Marine Swinging Circle Calculator
Calculate a geometric radius from a straight taut rode, vertical depth and vessel length.
A QUICK WALKTHROUGH
How to use this tool
- Enter rode length, vertical depth and LOA in metres.
- Calculate the result.
- Copy the report or download it as TXT.
Formula and units
Horizontal reach = sqrt(rode² − depth²). Radius = horizontal reach + LOA. Rode must be greater than depth; depth and LOA must be nonnegative. A scaled equivalent avoids squaring the input lengths.
Scope
Only a straight, taut rode with a fixed anchor is modelled. The radius is a geometric envelope, not a prediction of actual vessel position, collision risk or safe clearance. Catenary, dragging, vessel motion, wind and current are excluded. No anchoring recommendation is supplied.
Local processing
Your entries stay in your browser. Copy and TXT export include the inputs, formula and scope.
GOOD TO KNOW
Common questions
How should I use the result?
Use it as an arithmetic estimate based on your supplied inputs.