English to Spanish Science Archaeology

Hi fellows. I am currently translating an article on Underwater Archaeology. I have not been able to get an equivalent in Spanish for the word offset. Could you wood me with this, please. Below there is the text where it appears a couple of times and one of Webster's Dictionary definitions for the said term matching the situation involved:

Webster's: Offset: Surveying a short distance measured at right angles from the main line to help in computing the area of an irregular plot of ground


Offsets
Offsets are measurements that position features relative
to a tape baseline fixed between two control points. An
offset measurement positions a feature using a single
measured distance at right-angles to the baseline from a
known point, and is simple and effective over small
areas. Two divers are needed for these methods, one at each
end of the tape-measure. Like radial surveys, the positions
are usually only given in two dimensions although spotdepths
can also be recorded. Offsets are most frequently
used for assessment surveys, for recording detail or in
confined areas such as rock gullies.
The first step is to set out a tape-measure baseline
between two control points, which runs through the centre
of the area to be recorded, and with a clear line of sight
between the two points. Distances are measured from
this baseline, horizontally or vertically, to features on the
site using a tape-measure or measuring rod. Vertical
offsets are often used for measuring profiles of ships’
timbers (figure 14.4 and plate 14.1). To position using
an offset, a measurement is made from the feature to the
point where the offset measurement meets the baseline
at a right-angle (figure 14.5(1)). The right-angle point
can be found by swinging the ‘offset’ tape-measure and
finding where the distance to the baseline is the shortest
(figure 14.5(2)). In poor visibility it may be useful to have
a second diver swim up and down the ‘offset’ tape to ensure
that it is not snagged.