Introduction
The Yachting World Dayboat (YWDB) offers a wonderfully adaptable platform, with small but meaningful variations between wooden hulls and more recent GRP builds. Despite these differences, the principles behind fast, balanced sailing remain the same. At Sanders Sails we have worked closely with many of the class’s leading sailors; including the current National Champion to refine a tuning approach that reliably unlocks the best performance from our sails on any YWDB. This guide focuses on getting your rig geometry set correctly for a Sanders sail plan, including mast position, rake, forestay tension, spreader configuration and jib selection.
Mast Position at Deck Level
Your mast position at deck level has a significant influence on helm balance, rudder angle, and overall stability. With a fixed mast rake, the mast heel effectively allows you to move the entire sail plan forward or aft within the boat:
- Moving the mast forward shifts the sail plan’s centre of effort forward, reducing helm and lightening the feel.
- Moving the mast aft shifts the centre of effort aft, increasing helm and creating a more ‘locked-in’ upwind mode.
Although each boat will have small dimensional differences, reviewing multiple boats shows that a measurement of 1.30 m from the stem to the front face of the mast provides an excellent starting base.
Wind strength and sea state may require small refinements:
- Flat water / light airs: Move the mast slightly aft to introduce more helm, helping achieve a higher pointing mode.
- Chop / strong breeze: Shift the mast slightly forward to reduce helm load and maintain speed in a lower, freer mode.
A sensible adjustment range is ± 3–4 cm from the 1.30 m baseline.
Recommended Mast Position Settings:
| Conditions | Stem to Front of Mast |
| Flat Water / Light Wind | 1.33m |
| Base Setting | 1.30m |
| Chop / Strong Breeze | 1.27m |
Mast Rake
There are several ways to record mast rake, but the most reliable method is to hoist a tape measure on the main halyard to the top band, and first confirm a consistent internal reference:
- When the halyard is tensioned down to the top edge of the lower black band, it should read 5563mm.
- From here, measure to the top of the transom.
The most effective rake range for the YWDB is typically 6730–6780 mm. Within this:
- More upright mast (higher number): Increases available power, useful in flatter water and light-to-moderate winds.
- More rake (lower number): Opens the leech, reduces power, and helps balance the helm in stronger breeze.
Once you reach your ‘max power’ upright setting, you can progressively increase rake as wind strength builds to allow the mainsail to twist and depower more effectively.
Spreaders, Pre-Bend and Mast Bend
Spreaders are a vital tool for controlling mast bend, and therefore the mainsail’s depth and unlocking depowering potential.
- Shorter spreaders allow more mast bend, helping depower efficiently.
- Longer spreaders restrict bend and maintain a fuller mainsail.
After significant on-water development work with the fleet, we recommend:
- Spreader length: 460 mm
- Spreader deflection (sweep): 212 mm from the back of the mast
At Sanders, we design luff curves for a controlled pre-bend of 5–10 mm.
Measuring Pre-Bend
- Hoist the jib and tension the rig to your chosen rake.
- Pull the main halyard tight to the gooseneck to create a straight reference.
- Measure the maximum distance between the halyard and the back of the mast at spreader height.
For optimum performance, we prefer to see no more than 12 mm of pre-bend.
Why This Matters
The mainsail luff curve is built to match a specific mast bend profile:
- Too much pre-bend: Flattens the sail prematurely, reducing drive.
- Too little pre-bend: Leaves the sail too full with the draft too far aft, increasing helm and drag.
Matching mast bend to the designed luff curve gives predictable trim, balanced helm, and consistent acceleration across wind ranges.
Jib Design and Luff Length Options
At Sanders we offer three jib designs, each with a different luff length. This allows precise control over clew height, sheeting angle and slot shape.
How Luff Length Influences Performance:
- Longer luff: Clew must rise to remain within class leech length limits; results in a more aft sheeting position.
- Shorter luff: Allows a lower clew and improved sheeting angle, bringing the lead position closer and forward.
Our most popular option is the medium luff (3.81 m), which provides an excellent balance of sail area, clew height, and sheeting geometry for a wide range of mast rake settings.
The 2026 Jib – Updated Foot Engineering
For 2026 we have introduced:
- Refined foot shaping
- Vertical darts to stabilise the lower panels
- Reduced tendency to ‘flutter’ when close-hauled
- Improved shape retention when reaching
These refinements follow extensive collaboration with the top Dayboat sailors, ensuring that the new jib delivers stable, efficient performance across all modes.