Most anchoring headaches don't begin at the anchor—they begin at the gypsy. A rode that doesn't match your windlass can skip under load, jam on retrieval, wear the gypsy prematurely, or refuse to pass the rope-to-chain splice smoothly. And it almost always traces back to one mistake: assuming chain diameter alone determines compatibility. It doesn't.
Your windlass gypsy (the toothed wheel that grips the chain) is machined with pockets shaped for one specific link geometry. Two chains can share the same nominal size—“5/16 inch” or “8 mm”—yet have different link length, width, and wire diameter depending on the manufacturing standard. Get the standard right and any quality windlass hauls smoothly. Get it wrong and the chain rides high on the teeth, skips, and wears out both the chain and the chainwheel early.
This guide walks you through how to match all three pieces—gypsy, chain, and rope—so your ground tackle works the first time and every time.
Why chain standard matters more than diameter
When you buy “1/4-inch chain” or “5/16-inch chain,” that measurement refers only to the wire (link) diameter—the thickness of the metal the link is bent from. It tells you nothing about the pitch (inside link length) or width, and those are exactly what the gypsy pockets are cut to grip.
A gypsy cut for one standard will not correctly seat chain built to another, even at the same nominal size. Run the wrong standard and the chain doesn't drop cleanly into each pocket—it rides on the tips of the teeth, which means slipping, skipped links, and accelerated wear no matter how new or powerful the windlass is.
Bottom line: Always match the chain standard, not just the diameter.
Common chain standards at a glance
| Standard | Sizing | Typical range | Notes |
|---|---|---|---|
| DIN 766 | Metric (mm) | 6–16 mm | Calibrated short-link chain; the most common fit for European metric windlass gypsies. |
| ISO 4565 | Metric (mm) | 6–12 mm | Metric calibrated chain with a slightly different pitch/width than DIN 766 at the same nominal size. |
| ACCO ISO G43 (G4 / G40 / HT) | Imperial (in) | 1/4″–1/2″ | High-test grade with a longer link pitch; standard on most new US-market windlasses. |
| ACCO BBB (3B) | Imperial (in) | 1/4″ and up | Short-pitch imperial chain found on many older US windlass gypsies. |
HT / G4 vs. BBB — they are NOT interchangeable. “HT,” “G4,” “G40,” and “G43” all refer to the same high-test chain and work interchangeably with each other. BBB chain has different link dimensions and a shorter pitch. A gypsy cut for 5/16″ G4 will often skip 5/16″ BBB, and vice-versa. Almost all new windlasses require HT/G43 chain. Always confirm against your windlass manual before you buy.
Rope & chain pairing chart (combination rode)
A combination rode—nylon rope spliced to a chain leader—is the most popular setup for recreational powerboats and cruisers. It's lighter, easier on the windlass and anchor locker, and the nylon adds shock-absorbing stretch. As a rule of thumb, windlass rope runs roughly twice the chain's diameter, but always confirm against your gypsy's rope groove.
| Chain size | Common chain standard | Typical paired 3-strand nylon rope | Good for |
|---|---|---|---|
| 1/4″ (6–7 mm) | G4 / HT, BBB, DIN 766 | 1/2″ (12 mm) | Boats to ~28 ft |
| 5/16″ (8 mm) | G4 / HT, BBB, DIN 766 | 9/16″ (14 mm) | 28–38 ft |
| 3/8″ (10 mm) | G4 / HT, BBB, DIN 766 | 5/8″ (16 mm) | 40 ft and up |
Rope type: Most windlass makers recommend a premium, windlass-grade, medium-lay 3-strand nylon or a multi-plait nylon rode. The consistent lay is what lets the splice feed cleanly through the gypsy without hanging up.
Chain link geometry: the D, P & W measurements
If your gypsy isn't marked, or you're replacing existing chain, measure a single link and match all three dimensions to the standard below:
- D — wire diameter: thickness of the metal the link is made from
- P — pitch: inside length of a single link
- W — width: inside width of a single link
| Chain model | D (mm / in) | P (mm / in) | W (mm / in) |
|---|---|---|---|
| 1/4″ ACCO BBB (3B) | 7.14 / 0.28 | 22.10 / 0.87 | 25.20 / 0.99 |
| 1/4″ ACCO G43 (G4) | 7.00 / 0.28 | 21.30 / 0.84 | 24.40 / 0.96 |
| 6 mm DIN 766 | 6.00 / 0.24 | 18.50 / 0.73 | 20.40 / 0.80 |
| 8 mm DIN 766 | 8.00 / 0.32 | 24.00 / 0.95 | 27.20 / 1.07 |
| 5/16″ ACCO G43 (G4) | 8.40 / 0.33 | 26.20 / 1.03 | 29.70 / 1.17 |
| 3/8″ ACCO G43 (G4) | 10.00 / 0.39 | 31.00 / 1.22 | 35.00 / 1.38 |
| 10 mm DIN 766 | 10.00 / 0.39 | 28.00 / 1.10 | 36.00 / 1.42 |
Two chains with the same nominal size can differ in P and W by a fraction of an inch—and that fraction is the difference between a gypsy that grips and one that skips.
How to identify what your windlass needs
- Find the make and model. Look on the windlass housing, inside the anchor locker, or in the owner's manual. Common brands include Lewmar, Maxwell, Quick, and Lofrans.
- Read the gypsy markings. Most gypsies are stamped with the chain size and standard they accept—for example, “5/16 G43” or “8 mm DIN 766.” This is the fastest way to confirm the correct chain.
- Confirm the chain diameter and standard against those markings or the manual—never diameter alone.
- Match the rope groove to the correct rope diameter and type.
- Match the splice. Make sure your rope-to-chain splice is compact enough to pass through the gypsy under load without hanging up.
A quick word on sizing the windlass itself
Before matching the rode, make sure the windlass is right for the boat. Add up the weight of your anchor, all chain, and rope—that total should stay under the windlass's maximum working load, and the total × 3 should stay under its maximum pull. For a 32–38 ft boat that usually points to a 600–700 lb working-load windlass. Sizing up one class is advice you'll never regret. For the full method, see our companion guide, How to Choose and Size an Anchor Windlass.
Shop the matching gear at Go2Marine
- Anchor chain — G4/HT, BBB, and 316 stainless, calibrated for smooth gypsy operation
- Anchor lines & rodes — 3-strand and double-braid nylon, pre-spliced options
- Lewmar anchor windlasses — units, gypsies, and parts
- Anchoring & mooring hardware — shackles, swivels, and connectors
Compatibility checklist (save this before you order)
- Windlass make and model confirmed
- Gypsy markings read (size and standard)
- Chain standard matched — G4/HT vs. BBB vs. DIN 766 vs. ISO 4565
- Chain diameter confirmed against the gypsy
- Rope diameter and type matched to the rope groove
- Rope-to-chain splice sized to pass the gypsy cleanly
Not sure what your gypsy accepts? Send us your windlass make, model, and a photo of the gypsy markings, and the Go2Marine team will confirm the exact chain, rope, and parts you need.