By Matt Claiborne
A ketch is a two-masted sailboat. The rear mast, called the mizzen mast, is shorter than the forward main mast. The mizzen mast is mounted forward of the rudder post.
A yawl is similar to a ketch, but the rear mizzen mast is moved farther aft, behind the rudder post. This makes the mizzen on a yawl seem like an afterthought, almost like it’s attached to the railing.
If a two mast boat has masts of equal height or the forward mast is the shorter of the two, it is a schooner. They can have as many masts as the design called for.
Easy to balance steering forces
More sail plan options for heavy winds
Lower sheet loads mean smaller and less expensive
Lighter loads on smaller sails for easier handling
Shorter overall mast height for bridge clearance
Mizzen can be used as a riding sail at anchor
A brig is a double mast sailboat with both masts square rigged. In addition, it has fore-and-aft staysails and jibs and a mizzen sail on the aft mast–which is usually gaff-rigged.
A brigantine is a ship with two masts, with the foremast square-rigged and the aft mainmast fore-and-aft rigged.