SailEdge™ by SailrScience makes CE visible — computed for every sail, every wind condition, every configuration. In three dimensions. In real time.
Explore Your Edge See the Edge Map →Force Balance Diagram
Most references to Center of Effort treat it as a point on a sail plan drawing. SailrScience computes it as a three-dimensional position that moves with every change in wind, sail selection, reef state, and heel angle.
How far forward or aft CE sits along the deck. This is the axis that drives weather helm. Move CE forward and the boat wants to bear away. Move it aft and you get helm pressure.
How high CE sits above the waterline. Higher CE means more heeling moment for the same force. Reefing lowers CE. A staysail keeps CE low. This is the axis that governs comfort and control.
How far CE moves to leeward under heel. As the boat heels, CE shifts laterally — increasing the moment arm and changing the balance. This is the axis most sailors never think about.
Most models place CE from generic rig ratios. SailrScience starts from centroid geometry — the measured planform of each sail — and models the center of effort from that geometry, the active aero profile, trim state, and wind condition. Tack, head, clew, plus roach profile when available. CE is a computed force-application point, not a direct measurement of the flying sail.
A high-roach main puts CE higher and further aft. A deep-LP genoa moves it forward. The geometry is traced back to sailmaker cut-sheet measurements, and the model computes the force point from it. When you change sails in the model, CE moves for the right reasons.
CE is one piece of the force balance. See how drive, side force, heel, and depower all connect. The Physics →
SailrScience computes CE individually for each sail — main, headsail, code sail — and then calculates the force-weighted combined CEeff that represents where the total aerodynamic force acts on your boat. The combined CE marker points straight down to the deck, showing you exactly where the resultant force meets the hull. This is the number that matters for balance.
Sitella (Cape 31) broad reaching at TWA 134°, 12 kt — Main (Mn-25), Headsail (J1-25), Asymmetric (A1.5-25)
More area moves CE forward and higher. Your digital twin shows exactly where CE lands with the new sail at every wind angle — before you spend the money.
CE is too far aft, too high, or both. See CE position at 16 kt with your current plan — and what happens when you switch to the jib, add a reef, or both.
Reefing reduces area but lowers CE height, cutting heel moment. At some wind speed, reduced heel gives back more than the lost area costs. CE shows you where that crossover is.
For sailmakers iterating on a design, CE tracks how planform changes shift the force application point. Different roach, different LP, different CE trajectory — visible across every regime.
Center of Effort above the water. Center of Lateral Resistance below it. The relationship between them determines whether your boat has weather helm, lee helm, or neutral balance. SailrScience computes both — and shows you how every sail change, reef, or furl shifts that balance.
When the mainsail blankets the headsail at deep angles, occlusion reduces headsail lift and shifts the combined CE. The balance you see reflects sail interaction, not just individual sail positions.
This is what experienced sailors feel. When they say "the boat feels heavy" or "she's balanced beautifully," they're describing the CE—CLR relationship. SailrScience makes that feel visible — the offset in meters, the heel it drives, and how it changes with every puff and header. What took decades to develop as instinct, your crew can now see on screen before leaving the dock.
The force-weighted center of all aerodynamic forces. Moves forward with bigger headsails, moves up with more sail area, drops with reefs. The variable you control through sail selection and trim.
The center of all hydrodynamic resistance — keel, rudder, hull. Relatively fixed by the boat’s design but shifts dynamically with boat speed and heel angle. The anchor point that CE pushes against.
CLR (Center of Lateral Resistance) — the underwater pivot point where hydrodynamic side forces act on the hull and keel.
The horizontal distance between CE and CLR — the offset that creates helm. CE ahead of CLR means lee helm. CE aft of CLR means weather helm. In sign convention terms, positive Lead is forward (lee helm), negative is aft (weather helm). A few tenths of a meter is the difference between a balanced boat and one that fights you.
The vertical distance from CE down to CLR — the lever that turns side force into heeling moment. Higher CE, longer arm, more heel. Reef the main and the arm shortens before the force drops. That’s why a first reef often feels like free speed.
CE is where the wind’s force acts. CLR is where the water pushes back. The third force decides how much of that push your boat can stand up to: righting moment — the stability envelope built from hull form, ballast, and crew. It has its own page in SailEdge — Boat Tuning — but it belongs in this picture, because balance is never just CE and CLR.
Every number SailEdge reports is an equilibrium of these three forces: drive against drag, heeling moment against righting moment, sail force against keel and rudder. Change one — a reef, a heavier crew, a different headsail — and the other two respond, and the equilibrium is re-solved. That solve runs across the 850,000+ physics evaluations behind your Edge Map. The balance you read on this page is computed force physics, not a rule of thumb. See where the forces balance →
A rudder held at angle to fight the helm is drag — all day, every leg. When CE sits too far aft or too high for the conditions, helm load rises, rudder angle grows, and the groove narrows: the band of headings where the boat is fast gets smaller, so every small steering error costs more. Bring CE forward or down — a different headsail, a reef, a flatter trim — and the same hull sails a wider groove with less rudder drag.
Weather helm building, rudder angle climbing, drag rising with it. A narrow groove that demands constant attention from the helm.
Helm near neutral, the rudder steering instead of correcting, a groove wide enough to sail fast for hours. The boat is easier to sail — and faster because of it.
These are not qualitative judgments. Lead in meters. Heel in degrees. Your digital twin reports them for every sail plan you own, at every point of sail — CE meets CLR, solved before you leave the dock. Balance is speed you keep or give away. See the racer’s path →
The three-force system on this page — per-sail force and centroid computation resolved into a combined center of effort, balanced against CLR and righting moment — defines what your boat can do at every wind speed and angle. That physics foundation is what the roadmap builds on.
Where this physics sits alongside the ORC framework: ORC & SailrScience →