Submitted on December 15, 2003 by Chris Ditullio 

Question: Hello, I am in the process of designing my sailboat. I am trying to decide between a raked aft (about 5 to 6 degrees) and a straight mast. What are the advantages and disadvantages of each ?  The boat will be a 50' cutter built for offshore sailing. Also, can a boom furling work with a raked aft mast given that the luff and foot of the sail are not at a right angle ?

Thank you.
Chris Ditullio

Answer: Hi Chris, mast rake has a direct effect on the position of the center of effort of the sailplan.  Rake is added or removed to fine tune the balance of the boat since the center of lateral resistance of the foils and hull are fixed.   Mast Rake and Mast Bend should be considered separately. Rake is determined by drawing a straight line from the top of the mast to the mast at deck level and then measuring the angle of that line from horizontal. Mast bend is usually defined as the amount of deflection of the spar forward of the straight line between the top of the mast and the boom attachment point.  Cruising boats rake generally ranges between 1 and 3 degrees of aft rake.  5-6 degrees of rake is pretty unusual.  Most furling boom manufacturers dictate a tack angle (the angle formed by the mast and boom) of 87 or 88 degrees.  If your boat has 6 degrees of rake and an 88 degree tack angle, the boom will be lower at the cockpit end (where your head is typically located) than at the mast end.

Regards,
Dan Neri

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