Alan Boswell B.Sc., M.R.I.N.A., C.Eng.

Alan Boswell trained as a naval architect and began his career as a boatbuilder, before working as assistant designer to Angus Primrose in the seventies, when he also met Blondie Hasler and Jock McLeod. He designed the Sunbird 32 during this period as his ideal cruising boat, and after meeting Robin Blain they agreed to form Sunbird Yachts to build and market it. The first boat, Gung Ho, was built at Burne's shipyard in Bosham, UK, and later appeared at the Southampton Boat Show (Gung Ho is currently owned by Rodney Whitworth). During this period Alan and Robin founded the Junk Rig Association to promote the rig more widely, and Alan served as chairman of the association until 1985, and again in 2011-12. During the recession of 1980-81, and exacerbated by the imposition of high levels of VAT in previous years, orders for the Sunbird dried up and boat production was closed down. Sunbird Marine Services continue to offer junk rigs, designed by Alan and with Robin Blain handling the supply and marketing.

Alan's main interest in developing the junk rig during at this time was to get some camber into the sails, in order to improve the upwind performance of the rig. Test rigs were fitted to laser dinghies as comparative trial platforms. They quickly moved on from timber to alloy battens (which were less prone to breakage and lighter and required less maintenance) and then on to GRP tubular battens, and they were able to 'tune' the battens to give the required amount of camber in good sailing conditions, specifying different tube sizes for each batten in each sail. This proved a very simple and robust way of getting camber into the sails proportional to the wind strength in which they would be used, which was found to improve their performance to windward.

Another significant change from the Hasler-McLeod model was to vary the panel height up the sail, with larger panels at the bottom, and panel height steadily decreasing up the sail. This was done because the Hasler-Mcleod rigs were found to be prone to excessive twist. Changing the panel sizes meant the effective pull of the sheets was redirected toward the top of the sail, and this significantly reduced the amount of twist experienced. The sail plans were also modified to incorporate more steeply inclined battens, in response to experiments of Bunny Smith on. However, in time it appeared any benefit from batten angle was minor compared to the effect of camber, and some problems appeared with steeply inclined battens not stacking well as the sail was reefed, so the idea was shelved.

Instead, Alan began to focus on jointed battens which would develop built-in camber in light airs, but would then lock up and not increase the camber as the wind strength increased. Together with a number of interested clients various joints were developed and tested, and these became well established as an option for getting camber into a junk sail. However they do introduce a degree of complication, and proved been rather less popular than GRP battens and the more recent option of building camber into the sail panels.

Over the years Alan has completed over 200 junk rig designs for a small but steady stream of customers for conversions. He also invented the Sunbird SwingWing, a wingsail version of the junk rig, with an elliptical planform and a pivoting aft panel to reverse the camber on each tack. This was fitted to a few boats, but was generally regarded as being a little too complicated to build for most people. It was also quite difficult to use, as it did not give many clues as to when it was properly set.