Visiting the pontoon (1): the daggerboards

Daggerboards and centreboards are vital to move the centre of lateral resistance to offset changes to the sailplan (the surface that  provides lateral resistance to displacement of the yacht) when the keel is raised, or 'canted'.

We have all seen spectacular photos where the keel almost comes out of the water and it's obvious that in a situation like this, the boat needs a centreboard so that it doesn't 'skid' sideways.

The earliest centreboards were straight and symmetrical: the step towards asymmetric centreboards was soon made, with these working close to the vertical when the boat heels (see diagram), maximising their surface area to fight the sideways drift. Recently, the VPLP and Guillame Verdier designers have come up with curved centreboards which take advantage of the foil effect produced by their profile and which generate a force which pushes the hull upwards, out of the water, in the same way a wing keeps an aeroplane up in the air.

The three types of centreboard in the Barcelona World Race

The curved daggerboards of Virbac-Paprec 3.	As the keel is canted the righting moment increases but the ability to counteract leeway is correspondingly reduced.
Foncia's daggerboards: inclined inwards	The daggerboards of GAES Centros Auditivos: straight and slanting outwards