Sails

Sail Inventory Considerations

I highly recommend Bill Shcaefer’s excellent youtube series on the complete restoration of a Bill Lapworth designed Cal 40. One of the most interesting videos of the series is the one where he talks with Kame Richards from Pineapple Sails about new sails for the boat. It is full of valuable insights for any one considering upgrading the sail inventory of an older boat.

Kame begins by looking at Bill Lapworth original hand drawn plan from 1963 which is typical of that era – and includes a list of recommended sails. The sail plan with its overlapping head sails is similar to that of the Alpa 11.50, with the luff of smaller sails steadily marching down the forestay. Kame contrasts this with the modern approach – in today’s sails the head stays right at the top of the forestay, and it is the angle of the leech that changes as the head sail gets smaller. Modern head sails thus have a much more blade like shape – which is more desirable from an aerodynamic point of view. Kame explains that this evolution has been made possible by modern materials – in the past sailcloth could not have endured loads at such shallow angles…

In the video, Kame also explains some of the advantages of modern asymmetric down wind sails. For offshore racing he recommends adding a jib top and a light running asymmetric spinnaker to the sail inventory. A jib top is a high-clewed head sail used for tight beam reaching. An asymmetric spinnaker transfers sail area from the leach end of the sail to the luff end of the sail, effectively moving the centre of power forward. This has the advantage of making the boat more controllable, by reducing the amount of weather helm. In a racing context this means that one can handle more power without being overwhelmed compared to a traditional spinnaker. An asymmetric sail will also help in keeping the bow down, which maximises waterline length and thus speed and also helps control.

Kame and Bill also discuss the importance of being able to control backstay tension. As wind increases and the headstay sags, the head sails gets fuller and fuller, generating more power, the boat heels over more, develops more weather helm, and does not sail upwind as well. To counteract this phenomenon a good backstay adjuster system is essential. However on older boats there can be such a thing as excessive backstay tension – after a certain tightening tension the backstay will just bend the hull, reducing waterline length and making the boat slower not faster…