Sentence:  After the frames and transom are set up on the jig and temporarily <WSD>braced</WSD> , a piece of three-inch-wide mahogany ( only widths will be given since the 13 16 - inch thickness is used throughout ) is butted between frames one and two below the line of the keelson . 
Meaning of the word marked with <WSD> tags:  support by bracing