Which Gypsy Fits My Muir Windlass?

Fitting the wrong chain to a windlass gypsy is the most common anchoring mistake we see from US boat owners. The chain looks right, drops into the wheel — then jumps or slips under load, exactly when you need it most.

The basics

Why the gypsy must match the chain exactly

A windlass gypsy (Americans often say “chain wheel” or “wildcat”) is a cast wheel with pockets shaped for one specific chain: one wire diameter, one link pitch (the inside length of each link), one link width. When pockets and chain agree, every link seats fully and the windlass pulls on chain, not friction. When they don’t, links ride up on the pocket edges — the chain skips under load, dumps the anchor in gusts, and chews up both gypsy and chain.

The #1 US trap

BBB vs G4 — same label, different chain

Both are sold as “5/16″ windlass chain”. They are not the same chain:

Factory figures from Muir’s engineering data.

A ~0.8 mm pitch difference per link accumulates to more than 2″ of error over ten links — far beyond what a gypsy pocket tolerates. A BBB gypsy will not run G4 chain reliably, and vice versa. And because Muir windlasses are built in Australia, a unit that crossed with the boat may be wearing an ASL gypsy that matches nothing on your chandler’s shelf. The cure is never “close enough” chain — it’s the correct gypsy, a straightforward bolt-off, bolt-on part.

Diagnosis

Identify what you have in three steps

1. Find your windlass model. On the housing badge or the motor label below deck — e.g. HR1600 Cougar, Storm VR/VRC 1250.
2. Read the gypsy itself. Muir gypsies carry a cast identification number on the wheel face or hub. Note it down — it identifies the exact pattern when ordering a replacement.
3. Measure your chain. Calipers on the wire diameter (8 mm ≈ 5/16″), then measure the inside length of ten links pulled tight and divide by ten for true pitch. Pitch — not diameter — is what separates BBB from G4.

The full matrix

Muir gypsy availability by model & chain standard

Every combination below has a factory gypsy available, straight from Muir’s engineering data:

“—” = no factory gypsy for that combination; ask us about the nearest supported chain. ISO 4565 and stud-link options exist for some models.

Seated right vs. slipping

Drop a metre of chain into the gypsy by hand and look side-on: every link should sit fully down in its pocket, vertical links passing cleanly through the stripper. Links perching on pocket edges or riding up as the wheel turns mean the pitch is wrong — under power that becomes the tell-tale clack-clack-slip of a jumping chain.

Upgrading the whole windlass instead? See the 30–40 ft windlass guide or browse Muir windlasses.

Quick answers

Frequently asked questions