Lofrans Kobra windlass-chain size

[Moodyman]

I have a Lofrans Kobra windlass and the gypsy is marked 5/16in I want to replace the chain which is pretty rusty. Would 8mm calibrated chain be OK for the size of the gypsy? I have tried to measure the dia and pitch but I'm not sure of the accuracy.

 

[nigelmercier]

I'm guessing you will need a new gypsy for 8mm chain.

 

[rogerthebodger]

It not so much the chain wire dia but the link pitch and width.

When you go to buy the chain take the gypsy along with you to check the link pitch in the gypsy.

 

[GrahamM376]

It not so much the chain wire dia but the link pitch and width.

When you go to buy the chain take the gypsy along with you to check the link pitch in the gypsy.

+1

Could be ISO or DIN. Gypsy comes off easily and the new chain needs to fit snugly for a complete turn or it will jam.

 

[prv]

Could be ISO or DIN.

Surely if it's marked "5/16th" it's more likely to be some American standard (or very old)?

Pete

 

[vyv_cox]

You may get away with replacing 5/16 with 8 mm, but you may not. I had to buy a new gypsy for my Maxwell when I went that way. See my chain info at http://coxengineering.sharepoint.com/Pages/Chaindefinitions.aspx

 

[GrahamM376]

Surely if it's marked "5/16th" it's more likely to be some American standard (or very old)?

Pete

My previous chainwheel was marked 3/8" but 10mm ISO fitted OK. DIN chain didn't fit but on 10mm there's a big difference in link size between ISO & DIN.

 

[vyv_cox]

My previous chainwheel was marked 3/8" but 10mm ISO fitted OK. DIN chain didn't fit but on 10mm there's a big difference in link size between ISO & DIN.

As my recent YM article said (twice!!!!) the tolerance of the ISO standard is a lot bigger than the DIN. For 10 mm, as you say, the link length is 2 mm different between the two, but not for 8 mm. So the OP might be lucky, check the fit carefully before buying.

 

[Salty John]

Take the gypsy to the chain and be sure the chain fits, there are few things more miserable than a chain skipping or jamming in the windlass.
Regarding 5/16" US chain it should be noted that on all US short link chain wire gauge is 1/32" bigger than nominal. Thus, 5/16" is actually 11/32", or 8.7mm. The differences between 5/16" US and 8mm are greater than the differences between 3/8"US and 10mm; I doubt you'll get away with it on 8mm.

 

[Salty John]

Looking through notes, I see that 9 x 27 x 31 DIN 766 may fit 5/16" gypsies. Also a note that says 10mm DIN766 will not fit Lofrans, ISO may. Can't remember the source for this information.

 

[claymore]

My Lofrans Kobra fits 10mm calibrated chain

 

[Moodyman]

Thanks for all the advice. It has made me look again at the gypsy and I have found another stamp which says 8mm Din 766. I have measured the link diameter as accurately as I can which is very close to 8mm. Also the pitch measurement is around 25 mm and the inner dia around 10mm. Using the Cox engineering chain size info page the grade 40 8mm seems closest. Am I right in my thinking?

 

[vyv_cox]

Thanks for all the advice. It has made me look again at the gypsy and I have found another stamp which says 8mm Din 766. I have measured the link diameter as accurately as I can which is very close to 8mm. Also the pitch measurement is around 25 mm and the inner dia around 10mm. Using the Cox engineering chain size info page the grade 40 8mm seems closest. Am I right in my thinking?

Unfortunately it has been pointed out to me that there may be an error in the Grade 40 dimensions, specifically the 10.5 mm value for 'C', which should be as for Grade 30. I cannot correct it, or check against my records at home, until next week. Most of the chain you can buy at your local chandlery will be nominally Grade 30, although as my recent tests showed, many of them have the strength of Grade 40.

 

[GrahamM376]

Thanks for all the advice. It has made me look again at the gypsy and I have found another stamp which says 8mm Din 766. I have measured the link diameter as accurately as I can which is very close to 8mm. Also the pitch measurement is around 25 mm and the inner dia around 10mm. Using the Cox engineering chain size info page the grade 40 8mm seems closest. Am I right in my thinking?

Both DIN and ISO allow +/- tolerences so there may be a slight variation between links and another problem I've found with some chandlers is that the staff haven't a clue what spec of chain they're selling, they generally stock the one suited to the make of windlass they sell. Best take the gypsy with you to be safe.

 

[Moodyman]

Thanks again. I was recommended to go to Bradney Chain so I will contact them, rather than speak to my local chandlers who I suspect will not have the knowledge of a main supplier.

 

[KellysEye]

Bear in mind that calibrated chain has smaller link sizes than non-calibrated. If possible get a short piece of what you are thinking of buying to test it.

 

[vyv_cox]

Thanks again. I was recommended to go to Bradney Chain so I will contact them, rather than speak to my local chandlers who I suspect will not have the knowledge of a main supplier.

Good choice. Their chain did well in my recent tests and I know that they buy from one of the best chainmakers in the world (yes, in China)