All dimensions for mast plates are measurements of the flat surface of plate making direct contact with the deck.
Plate Size-L x W x H:
5-1/2" x 3-3/4" x 1-3/8"5-3/4" x 4-3/4" x 1-1/2"7" x 4" x 1-3/8"9-1/2" x 6-1/8" x 1"10-3/8" x 7-3/8" x 1-1/8"7-1/2" x 1-1/8"