This group of surveys include those drilled by percussion, rotary, or conventional coupling-rod techniques and where there is no unobstructed passage within the drill rod or pipe.
The TROPARI can be lowered into steep down holes (> 40° from horizontal) by cable if a winch is available. The survey train shown in
Fig. 1 is an example of a cable lowered application. If drill rods are used to insert the instrument into the hole, then the inclination of the hole, whether up or down, is immaterial. The survey train in
Fig. 1 is converted to rod insertion simply by replacing the cable swivel with a connector that joins the aluminum rods to the drill rods or drill pipe. The aluminum rods separate the instrument in the "container" from the magnetic effects of the lowering devices.
The surveys of steep short holes can be done by rope lowering or, for holes at any inclination, by light aluminum rods hand inserted. Aluminum rods for hand insertion are available in 1.5 m connectable lengths in sizes that weigh as little 7 kg (15 lb.) per 30 m (100 feet).
Hole sizes from 36mm (1.4 inches) to 600mm (24 inches) can be carried out in holes drilled by any technique. The hole size, and if drill rod insertion will be used, the type or description of the drill rod thread is required information to select the components of the survey train.