Anchor Rode Sizing Calculator

Because the table strength is a new, dry, unknotted sample: real rode carries splices (−10–15%), wet nylon (−10–15%), age and UV, chafe you haven't found yet, and shock loads the steady design figure didn't include. Stack those and 4:1 on paper is closer to 1.5–2:1 in the gale — which is the margin actually keeping the boat. Working Load Limits printed on chain (typically break÷4) encode the same philosophy.

Strength per pound: high-test G4 breaks ~1.7× proof coil G3 of the same size, G7 transport chain higher still. The practical win is downsizing — 5/16 G4 outperforms 3/8 G3 while weighing 30% less — but mind the windlass: gypsies are cut for specific chain size AND grade calibration, and mixing leaves expensive aluminum confetti. Galvanizing quality matters more than grade for lifespan at anchor.

Stretch is the feature: nylon elongates 15–25% at working loads, absorbing surge energy that would otherwise arrive as shock — exactly what polyester (low stretch) and Dyneema (near-zero, floats, slippery on drums) can't offer at anchor. The same elasticity is why the snubber on an all-chain rig is always nylon. Three-strand splices easily and chafe-inspects visibly; brait stows better. Either way: oversize for chafe, the killer the strength table can't see.

The cruising hybrid: enough chain to stay on the bottom through normal swinging (one boat-length minimum; 30–60 ft typical coastal) spliced to nylon for the rest — chafe protection where the rode meets ground, weight savings everywhere else. Full-chain rodes earn their 400 lb on coral, rock and weed bottoms and with windlass handling; the calculator's weight line is there so the choice is made with open eyes.