#1 Boat Dock Line Length Guide for Bow, Stern, and Spring Lines
Calculate boat dock line length from LOA, slip layout, tide range, cleat spacing, wind exposure, and storm mode.
BLUF
A common starting point is bow and stern lines around two-thirds of boat length and spring lines around full boat length. Tide, cleat spacing, storm exposure, and transient docking can justify longer lines.
Dock line comparison
Why fixed rules are not enough
A floating dock in a sheltered lake is different from a tidal slip with wakes and wind. Use the calculator for a starting point, then fit the line to the actual cleat geometry.
Docking checklist
- Boat length overall
- Cleat positions
- Fixed or floating dock
- Tide range
- Wind and wake exposure
- Chafe protection
- Storm backup lines
FAQ
Should dock lines be tight?
They should control the boat without fighting normal water movement. Fixed docks need more allowance for tide changes.
What about line diameter?
Diameter depends on boat size, hardware, and load. Confirm with a marine rope supplier or safety guide.