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. Her two original 27m lateen yard spars were of eucalyptus and were both too heavy for young people to haul up easily and also had a limited life due to rot.
The production process, laminate schedule and dimensioning of new carbon fibre spars, including laminate material property and scale replica testing (‘always test the theory’) were carried out, for free (and for fun) with my colleague Dr. Nuno Fonseca.
The main design problems encountered 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, since the existing yards performed well but were just too heavy and susceptible to rot, the simple and practical approach was taken of ensuring that the stiffness of the beams was as high as that of the original eucalyptus spars (tweaking the tip geometry to give a little more twist off in the gusts), whilst ensuring that the strength was also close to that of the original spars. Approximate checks were also made with similar sail data to ensure the yards were strong enough.
Mário Figueiredo fabricated the moulds and spars in a disused shipyard and so relatively ‘robust’ production processes were designed. The moulds also had to be used for both main and mizzen yards, adding further design and production constraints. The owners specified a fully carbon fibre construction. 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 a 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 from Lisbon is that the spars are both extremely light, making them easy to haul up and down, and that they perform excellently.