CREATE TABLE table_73987 ("Name" TEXT, "Park" TEXT, "Length  ( ft ) " FLOAT, "Height  ( ft ) " FLOAT, "Speed  ( mph ) " TEXT, "Opened" TEXT, "Status" TEXT)

How long is the rollar coaster on Kemah Boardwalk
SELECT "Length (ft)" FROM table_73987 WHERE "Park" = 'Kemah Boardwalk'
SELECT "Length (ft)" FROM "table_73987" WHERE "Park" = 'Kemah Boardwalk'