Share 'Alternative Beam Building'

Hallo, im a unknown Beginner. I can buy two unfinishd hull here in the Philippines from a local boatbuilder. I start to make plans to finish the cat. but i have to add and to build the Beam. i saw some pick´s in this forum of building some alternativ Beam. i dont have the plan of the Tiki beam. so i need a alternativ for that. here i have my drawings for the 3th where the mast should be and the 4…