Mast Section Stiffness
Tests were undertaken to measure the bending characteristics and weights of various mast sections. The bending tests were done on spans of just under a metre using calibrated weights and deflections were measured using a dial gauge reading to .01mm. All tests were repeated 5 times and the averages are the figures shown in the Table. The standard deviation for the tests was under 2%, but it must be expected that some variation will occur between masts of the same type due to material and extrusion variations.
EI is a common way of describing a beam or column stiffness, the larger this number the stiffer the mast. To put it in a more easily understood form the next column shows the load in Newtons (9.81 N= the weight of 1 kg) to cause a deflection of 15mm when placed in the middle of a on a 1 metre span.
The first two tests were on masts from a 2003 and a 2005 rig acquired with a second hand boat. Their provenance is not known. The reason for the popularity of the anodised French sections is evident: they are close to 20% lighter.
The carbon fibre sections cannot be used for IOMs but present an interesting contrast.
Colin Thorne March 2008, revised to add Anodised section 2013
Rigs & Sails