RIGBOOK

A Mast is a steel framework with square or rectangular cross-section comprised of multiple sections assembled together.
Mast are normally used on land rigs; they are rarely used on offshore rigs.
Most masts have one side open (window side), while others have both the front and rear side open
(full view).
Generally masts are assembled on the ground in horizontal position and are raised using the drawworks. Some masts use telescopic sections and are assembled in vertical (boot strap).
- API Definition
3.16 mast: A structural tower comprised of one or more sections assembled in a horizontal position near the ground and then raised to the operating position.
If the unit contains two or more sections, it may be telescoped or unfolded during the erection procedure.

Mast Types
There are 2 different types of masts for land drilling and service rigs:
- STATIONARY BASE
- WITH GUY LINES