Old System

Originally our topmasts were welded by hand, using a traditional welding rod. The amount of material put into the weld, and therefore left inside the mast as a filet, was totally dependent on the operator and was therefore subject to variation. The operator had to stop and start the weld several times during each taper, increasing the amount of material at the discontinuity, and increasing the heat put into the weld at the point. This introduced another variable both in stiffness characteristics and durability. The weld was fairly untidy as a result of these processes so that the outside surface had to be hand finished by grinding. Due to the uneven nature of the weld and tube, inevitably more material was removed from some areas and spars and less from others, resulting in more inconsistency.

New System

Several years ago we developed a system using automated welding system, but using keyhole shaped extrusion as welding material rather than a welding rod. The extrusion is slid into the gap, and the welding machine passes down the tube in one pass, melting the extrusion and leaving a uniform filet down the outside of the mast. This system is unique to Selden and guarantees that precisely the same amount of material s left in every topmast. The weld is do neat that the system eliminates any need to hand grind the filet, eliminating inconsistencies. The material left on the weld is directly equivalent to the average size and therefore stiffness of the filet left inside the tube with the old method.

Before Selden Masts Limited introduced the new system, samples of every section were bend tested, comparing samples from the same batch of extrusion tapered using the old and new system. No significant difference in bend characteristic was found. Any variations were found to be due to a natural variation in tube thickness as the die wears in time and is eventually replaced, not a difference in characteristic of topmast only. This has always been a characteristic of aluminium extruded spars of any design.

Selden Masts introduced the new welding system on all dinghy spars 2 years ago and had no adverse feedback whatsoever.

New Finishing System

A more recent improvement in quality and production efficiency has been made with the finishing of masts. The much-improved finish is due to the design and investment in the purchase of our new bead-peening machine. Bead peening is a process used in the turbine blade industry to improve finish, and increase fatigue resistant properties. We now no longer need to abrade or etch the surface of the mast to eliminate surface imperfections, again giving a better looking and more consistently performing product. For sailors the side benefit of this system is that their masts will last longer due to the improved fatigue life.