Caravel ‘Vera Cruz’ Spars
A caravel (Portuguese: ‘caravela’) is a small, highly manoeuvrable sailing ship developed in the 15th century by the Portuguese to explore along the West African coast and into the Atlantic Ocean. The lateen sails gave it speed and the capacity for sailing into the wind (beating). Caravels were used by the Portuguese for the oceanic exploration voyages during the 15th and 16th centuries in the Age of Discovery. Prince Henry the Navigator, Christopher Columbus, Bartolomeu Dias and Vasco de Gama all used caravels.
The replica Portuguese Caravel ‘Vera Cruz’ is owned by the charitable trust ‘APORVELA’ in Lisbon, which aims introduce school children and adults to sailing and the rich Portuguese maritime history. However, her two original 27m eucalyptus lateen yard spars were both too heavy for young people to haul up the mast and also had a extremely limited life due to rot (see photo below).
Hence, my colleague Dr. Nuno Fonseca and myself (with valuable advice from Paul Miller) designed new custom carbon fibre spars, at no cost. This included laminate material property and scale replica testing.
The main design problems were that loading and geometry were both non-standard and variable (the yard is in bending around the mast, and is free to move in all three directions), and that there was no available data for lateen sail rig loads.
Hence, the design process ensured that the carbon beams were as stiff as the original eucalyptus spars (tweaking the tip geometry to give a little more twist off in the gusts), whilst ensuring no significant loss in strength. Checks were also made against data from similar sails, and scale model tests provided an extra verification.
Mário Figueiredo fabricated the mandrel moulds and spars following our custom designed ‘robust’ production processes, which also allowed the same moulds to be used for both main and mizzen yards. The spars were vacuum laminated in two halves which were then bonded together and post-cured in a heated tent.
The crew of the Vera Cruz decided on an Atlantic crossing to Madeira as a first ‘sea trial’ which was a little worrying at the time (!), but was a great success; in the words of the skipper, ‘we sailed over 800 nautical miles with fair winds (around 35 knots!) and the spars always performed well’.
The feedback from consequent regular voyages in and around Lisbon is that the spars are both extremely light and so easy to haul up and down, and that they perform excellently under sail.