SAILING SPEED
CALCULATOR

Sailing + Oars Travel Calculator

Enter vessel parameters once, then save segments to build a route. Each saved segment computes travel speed (VMG along the course), rowing limits per 24h day, and time to cover that segment under constant daily wind.

Vessel

Waterline length (LWL), ft

Hull speed uses 1.34 × sqrt(LWL).

Rig

Affects no-go angle and reach/downwind efficiency.

Beam, ft

Simplified stability vs wetted-surface tradeoff.

Cargo/load, metric tons

Affects sailing efficiency and rowing via displacement.

Wind steadiness

Small modifier to effective driving wind under sail.

Windage profile (for rowing into headwind)

Only affects rowing (headwind drag approximation).

Oars (power-based)

Crew available for oars

We ignore crew constraints for sails/steering.

Oars (count)

Assume 1 crew member per oar.

Rowing assumptions (travel mode defaults)

Sustainable power per rower (W)

Travel mode default: 100 W per rower.

Rowing hours per crew member per day

Total daily rower-hours = crew × this value.

Oar/propulsive efficiency

Higher = more of rower power becomes useful thrust.

Coordination factor

Timing losses, fatigue management, etc.

Rowing calibration constant (K)

Tuning knob: higher makes rowing faster.

Rowing speed cap (fraction of hull speed)

Rowing won’t exceed this fraction of hull speed.

Interpretation: “Course” is the straight-line direction you want to make good. If it points into the rig’s no-go zone, the sail model assumes tacking and returns VMG along the course.

Segment builder

Set up a segment here, then click “Save segment to route”. Saved segments appear below and remain editable.

Saved route segments

Disclaimer: This tool is for use with tabletop roleplaying games. Do not use for real world navigation. Vibe coded with the help of Chat GPT 5.2.