Winch Tolerance To Chain Size

[Dave22q]

i have an old horizon 900 winch which may need replacing. my chain measures 3/8 and i had no problems on several uses last year. lewmar support tells me the winch was sized for 5/16, 3/8 gipsy was not an option.
how tolerant are these winches anyway? is that 1/16 critical or is it just that i occassionally might have to to clear a jam? is clearing a jam as simple as reversing or a big deal?

[skipmac]

Originally Posted by Dave22q

i have an old horizon 900 winch which may need replacing. my chain measures 3/8 and i had no problems on several uses last year. lewmar support tells me the winch was sized for 5/16, 3/8 gipsy was not an option.
how tolerant are these winches anyway? is that 1/16 critical or is it just that i occassionally might have to to clear a jam? is clearing a jam as simple as reversing or a big deal?

First, it is not just the size of the chain which is a measure of the diameter of the steel making the link but also the size and shape of the link. Some 3/8" chain has longer links or even wider links but are still made of 3/8" steel.

So if your 3/8" chain has similar number of links per foot as the type of 5/16" chain the gypsy is designed to handle then you can probably get away with it, as you have seen.

[noelex 77]

Most unfortunately are reasonably specific, but it depends on the design of gypsy.

Take the gypsy off and wrap the chain around it and see how it lays.

The biggest danger is the chain can jump off the gypsy and it can develop quite a speed as it drops if the water is deep. Make sure know one tries to grab it if this happens.

[GordMay]

The gypsy/wildcat/chainwheel on your windlass is sized to fit one specific size & type (calibration*) of chain.

* Calibrated chain is chain that is made to internationally accepted standard dimensions with close tolerances. The two common specifications are DIN 766 Calibrated Chain, and ISO Calibrated Chain. The difference between the two specifications can be 2mm or more on the inside pitch of the link for the same diameter chain, which over several links (if the wrong chain was fitted) would cause the chain to jam or jump out of the gypsy.