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DB
Dinghy BaseTODAY'S SETUP

YOUR SAILOR · YOUR KIT · TODAY'S CONDITIONS

Set the boat up for today.

Start with the common tuning physics, then let the sailor, exact sail and spars refine the setup where the evidence supports a real difference.

Wind10 kn
17142128 kn
Building7–10 kn
Equipment details0/4 selected

Mast, boom and sprit are independent. Mix and match them to describe the boat that is actually being sailed.

Selecting a sail automatically chooses its specific guide where we have one. This control lets an expert override that for comparison.

DINGHY BASE STARTING SETUP

Building · 10 kn · flat water

The boat is the interface. Tap a labelled part to see what to do and why.

LIVE TECHNICAL RIG10 kn · 40 kg · flat water
SAILGeneric race sail
Mast · GenericBoom · GenericSprit · Generic
Interactive side-on Optimist technical rigMeasurement-led Optimist side elevation with the mast passing through its thwart, seated in the mast step, a single-line kicker, a simplified true sprit-halyard run and the sail throat at the masthead.Mast rakeLuff tiesSpritVangOuthaulBoom tiesLuff / cunninghamSTERNBOW
Class-rule datums for mast/boom · corrected thwart and mast step · simplified real rigging paths.Dynamic cloth shape remains illustrative, not CFD

Luff ties

Useful consensus
Bring the sail closer and more parallel to the mast: roughly 2–3 mm is a sensible starting range.

Across the strongest guides, tie spacing is used to let the luff follow mast bend and to control depth. Exact patterns vary by sail, so this is a starting envelope rather than a copied table.

Sprit

Strong consensus
Increase just enough to reduce the wrinkle while preserving an active leech.

The shared objective is leech support when powered and deliberate leech opening when overpowered. Wrinkle appearance is often a better target than a fixed line length.

Vang

Strong consensus
Light tension: enough to stabilise the leech when the sheet eases.

This is one of the clearest points of agreement: little or none in light air, progressively more as wind increases.

Outhaul

Strong consensus
Eased progressively as the sailor approaches full power.

Depth is useful through the powered range; flat water can tolerate a cleaner/flatter shape, while chop usually benefits from more punch.

Luff / cunningham

Strong consensus
Still relatively soft, but remove excessive slack as pressure builds.

Most guides move from low/slack luff tension towards firmer tension as the rig becomes overpowered.

Boom ties

Useful consensus
Allow the foot to work: around 7–8 mm is a common racing starting point, then use the outhaul for most lower-sail depth control.

Around 8 mm appears repeatedly as a racing baseline; strong-wind setups commonly bring the foot a little closer. Treat this as secondary to the outhaul.

Mast rake

Equipment-specific
Do not use a universal wind-to-rake formula. Start from the sail/boat base rake and tune for helm balance. Manufacturer guides genuinely disagree on the direction and amount of rake change with wind.

North, Doyle and Landenberger publish materially different wind/rake progressions. Averaging them would create false precision.

Sailor-weight adjustment

Useful consensus
Mid-weight sailor: use the wind band as the main starting point, then tune to feel and sea state.

Weight changes how early the sailor becomes overpowered; it should shift how aggressively the common settings are applied, not create a separate tuning system.

HOW THE MODEL THINKS

Common physics first. Exceptions only when the evidence earns them.

1Wind sets the basic power/depower state.
2Weight changes how early the sailor becomes overpowered.
3Sea state changes how much depth and acceleration are useful.
4Mast stiffness changes how the luff follows bend.
5Exact sail guidance overlays the common model where manufacturers genuinely differ.

EVIDENCE BASE

Manufacturer guides currently feeding the model

North Sails V-SeriesCurrent V-Series tuning tableJ SailsClassic, 2.0 and B3 tuning guideOneSailsOptimist tuning tableCD Sails DRSDRS semi-radial tuning guide and rig guidance3FL SailDesignOptimist tuning guideDoyle SailsOptimist technical tuning guideLandenberger OneDesignOptimist tuning guide

Dinghy Base does not average conflicting numbers into false precision. Mast rake is the clearest example: different manufacturers publish different progressions, so the common model explains the principle and preserves the sail-specific figure as an overlay.