The J-5 has been designed with a square top head to boost area and aid the twist profile allowing the head to open smoothly as the wind increases. It is built with radial construction in the head and clew and cross cut panels through the middle. This produces a very smooth and easy to use sail which copes better with the high loads in the corners than a traditional cross cut sail, allowing the sail to maintain it's racing shape for longer. It is manufactured from DP 185 SQ HTP+.