I checked each entry in the vbo to see that each entry has r=0,g=1.0,b=0.0 and from the spreadsheet I exported things look OK a green vertex each time. For some reason there is a blending when drawing the third arrow. Why might the third arrow have this blending going on?
In this case I had a misunderstanding so far about the usage of drawArrays but it seems that correct usage should be like:
glDrawArrays(GL_LINE_STRIP, int(self.vertices_start/self.bufwidth), self.entitycount)