This method is used for a wide range of applications and can be used for either cased or uncased holes that are larger than 35.6mm (1.4”). Cable lowering is commonly used for holes inclined greater than 45°.
This range can be increased to holes inclined greater than 35°
with the addition of roller sections.
Centralizers are used
improve parallelism between the axes of the instrument and the borehole.
They are not required for holes which are close to the diameter of the
instrument. Aluminum rods between the centralizers can be used to increase
surveying accuracy. Sinker rods can also be used to increase the survey
trains weight which results in faster lowering speeds in water filled holes.
Other arrangements of the survey train are possible to reduce weight which
can be helpful in many applications such as lowering the survey
train by hand in short holes.
Cable lowered surveying is typically used when the drill is no longer on the site
or for other applications such as conventional drilling when a fast surveying method in
to provide when requesting a quotation:
available, please includes details about your surveying application so
we can provide a detailed quotation and/or additional information.
Common details to include are:
is the diameter of the hole?
is the direction (upward, downward, horizontal, etc) of the hole?
is the length of the hole?
the hole water filled?
the hole cased?
the hole is cased, what material (steel, plastic, etc) is it cased
the hole is cased, what is the inside diameter of the casing?
SDP applications with magnetic azimuth measurements:
Please note that the Tropari SDP is a magnetic
azimuth instrument. It does not measure azimuth direction while inside
holes that are cased in steel or while inside steel drill rods. Azimuth
measurements can be performed in uncased holes and holes that are cased in
non-magnetic materials such as plastic. The survey train for this
surveying method includes non-magnetic rods which extend the instrument
beyond the magnetic influence of the cable and cable swivel.