How to Measure your OK Mast Bend


All North OK sails are tailored to your individual mast. Follow the steps below to measure your mast bend. If you have any questions about this measurement process please contact our OK Class Specialist Paul Hobson.

For your convenience please print this page and fill out the tables below with the measurements of your mast.

Measurement Instructions

Step 1: Support the mast with the tip at a height which will allow the tip of the mast not to hit the ground when the weight is placed on it. Fix in place at the butt to allow it to rest on the collar as it holds by the mast step and deck of the boat. Mark the point A. See picture below.

Step 2: Place the weight (10kg sideways / fore & aft) on the tip of the mast at the measurement band. Mark the point B for sideways and fore & aft.

Step 3: Take a taught string from the top of the bottom measurement band (D) to the bottom of the top one (C).

Step 4: Measure the distance in millimeters between the string and the mast (sideways and fore & aft) in every 1/4 of the distance CD.

OK Mast Bend Measurement

Mast Type  
Phone number

 1/4  1/2  3/4
Fore & Aft      

 Fore & Aft  Sideways
Tip Bend (AB)    

Please take measurements in mm.