All that You need to determine which size top to order is choosing the length, height, and width that best accommodates your boat and your needs. Remember that height as well as length determines how much shade your bimini top will provide. Consider the coverage area when the top is opened and also where it falls when it's closed and folded down at the rear of the boat. Make sure that there is enough space in front of and behind the opened top to mount eye straps to secure the tie-down straps.
Using a tape measure, decide which length top provides the desired amount of shade to your boat.
The pivotal mounting point will be approximately at the center point of the top on each side of the boat. Swivel deck mounts included with the top are designed to mount on a variety of flat surfaces. Optional mounts are available on this page.
After determining where the pivotal mount location will be on each side of the boat, measure the distance between these mounting points to determine the width of top you need. This measurement is not the same as the beam width of your boat. The frame has some flex so it can be mounted over the width range indicated in the selection chart. Choose the width that most closely matches your mounting point width measurement.
While inside the boat, measure from the pivotal mounting point on the hull side and measure straight up to determine the desired height. This measurement should be the minimum headroom clearance desired. Note that the height of the top is not the distance from the boat floor or the length of the frame arms. Straps allow 2"-3" of height adjustment.