The invention relates to a profile sail boom for a boat having a batten mainsail, which is configured to be flexible in the horizontal direction and has a vertical spar with cords laminated in at the uppermost and lowermost points in the center of the cross-section, transverse webs separated by wedge-shaped spacer joints extending from said spar on the lowermost site in the horizontal direction, wherein guiding tubes for cords are present on the outer edges of said webs.