Continuum robots have been gaining popularity in recent years for their umpteen advantages. Soft robots are a class of continuum robots which are made of squishy materials which have the added benefit of being innocuous to humans. Soft robotic grippers are one of the major application of soft robots as they have the ability to conform and adapt their structure to the object to be grasped. This work presents a bio-inspired technique to increase contact area while grasping and handling long slender objects by helically twisting around them. An embodiment of such a spiral gripper utilizes unique configurations of pneumatically actuated Fiber Reinforced Elastomeric Enclosures which has a range of motions like extension, rotation, contraction. This work presents a detailed analysis technique using Cosserat beam theory to estimate the normal contact force exerted by the spiral gripper on cylindrical objects.