Spinnaker and Gear Specifications
Not nearly enough info. Mast height is only one of many questions to be answered. The boats "J" dimension is another. Also, you don't say what kind of spinnaker. Are you looking for a symmetrical with spinnaker pole or an asymmetrical cruising chute or racing Akite. The type of sailing you do is also useful to determine the weight of the cloth. For light air sailing a 1/2 oz cloth is best, for moderate breezes, 12 to 18 kts 3/4 oz cloth would be better. Heavy air, 20+ kts would require 1 1/2 oz cloth.