Iso 10P30 (3/8) chain compatibility with 10mm anchor chain

[Etesian]

We have a Lofrans windlass marked Iso 10 P30 (3/8 HT). We assume that this is the chain installed by the manufacturer and currently on the boat.

We want to add an additional length of chain to our existing chain however, here in Marmaris Turkey, we are unable to locate a source for Iso 10 P30 (3/8 HT). We have located DIN766 10mm chain with the same link length (50mm).

Is the DIN766 10mm chain compatible with our existing Iso 10 P30 (3/8 HT) chain?

 

[vyv_cox]

We have a Lofrans windlass marked Iso 10 P30 (3/8 HT). We assume that this is the chain installed by the manufacturer and currently on the boat.

We want to add an additional length of chain to our existing chain however, here in Marmaris Turkey, we are unable to locate a source for Iso 10 P30 (3/8 HT). We have located DIN766 10mm chain with the same link length (50mm).

Is the DIN766 10mm chain compatible with our existing Iso 10 P30 (3/8 HT) chain?

Take the gypsy off the windlass and try it against the chain you are thinking of buying. There is a good chance that it will fit.

When I replaced my 5/16"chain with 8 mm I bought an 8 mm gypsy beforehand to replace the existing 5/16" one. But just for fun I tried the 8 mm chain with the 5/16" gypsy, and of course it ran perfectly well.

 

[Salty John]

You can get Din 766 10 x 48 x 34 (width of link) and you can get calibrated 10 x 50 x 35. I understand that the former will not run on a Lofrans gypsy whilst the latter will. I only point this out to indicate that small differences can have a significant effect.

Do as Vyv says and take the gypsy to the chain. There is nothing worse than chain skipping on the gypsy because it's a slight mismatch. 3/8" is 9.52mm so you are asking a 10mm chain to run on a smaller gypsy and relying on the slop factor to allow this. Could be an expensive mistake.

Switching from 5/16" imperial to 8mm is not so tricky because there is only 0.003mm difference in link length between the two. Unless my maths is hopelessly out!

 

[Salty John]

Actually, American 3/8"HT has a link diameter of 13/32" or .403" which is a tad over 10mm. It would seem the gypsy is designed to run both sizes. American chain always has a link diameter slightly more than the nominal size.

 

[Etesian]

Thanks for your input

We took the gypsy with us and the 10mm (50) seemed to fit so be purchased 35 meters, attached it to our existing chain and it seems to be fine. We've run it through (up and down) the windlass a few times and did not encounter any snags or problems. Whew !!!

 

[vyv_cox]

C-links

We took the gypsy with us and the 10mm (50) seemed to fit so be purchased 35 meters, attached it to our existing chain and it seems to be fine. We've run it through (up and down) the windlass a few times and did not encounter any snags or problems. Whew !!!

How have you attached it? You need to be very careful with C-links. Although the good ones, made for hoisting applications, are virtually as strong as the chain, many others sold by chandlers are utter junk. See my website for more information.

 

[Talbot]

Jimmy Green now sells both the din and the ISO versions of the 10mm chain.. Apparently there is a significant difference in the length of the link. The wrong one can promote chain jumping under load around the gypsy - not recommended. Seen it once on a big ship where the initial jump was caused by a high snatch load. Not pretty.

 

[Bilgediver]

We have a Lofrans windlass marked Iso 10 P30 (3/8 HT). We assume that this is the chain installed by the manufacturer and currently on the boat.

We want to add an additional length of chain to our existing chain however, here in Marmaris Turkey, we are unable to locate a source for Iso 10 P30 (3/8 HT). We have located DIN766 10mm chain with the same link length (50mm).

Is the DIN766 10mm chain compatible with our existing Iso 10 P30 (3/8 HT) chain?

When measuring chain for comparison do not measure just a single link. It is usual to measure over five links and this then makes it easier to compare if one chain is compatible with another. Like wise measure when new and log and then measure from time to time. Too much change in the 5 link length will possible result in gypsy jamming

 

[chainman]

ISO and DIN chains

10mm or 3/8" chain generally comes in two pitches. ISO chain has a 30mm pitch and DIN 766 has a 28mm pitch. We have found that generally they won't fit the same gypsy. They might run for a while but will jump.
We have joined old chain to new chain with a calibrated and tested welded joining link as we have found split links to be of poor quality.However Certex/Crosby do riveted split links which are good ones but you have to be sure they are joined well and that the pitch matches your gypsy.
Lewmar, Lofrans, Quick, do gypsys for both pitches so be careful that you get the right pitch to match your gypsy.
Check out my website for chain details www.bradneychain.com or drop me a line
chris@bradneychain.co.uk
Regards
Chainman!

 

[Pleiades]

working on the chain gang......

Have a Lofrans Airon windlass which was running 3/8th" chain and wanted to replace it with new length. Wondered if 10mm might work. Contacted Lofrans and their technical relpy was "it might, try it and see." That would seem a resonable approach - buy a few metres and run it against some load to see what happens. I eventually bought 120m of 10mm and it works absolutely perfectly on my windlass - can't remember the model number. A possible alterrnative is to buy a new plate for the top of your windlass if Lofrans will supply one calibrated for 10mm. I would not however recommend joining chain - the c links mentioned above are in my opinion too much of a potential weak link and if it is going to jam or hang up on the windlass it will probably be at the join. Better to keep the old 3/8th chain for a kedge or second main or for emergency use and splash out on a new length of 10 mm if you can find it locally at the right price and quality.

Hope it does the job for you anyway when the wind blows a hooligan. Pleiades spent last Friday evening hooked comfortably to the seabed (mud) in Force 8/9, swinging on 70 metres of 10mm with two nylon spring lines on a 20kg Delta - no snatch and did not budge an inch. Very comfy although the windmill lost the plot somewhat!

Happy hooking,
Robin
Pleiades of Birdham
MXWQ5