Best materials for welding companies.
This is a mast that is made out of Aluminium. Welding companies who offer welding services to marine customers often use Aluminium for manufacturing top parts of the boats in order to keep center gravity low. As lower it is as more stable boat will be so welding companies use lightest possible materials for the mast as it it highest point of the vessel.
If you would like to use this image for your own purposes, you more then welcome to do so, just make a reference that image is a courtesy of http://weld-delux.co.uk/