The speculation is that G40 steel suitable for chain making is more readily available than G30, so often the higher grade is used and sold as G30 and G40 at different price points. I have no idea if this accurate.

G70 chain is also available. G70 is significantly stronger so often one chain size smaller G70 will have the same strength as thicker (and therfore heavier) G30 chain. However, chain durability does seem to suffer if the chain size is reduced so more frequent replacment is likely to be needed which together with a new gypsy can make it a costly conversion.

This link provides some great information on chain dimensions:

Chain – Cox Engineering

[fxykty]

At worst, you will need a new gypsy. Likely a lot less expensive than the chain.

[double u]

found several times that neither trying a short length of chain nor taking the gypsy in guaranteed a fit: under no load it is easy to fit a chain that will start jumping on the gypsy after 10cm when taking up under load. Had one customer return 100m of 10mm stainless chain that was jumping. He had his gypsy with him & in the warehouse we ran the whole length over it without a hitch. Measuring all the links of the offending section (right in the middle, of couse...) that he had marked we found links that were more than 2mm longer.
Test in the shop will only be meaningful if you can apply a goodly load, pulling the chain over the gypsy by hand will at the most prevent you from a 8 to 10mm mismatch

[kas_1611]

Originally Posted by noelex 77

For metric chain, G3 and G4 chain has the same dimensions. For imperial chain, G30 and G43 have different dimensions. So with imperial chain you will often need a new gypsy (and they are not cheap) when switching, but with metric chain there is no change. However, even with metric chain there are still traps for the unwary. For example there are two different and equally common sizes of 10mm chain available.

Taking your gypsy to the chandlery is always good advice. Some gypsies are tolerant of a range of chain sizes and others are very specific.

Finally, the difference in strength between G30 and G40 is not great. G40 uses a lower safety factor for the SWL which artificially inflates the differences. In addition, a reasonable amount of G30 specified chain seems to made from G40 when tested. The speculation is that G40 steel suitable for chain making is more readily available than G30, so often the higher grade is used and sold as G30 and G40 at different price points. I have no idea if this accurate.

G70 chain is also available. G70 is significantly stronger so often one chain size smaller G70 will have the same strength as thicker (and therfore heavier) G30 chain. However, chain durability does seem to suffer if the chain size is reduced so more frequent replacment is likely to be needed which together with a new gypsy can make it a costly conversion.

This link provides some great information on chain dimensions:

Chain – Cox Engineering

As Noelex says there is no difference in metric chain as I swapped my "ungraded" 8mm for G70 8mm with no problems a couple of years ago. The main thing to look for is the DIN or ISO numbers (maybe stamped into a link). I didn't want to have to mess around changing the gypsy but wanted strong chain hence the 8mm G70.