Dock Line Calculator

Work out the right dock lines for your boat in seconds. Enter your vessel length and Dock Line Calculator gives you the recommended length for bow, stern and spring lines, plus the rope diameter to buy — in both inches and millimetres. FREE - Bow and stern line length - Spring line length - Recommended rope diameter - Heavy weather diameter for storm moorings - Feet or metres - One saved vessel PRO — one-time purchase, no subscription - Unlimited saved vessels - Snubber length from your bow freeboard - Anchor and mooring bridle leg length from your beam - Full line inventory with quantities and total rope needed HOW IT WORKS Bow and stern lines run about two thirds of vessel length, spring lines about the full length, and diameter follows the familiar one eighth of an inch for every nine feet. Everything is shown with the reasoning, so you can adjust for your own berth. Works entirely offline. No account, no sign-up, no data collection. Dock Line Calculator provides general guidance for recreational vessels and is not a substitute for manufacturer specifications or your own judgement as skipper.